[Federal Register Volume 69, Number 160 (Thursday, August 19, 2004)]
[Notices]
[Pages 51507-51544]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-18905]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
Announcement of FAA Advisory Circular (AC) 120-27D, Aircraft
Weight and Balance Control
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of availability of AC, and request for comments.
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SUMMARY: This notice announces the availability of and requests
comments on AC 120-27D, which provides guidance on the requirements for
maintaining an aircraft weight and balance control program.
DATES: Submit comments on or before September 17, 2004.
ADDRESSES: Send all maintenance-related comments on AC 120-27D to Mr.
Darcy D. Reed, Aircraft Maintenance Division, Air Carrier Maintenance
Branch (AFS-330), Federal Aviation Administration, 800 Independence
Ave., SW., Washington, DC 20591; facsimile (202) 267-5115; e-mail
[email protected]. Send all operations-related comments on AC 120-
27D to Mr. Dennis Pratte, Air Transportation Division, Air Carrier
Operations Branch (AFS-220), Federal Aviation Administration, 800
Independence Ave., SW., Washington, DC 20591; facsimile (202) 267-5229;
e-mail [email protected].
FOR FURTHER INFORMATION CONTACT: Mr. Darcy D. Reed, AFS-330, at the
address, facsimile, or e-mail listed above, or by telephone at (202)
267-9948; or Mr. Dennis Pratte, AFS-220, at the address, facsimile, or
e-mail listed above, or by telephone at (202) 267-5488.
SUPPLEMENTARY INFORMATION:
Comments Invited
AC 120-27D is available on the FAA's Regulatory Guidance Library
Web site at http://www.airweb.faa.gov/rgl, under the Advisory Circulars
link. Interested persons are invited to comment on the AC by submitting
written data, views, or suggestions, as they may desire. Please
identify AC 120-27D, Aircraft Weight and Balance Control, and submit
comments, either hardcopy or electronic, to the appropriate address
listed above. Comments may be inspected at the above address between 9
a.m. and 4 p.m. weekdays, except Federal holidays.
Issued in Washington, DC, on August 11, 2004.
John M. Allen,
Deputy Director, Flight Standards Service.
BILLING CODE 4910-13-P
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[GRAPHIC] [TIFF OMITTED] TN19AU04.000
BILLING CODE 4910-13-C
Table of Contents
Chapter 1. Introduction
100. What is the purpose of this advisory circular (AC)?
101. How is this AC organized?
[[Page 51509]]
102. What documents does this AC cancel?
103. What should an operator consider while reading this AC?
104. Who should use this AC?
Table 1-1. Aircraft Cabin Size
105. Who can use standard average or segmented weights?
Chapter 2. Aircraft Weights and Loading Schedules
Section 1. Establishing Aircraft Weight
200. How does an operator establish the initial weight of an
aircraft?
201. How does an operator document changes to an aircraft's
weight and balance?
Table 2-1. Incremental Weight Changes that Should Be Recorded in
a Weight and Balance Change Record
202. How does the operator maintain the OEW?
203. How often are aircraft weighed?
Table 2-2. Number of Aircraft to Weigh in a Fleet
204. What procedures should be used to weigh aircraft?
Section 2. Aircraft Loading Schedules
205. What is a loading schedule?
206. How should an operator determine the weight of each fluid
used aboard the aircraft?
Section 3. Constructing a Loading Envelope
207. What should an operator consider when constructing a
loading envelope?
208. What information from the aircraft manufacturer should an
operator use?
209. What should the operator consider when curtailing the
manufacturer's loading envelope?
210. What are some examples of common curtailments to the
manufacturer's loading envelope?
Section 4. Automated Weight and Balance Systems
211. How does an onboard weight and balance system compare to a
conventional weight buildup method?
212. What measures should an operator take to obtain operational
approval for an onboard weight and balance system?
213. What operational considerations should an operator take
into account when using an onboard weight and balance system?
214. May an operator use the information in this AC to develop a
backup system?
215. What operational considerations should an operator take
into account when using a computerized weight and balance system?
Chapter 3. Methods to Determine the Weight of Passengers and Bags
Section 1. Choosing the Appropriate Method
300. What should an operator consider when choosing the
appropriate method?
Section 2. Standard Average Weights
301. What standard average passenger weights should an operator
with an approved carry-on bag program use?
Table 3-1. Standard Average Passenger Weights
302. What standard average weights should an operator use for
carry-on bags and personal items?
303. What standard average weights should an operator use for
checked bags?
304. What standard average weight should an operator of large
cabin aircraft use for bags checked plane-side?
305. What standard average weights should an operator of small
and medium cabin aircraft use, if it has a ``no-carry-on bag
program?''
Table 3-2. Average Passenger Weights for Operators with a No-
Carry-on Bag Program
306. What are the standard average weights for crewmembers?
Table 3-3. Standard Crewmember Weights
307. What weights may be used for company materials and mail?
308. What are the standard average weights for special passenger
groups that do not fit an operator's standard average weight
profile?
Section 3. Average Weights Based on Survey Results
309. What should an operator consider when designing a survey?
310. What sample sizes should an operator use?
Table 3-4. Minimum Sample Sizes
311. When conducting a survey, can an operator collect a smaller
sample size than that published in Table 3-4?
312. What sampling method should an operator use?
313. What should an operator consider when developing a survey
plan and submitting it to the FAA?
314. What general survey procedures should an operator use?
315. What information might an operator gain from conducting a
count survey?
316. When should an operator conduct another survey to
revalidate the data from an earlier survey?
Section 4. Segmented Passenger Weights
317. What should an operator consider when using segmented
weights?
Table 3-5. Segmented Weights for Adult Passengers (in Pounds;
Summer)
318. How are loading envelope curtailment and bag weight
affected by an operator's use of segmented weights?
319. What might be an example of an operator using the segmented
weights in Table 3-5?
Section 5. Actual Weight Programs
320. If the operator decides to use an actual weights program,
how might it determine the actual weight of passengers?
321. If the operator decides to use an actual weight program,
how should it determine the actual weights of personal items and
bags?
322. What approach should an operator use to record actual
weights?
Chapter 4. Operator Reporting Systems and FAA Oversight
Section 1. Pilot and Agent Reporting Systems
400. What are the pilots' and operators' responsibilities in
reporting aircraft loading and manifest preparation discrepancies?
Section 2. FAA Oversight
401. Which FAA inspectors are responsible for overseeing an
operator's weight and balance program?
402. Which portions of OpSpecs or MSpecs are relevant to an
operator's weight and balance program?
403. When will the FAA revise the standard average weights in
this AC?
Appendix 1. Definitions
Appendix 2. Source of Standard Average Weights in This AC
1. Standard average passenger weights.
2. Standard average bag weights.
Table 2-1. Bag Survey Results
Appendix 3. Sample Operational Loading Envelope
1. Introduction.
2. Assumptions for this example.
Figure 3-1. Sample Aircraft Interior Seating Diagram
3. Curtailments for passenger seating variation.
Table 3-1. Calculation of Zone 1 Centroid
Table 3-2. Calculation of Zone 2 Centroid
Table 3-3. Calculation of Zone 3 Centroid
Table 3-4. Moments Resulting from the Zone Centroid Assumption
for Zone 1
Table 3-5. Moments Resulting from the Window-Aisle-Remaining
Assumption for Zone 1
Table 3-6. Comparison of Moments for Zone 1
Table 3-7. Moments Resulting from the Zone Centroid Assumption
for Zone 2
Table 3-8. Moments Resulting from the Window-Aisle-Remaining
Assumption for Zone 2
Table 3-9. Comparison of Moments for Zone 2
Table 3-10. Moments Resulting from the Zone Centroid Assumption
for Zone 3
Table 3-11. Moments Resulting from the Window-Aisle-Remaining
Assumption for Zone 3
Table 3-12. Comparison of Moments for Zone 3
4. Other curtailments to the manufacturer's loading envelope.
5. Operational loading envelope diagrams.
Figure 3-2. Operational Loading Envelope with a Curtailment for
Variations in Passenger Seating
Figure 3-3. Operational Loading Envelope Using Actual Seating
Location of Passengers
Appendix 4. Additional Curtailments to CG Envelopes to Account for
Variations to Passenger Weights
Table 4-1. Row Factor
Table 4-2. Sample Curtailment Due to Variations in Passenger
Weight and Male/Female Ratio Using Window-Aisle Method
Appendix 5. Options to Improve Accuracy
Figure 5-1. Sample Aircraft Interior Seating Diagram
Figure 5-2. Sample Passenger Seating Moment
Figure 5-3. Sample Passenger Seating Moment
Figure 5-4. Sample Passenger Seating Moment
Appendix 6. Sample CG Envelope Development
Figure 6-1. Operational CG Envelope--3 Passenger Cabin Zones
Figure 6-2. Operational CG Envelope--Actual Passenger Seating
Appendix 7. Checklist
[[Page 51510]]
Chapter 1. Introduction
100. What Is the Purpose of This Advisory Circular (AC)?
a. This AC provides operators with guidance on how to develop and
receive approval for a weight and balance control program for aircraft
operated under Title 14 of the Code of Federal Regulations (14 CFR)
part 91, subpart K of part 91, and parts 121, 125, and 135.
b. This AC presents recommendations for an acceptable means, but
not the only means, to develop and receive approval for a weight and
balance control program, and includes guidance for using average and
estimated weights in accordance with part 121, section 121.153(b) and
other applicable parts of subpart K of part 91 and parts 121, 125, and
135.
Note: Per part 125, section 125.91(b), no person may operate an
airplane in a part 125 operation unless the current empty weight and
center of gravity (CG) are calculated from the values established by
actual weighing of the airplane within the preceding 36 calendar-
months.
c. If an operator adopts the suggestions contained in this AC, the
operator must ensure that, when appropriate, it replaces discretionary
language such as ``should'' and ``may'' with mandatory language in
relevant manuals, operations specifications (OpSpecs), or management
specifications (MSpecs).
101. How Is This AC Organized?
This AC has four main chapters and seven appendixes. Chapter 1
contains general information about this AC and background. Chapter 2
addresses aircraft weighing and loading schedules. Chapter 3 describes
different methods to determine the weight of passengers and bags.
Chapter 4 addresses the Federal Aviation Administration's (FAA) role in
developing and approving an operator's weight and balance control
program. Finally, appendixes 1 through 7 contain technical information
such as definitions, the source of data used in the AC, a sample
loading envelope, an example of curtailments to the loading envelope,
suggestions to improve accuracy, sample CG envelope development, and
checklists for operators.
102. What Documents Does This AC Cancel?
This AC cancels--
a. AC 120-27C, Aircraft Weight and Balance Control, dated November
7, 1995; and
b. Joint Handbook Bulletin for Airworthiness (HBAW) 95-14 and Air
Transportation (HBAT) 95-15, Adherence to Advisory Circular 120-27C,
``Aircraft Weight and Balance Control,'' dated November 17, 1995.
103. What Should an Operator Consider While Reading This AC?
a. Accurately calculating an aircraft's weight and CG before flight
is essential to comply with the certification limits established for
the aircraft. These limits include both weight and CG limits. By
complying with these limits and operating under the procedures
established by the manufacturer, an operator is able to meet the weight
and balance requirements specified in the aircraft flight manual (AFM).
Typically, an operator calculates takeoff weight by adding the
operational empty weight (OEW) of the aircraft, the weight of the
passenger and cargo payload, and the weight of fuel. The objective is
to calculate the takeoff weight and CG of an aircraft as accurately as
possible.
b. When using average weights for passengers and bags, the operator
must be vigilant to ensure that the weight and balance control program
reflects the reality of aircraft loading. The FAA will periodically
review the guidance in this AC and update this AC if average weights of
the traveling public should change or if regulatory requirements for
carry-on bags or personal items should change. Ultimately, the operator
is responsible for determining if the procedures described in this AC
are appropriate for use in its type of operation.
104. Who Should Use This AC?
a. This document provides guidance to operators that are either
required to have an approved weight and balance control program under
parts 121 and 125, or choose to use average aircraft, passenger or
baggage weights when operating under subpart K of part 91 or part 135.
The guidance in this AC is useful for anyone involved in developing or
implementing a weight and balance control program.
b. As shown in Table 1-1, the FAA has divided aircraft into three
categories for this AC to provide guidance appropriate to the size of
the aircraft.
Table 1-1.--Aircraft Cabin Size
------------------------------------------------------------------------
For this AC, an aircraft originally type-
certificated with-- Is considered--
------------------------------------------------------------------------
71 or more passenger seats................ A large-cabin aircraft.
30 to 70 passenger seats.................. A medium-cabin aircraft.
5 to 29 passenger seats................... A small-cabin aircraft.
0 to 4 passenger seats.................... Not eligible.
------------------------------------------------------------------------
105. Who Can Use Standard Average or Segmented Weights?
a. Standard Average Weights. Use of standard average weights is
limited to operators of multiengine turbine-powered aircraft originally
type-certificated for five (5) or more passenger seats who hold a
letter of authorization (LOA), OpSpecs, or MSpecs, as applicable, and
were certificated under 14 CFR part 25, 29, or part 23 commuter
category or the operator and manufacturer is able to prove that the
aircraft can meet the performance requirements of subpart B of part 25.
Single-engine and multiengine turbine Emergency Medical Service
Helicopter (EMS/H) operators may use standard average weights for EMS
operations, provided they have received an LOA.
b. Segmented Weights. Use of segmented weights is limited to those
aircraft that meet the requirements of paragraph 105(a) or that are
multiengine turbine-powered aircraft originally type-certificated for
five (5) or more passenger seats and that do not meet the performance
requirements of subpart B of part 25. Segmented passenger weights are
listed in Chapter 3, Table 3-5.
Chapter 2. Aircraft Weights and Loading Schedules
Section 1. Establishing Aircraft Weight
200. How Does an Operator Establish the Initial Weight of an Aircraft?
Prior to being placed into service, each aircraft should be weighed
and the empty weight and CG location established. New aircraft are
normally weighed at the factory and are eligible to be placed into
operation without reweighing if the weight and balance records were
adjusted for alterations and modifications to the aircraft and if the
cumulative change to the weight and balance log is not more than plus
or minus one-half of one percent (0.5 percent) of the maximum landing
weight or the cumulative change in the CG position exceeds one-half of
one percent (0.5 percent) of the mean aerodynamic chord. Aircraft
transferred from one operator that has an approved weight and balance
program, to another operator with an approved program, need not be
weighed prior to use by the
[[Page 51511]]
receiving operator unless more than 36 calendar-months have elapsed
since last individual or fleet weighing, or unless some other
modification to the aircraft warrants that the aircraft be weighed
(e.g., paragraph 203(c)). Aircraft transferred, purchased, or leased
from an operator without an approved weight and balance program, and
that have been unmodified or only minimally modified, can be placed
into service without being reweighed if the last weighing was
accomplished by a method established through an operator's approved
weight and balance control program within the last 12 calendar-months
and a weight and balance change record was maintained by the operator.
See paragraph 203(c) for a discussion of when it may be potentially
unsafe to fail to reweigh an aircraft after it has been modified.
201. How Does an Operator Document Changes to an Aircraft's Weight and
Balance?
The weight and balance system should include methods, such as a
log, ledger, or other equivalent electronic means by which the operator
will maintain a complete, current, and continuous record of the weight
and CG of each aircraft. Alterations and changes affecting either the
weight and/or balance of the aircraft should be recorded in this log.
Changes to an aircraft that result in a weight being added to the
aircraft, weight being removed from the aircraft, or weight being
relocated in or on the aircraft should be recorded in such a log.
Changes in the amount of weight or in the location of weight in or on
the aircraft should be recorded whenever the weight change is at or
exceeds the weights listed in Table 2-1.
Table 2-1.--Incremental Weight Changes That Should Be Recorded in a
Weight and Balance Change Record
------------------------------------------------------------------------
An operator should record
In the weight change record of a-- any weight changes of--
------------------------------------------------------------------------
Large-cabin aircraft...................... +/-10 lb or greater.
Medium-cabin aircraft..................... +/-5 lb or greater.
Small-cabin aircraft...................... +/-1 lb or greater.
------------------------------------------------------------------------
202. How Does the Operator Maintain the OEW?
The loading schedule may utilize the individual weight of the
aircraft in computing operational weight and balance or the operator
may choose to establish fleet empty weights for a fleet or group of
aircraft.
a. Establishment of OEW. The OEW and CG position of each aircraft
should be reestablished at the reweighing periods discussed in
paragraph 203. In addition, it should be reestablished whenever the
cumulative change to the Weight and Balance Log is more than plus or
minus one-half of 1 percent (0.5 percent) of the maximum landing
weight, or whenever the cumulative change in the CG position exceeds
one-half of 1 percent (0.5 percent) of the mean aerodynamic chord
(MAC). In the case of helicopters and airplanes that do not have a MAC-
based CG envelope (e.g., canard equipped airplane), whenever the
cumulative change in the CG position exceeds one-half of 1 percent (0.5
percent) of the total CG range, the weight and balance should be
reestablished.
b. Fleet Operating Empty Weights (FOEW). An operator may choose to
use one weight for a fleet or group of aircraft if the weight and CG of
each aircraft is within the limits stated above for establishment of
OEW. When the cumulative changes to an aircraft Weight and Balance Log
exceed the weight or CG limits for the established fleet weight, the
empty weight for that aircraft should be reestablished. This may be
done by moving the aircraft to another group, or reestablishing new
FOEWs.
203. How Often Are Aircraft Weighed?
a. Individual Aircraft Weighing Program. Aircraft are normally
weighed at intervals of 36 calendar-months. An operator may, however,
extend this weighing period for a particular model aircraft when
pertinent records of actual routine weighing during the preceding
period of operation show that weight and balance records maintained are
sufficiently accurate to indicate that aircraft weights and CG
positions are within the cumulative limits specified for establishment
of OEW, (see paragraph 202). Such applications should be substantiated
in each instance with at least two aircraft weighed. Under an
individual aircraft weighing program, an increase should not be granted
which would permit any aircraft to exceed 48 calendar-months since the
last weighing, including when an aircraft is transferred from one
operator to another. In the case of helicopters, increases should not
exceed a time that is equivalent to the aircraft overhaul period.
Note: Per part 125, section 125.91(b), no person may operate an
airplane in a part 125 operation, unless the current empty weight
and center of gravity (CG) are calculated from the values
established by actual weighing of the airplane within the preceding
36 calendar-months.
b. Fleet Weighing. An operator may choose to weigh only a portion
of the fleet and apply the unaccounted weight and moment change
determined by this sample to the remainder of the fleet.
(1) A fleet is composed of a number of aircraft of the same model
(For example, B747-200s in a passenger configuration and B747-200
freighters should be considered different fleets. Likewise, B757-200s
and B757-300s should be considered different fleets). The primary
purpose of defining a fleet is to determine how many aircraft should be
weighed in each weighing cycle. A fleet may be further divided into
groups to establish FOEWs.
Table 2--2. Number of Aircraft To Weigh in a Fleet
------------------------------------------------------------------------
An operator must weigh (at
For fleets of-- minimum)--
------------------------------------------------------------------------
1 to 3 aircraft........................... All aircraft.
4 to 9 aircraft........................... 3 aircraft, plus at least 50
percent of the number of
aircraft greater than 3.
More than 9 aircraft...................... 6 aircraft, plus at least 10
percent of the number of
aircraft greater than 9.
------------------------------------------------------------------------
(2) In choosing the aircraft to be weighed, the aircraft in the
fleet having the most hours flown since last weighing should be
selected.
(3) An operator should establish a time limit such that all
aircraft in a fleet are eventually weighed. Based on the length of time
that a fleet of aircraft typically remains in service with an operator,
the time limit should not exceed 18 years (six 3-year weighing cycles).
It is not intended that an operator be required to weigh any remaining
aircraft in the event that business conditions result in retirement of
a fleet before all aircraft have been weighed.
c. Weighing Aircraft--Modifications. For most aircraft
modifications, computing the weight and balance changes is practical.
For some modifications, such as interior reconfigurations, the large
number of parts removed, replaced, and installed make an accurate
determination of the weight and balance change by computation
impractical. It would be potentially unsafe to fail to reestablish the
aircraft weight and balance, by actually reweighing the aircraft, in
situations where the cumulative net change in the weight and balance
log exceeds:
(1) In the case of airplanes, plus or minus one-half of 1 percent
(0.5
[[Page 51512]]
percent) of the maximum landing weight, or whenever the cumulative
change in the CG position exceeds one-half of 1 percent (0.5 percent)
of the MAC.
(2) In the case of helicopters and airplanes that do not have a
MAC-based CG envelope (e.g., canard equipped airplane), whenever the
cumulative change in the CG position exceeds one-half of 1 percent (0.5
percent) of the total CG range.
Note: In the situations specified in paragraphs 203c(1) and (2),
the operator should weigh two or more aircraft in a fleet, as
required in Table 2-2, to get consistent results. The operator may
choose to weigh the aircraft before and after the modification, or
just after the modification.
204. What Procedures Should Be Used to Weigh Aircraft?
a. An operator should take precautions to ensure that it weighs an
aircraft as accurately as possible. These precautions include checking
to ensure that all required items are aboard the aircraft and the
quantity of all fluids aboard the aircraft is considered. An operator
should weigh aircraft in an enclosed building because scale readings
stabilize faster in the absence of drafts from open doors.
b. An operator should establish and follow instructions for
weighing the aircraft that are consistent with the recommendations of
the aircraft manufacturer and scale manufacturer. The operator should
ensure that all scales are certified and calibrated by the manufacturer
or a certified laboratory, such as a civil department of weights and
measures, or the operator may calibrate the scale under an approved
calibration program. The operator should also ensure that the scale is
calibrated within the manufacturer's recommended time period, or time
periods, as specified in the operator's approved calibration program.
Section 2. Aircraft Loading Schedules
205. What is a Loading Schedule?
a. The loading schedule is used to document compliance with the
certificated weight and balance limitations contained in the
manufacturer's AFM and weight and balance manual.
b. The loading schedule is developed by the operator based on its
specific loading calculation procedures and provides the operational
limits for use with the operator's weight and balance program approved
under this AC. These approved operational limits are typically more
restrictive but do not exceed the manufacturer's certificated limits.
This is because the loading schedule is generally designed to check
only specific conditions (e.g., takeoff and zero fuel) known prior to
takeoff, and must account for variations in weight and balance in
flight. It must also account for factors selected to be excluded, for
ease of use, from the calculation process. Loading the aircraft so that
the calculated weight and balance is within the approved limits will
maintain the actual weight and balance within the certificated limits
throughout the flight.
c. Development of a loading schedule represents a trade-off between
ease of use and loading flexibility. A schedule can provide more
loading flexibility by requiring more detailed inputs, or it can be
made easier to use by further limiting the operational limits to
account for the uncertainty caused by the less detailed inputs.
d. Several types of loading schedules are commonly-used, including
computer programs as well as ``paper'' schedules, which can be either
graphical, such as an alignment (``chase around chart'') system, slide
rule, or numerical, such as an adjusted weight or index system.
e. It is often more convenient to compute the balance effects of
combined loads and to display the results by using ``balance units'' or
``index units.'' This is done by adding the respective moments (weight
times arm) of each item. Graphing the moments results in a ``fan grid''
where lines of constant balance arms (BA) or % MAC are closer together
at lower weights and further apart at higher weights. Direct graphical
or numerical addition of the balance effects are possible using these
moment values.
f. To make the magnitude of the numbers more manageable, moments
can be converted to an index unit. For example:
[GRAPHIC] [TIFF OMITTED] TN19AU04.001
Note: Where datum is the reference BA that will plot as a
vertical line on the fan grid, M and K are constants that are
selected by the operator. M is used to scale the index values, and K
is used to set the index value of the reference BA.
206. How Should an Operator Determine the Weight of Each Fluid Used
Aboard the Aircraft?
An operator should use one of the following:
a. The actual weight of each fluid,
b. A standard volume conversion for each fluid, or
c. A volume conversion that includes a correction factor for
temperature.
Section 3. Constructing a Loading Envelope
207. What Should an Operator Consider When Constructing a Loading
Envelope?
Each operator complying with this AC must construct a ``loading
envelope'' applicable to each aircraft being operated. The envelope
will include all relevant weight and balance limitations. It will be
used to ensure that the aircraft is always operated within appropriate
weight and balance limitations, and will include provisions to account
for the loading of passengers, fuel, and cargo; the in-flight movement
of passengers, aircraft components, and other loaded items; and the
usage or transfer of fuel and other consumables. The operator must be
able to demonstrate that the aircraft is being operated within its
certificated weight and balance limitations using reasonable
assumptions that are clearly stated.
208. What Information From the Aircraft Manufacturer Should an Operator
Use?
The construction of the loading envelope will begin with the weight
and balance limitations provided by the aircraft manufacturer in the
weight and balance manual, type certificate data sheet, or similar
approved document. These limitations will include, at minimum, the
following items, as applicable:
a. Maximum zero-fuel weight.
b. Maximum takeoff weight.
c. Maximum taxi weight.
d. Takeoff and landing CG limitations.
e. In-flight CG limitations.
f. Maximum floor loadings-including both running and per square foot
limitations.
g. Maximum compartment weights.
h. Cabin shear limitations.
i. Any other limitations provided by the manufacturer.
209. What Should the Operator Consider When Curtailing the
Manufacturer's Loading Envelope?
a. The operator should curtail the manufacturer's loading
limitations to account for loading variations and in-flight movement
that are encountered in normal operations. For example, if passengers
are expected to move about the cabin in flight, the operator must
curtail the manufacturer's CG envelope by an amount necessary to ensure
that movement of passengers does not take the aircraft outside its
certified envelope. If the aircraft is loaded within the new, curtailed
envelope, it will always be operated within the manufacturer's
envelope, even though some of the loading parameters, such as
[[Page 51513]]
passenger seating location, are not precisely known.
b. In some cases an aircraft may have more than one loading
envelope for preflight planning and loading. Each envelope must have
the appropriate curtailments applied for those variables that are
expected to be relevant for that envelope. For example, an aircraft
might have separate takeoff, in-flight, and landing envelopes.
Passengers are expected to remain seated in the cabin during take-off
or landing. Therefore, the takeoff and landing envelope need not be
curtailed for passenger movement.
c. Upon determination of the curtailed version of each envelope,
the most restrictive points (for each condition the operator's program
will check) generated by an ``overlay'' of the envelopes will form the
aircraft operational envelopes. These envelopes must be observed. By
restricting operation to these ``operational envelopes,'' compliance
with the manufacturer's certified envelope will be ensured in all
phases of flight, based upon the assumptions within the curtailment
process. Optionally, an operator may choose to not combine the
envelopes but observe each envelope independently. However, due to
calculation complexity, this is typically only possible through
automation of the weight and balance calculation.
210. What Are Some Examples of Common Curtailments to the
Manufacturer's Loading Envelope?
The following subparagraphs provide examples of common loading
curtailments. They are only examples. Operators using an approved
weight and balance control program must include curtailments
appropriate to the operations being conducted. Each of the items
mentioned below is a single curtailment factor. The total curtailment
of the manufacturer's envelope is computed by combining the
curtailments resulting from each of these factors.
a. Passengers. The operator must account for the seating of
passengers in the cabin. The loading envelope need not be curtailed if
the actual seating location of each passenger is known. If assigned
seating is used to determine passenger location, the operator must
implement procedures to ensure that the assignment of passenger seating
is incorporated into the loading procedure. It is recommended that the
operator take into account the possibility that some passengers may not
sit in their assigned seats.
(1) If the actual seating location of each passenger is not known,
the operator may assume that all passengers are seated uniformly
throughout the cabin or a specified subsection of the cabin. If this
assumption is made, the operator must curtail the loading envelope to
account for the fact that the passenger loading may not be uniform. The
curtailment may make reasonable assumptions about the manner in which
people distribute themselves throughout the cabin. For example, the
operator may assume that window seats are occupied first, followed by
aisle seats, followed by the remaining seats (window-aisle-remaining
seating). Both forward and rear loading conditions should be
considered. That is, the passengers may fill up the window, aisle, and
remaining seats from the front of the aircraft to the back, or the back
to the front.
(2) If necessary, the operator may divide the passenger cabin into
subsections or ``zones'' and manage the loading of each zone
individually. It can be assumed that passengers will be sitting
uniformly throughout each zone, as long as the curtailments described
in the previous paragraph are put in place.
(3) All such assumptions should be adequately documented.
b. Fuel. The operator's curtailed loading envelope must account for
the effects of fuel. The following are examples of several types of
fuel-related curtailments:
(1) Fuel density. A certain fuel density may be assumed and a
curtailment included to account for the possibility of different fuel
density values. Fuel density curtailments only pertain to differences
in fuel moment caused by varying fuel volumes, not to differences in
total fuel weight. The fuel gauges in most transport category aircraft
measure weight, not volume. Therefore, the indicated weight of the fuel
load can be assumed to be accurate.
(2) Fuel movement. The movement or transfer of fuel in flight.
(3) Fuel usage in flight. The burning of fuel may cause the CG of
the fuel load to change. A curtailment may be included to ensure that
this change does not cause the CG of the aircraft to move outside of
the acceptable envelope.
c. Fluids. The operator's curtailed CG envelope must account for
the effects of galley and lavatory fluids. These factors include such
things as:
(1) Use of potable water in flight.
(2) Movement of water or lavatory fluids.
d. In-Flight Movement of Passenger and Crew. The operational
envelope must account for the in-flight movement of passengers, crew,
and equipment. This may be done by including a curtailment equal to the
moment change caused by the motion being considered. It may be assumed
that all passengers, crew, and equipment are secured when the aircraft
is in the takeoff or landing configuration. Standard operational
procedures may be taken into account. Examples of items that can move
during flight are:
(1) Flight deck crewmembers moving to the lavatory. Flight deck
crewmembers may move to the most forward lavatory in accordance with
the security procedures prescribed for crews leaving the cockpit. An
offsetting credit may be taken if another crewmember moves to the
flight deck during such lavatory trip.
(2) Flight attendants moving throughout the cabin.
(3) Service carts moving throughout the cabin. Operators should
take their standard operating procedures into account. If procedures do
not dictate otherwise, it should be assumed that the service carts can
travel anywhere within the compartment to which they are assigned. If
multiple carts are in a given compartment, and no restrictions are
placed on their movement, then the maximum number of carts, moving the
maximum distance, must be considered. The weight of the number of
flight attendants assigned to each cart must also be considered. The
assumed weight of each cart may be the maximum anticipated cart-load or
the maximum design load, as appropriate to the operator's procedures.
(4) Passengers moving throughout the cabin. Allowances should be
made for the possibility that passengers may move about the cabin in
flight. The most common would be movement to the lavatory, described
below. If a lounge or other passenger gathering area is provided, the
operator should assume that passengers move there from the centroid of
the passenger cabin(s). The maximum capacity of the lounge should be
taken into account.
(5) Passengers moving to the lavatory. Operators should account for
the CG change caused by passengers moving to the lavatory. Operators
should develop reasonable scenarios for the movement of passengers in
their cabins and consider the CG shifts that can be expected to occur.
Generally, it may be assumed that passengers to move to the lavatories
closest to their seats. In aircraft with a single lavatory, movement
from the ``most adverse'' seat must be taken into account. Assumptions
may be made which reflect operator lavatory and seating policies. For
example, it may be assumed that coach passengers may only use the
lavatories in the coach
[[Page 51514]]
cabin, if that is the operator's normal policy.
e. Movement of Flaps and Landing Gear. If the manufacturer has not
already done so, the operator must account for the movement of landing
gear, flaps, wing leading edge devices, or any other moveable
components of the aircraft. Devices deployed only while in contact with
the ground, such as ground spoilers or thrust reversers, may be
excluded from such curtailments.
f. Baggage and Freight. It can be assumed that baggage and freight
may be loaded at the centroid of each baggage compartment. Operators do
not need to include a curtailment if procedures are used which ensure
that the cargo is loaded uniformly throughout each compartment.
Section 4. Automated Weight and Balance Systems
211. How does an onboard weight and balance system compare to a
conventional weight buildup method?
a. An operator may use an onboard weight and balance system to
calculate an aircraft's weight and balance, provided the FAA has
approved the system for use in an operator's weight and balance control
program. This section discusses the differences an operator should
consider when using an onboard weight and balance system compared to a
conventional weight buildup method. This section addresses only the
operational considerations related to the use of an FAA-authorized
onboard weight and balance system.
b. Like operators using a conventional weight buildup method to
calculate weight and balance, an operator using an onboard weight and
balance system as a primary weight and balance control system should
curtail the manufacturer's loading envelope to ensure the aircraft does
not exceed the manufacturer's certificated weight and CG limits.
However, an operator using an onboard weight and balance system would
not need to curtail the loading envelope for assumptions about
passenger and bag weight or distribution.
c. Because an onboard weight and balance system measures the actual
weight and CG location of an aircraft, an operator may not need to
include certain curtailments to the loading envelope to account for
variables such as passenger seating variation or variation in passenger
weight. However, an operator should curtail the loading envelope for
any system tolerances that may result in CG or weight errors. Using an
onboard weight and balance system does not relieve an operator from the
requirement to complete and maintain a load manifest.
212. What measures should an operator take to obtain operational
approval for an onboard weight and balance system?
a. System calibration. An operator should develop procedures to
calibrate its onboard weight and balance system equipment periodically
in accordance with the manufacturer's instructions. An operator may
calibrate its system with operational items or fuel aboard the aircraft
to test the system at a representative operational weight. However, an
operator may not use an onboard weight and balance system in place of
procedures described in Section 1 of this chapter for weighing the
aircraft to establish OEW or CG location.
b. Demonstration of system accuracy. As part of the operational
approval process, an operator should demonstrate that its onboard
weight and balance system maintains its certificated system accuracy
between calibration periods. An operator should not have to conduct
this demonstration more than once for installing a specific system on
one type of aircraft. For the demonstration, the operator should use an
aircraft in normal operational service, or in operations that represent
the expected environmental and operational conditions in which the
aircraft will operate.
213. What operational considerations should an operator take into
account when using an onboard weight and balance system?
a. Certification limits. An operator using an onboard weight and
balance system as its primary means of calculating weight and balance
should have procedures in place to ensure that the system is operated
within the limits established during the system's certification
process.
b. Environmental considerations. An operator using an onboard
weight and balance system should ensure that it uses the system within
the environmental limits established by the manufacturer. Environmental
conditions that may affect the performance of an onboard weight and
balance system include temperature, barometric pressure, wind, ramp
slope, rain, snow, ice, frost, dew, deicing fluid, etc.
c. Aircraft considerations. An operator using an onboard weight and
balance system should ensure the weight and CG measured by the system
are not affected by the aircraft configuration, such as the movement of
flaps, stabilizers, doors, stairways or jetways, or any connections to
ground service equipment. Other factors that an operator should
consider include engine thrust, oleo strut extension, and aircraft taxi
movement.
d. Takeoff trim settings. If the aircraft manufacturer provides
trim settings for takeoff based on the aircraft's CG location, an
operator using an onboard weight and balance system should ensure that
the onboard weight and balance system provides flight crewmembers with
adequate information to determine the appropriate trim setting.
e. Operational envelope. The operational envelope for onboard
weight and balance systems shall be developed using the same procedures
described in other parts of this AC, with the exception that the
operational envelope need not be curtailed for passenger random seating
and passenger weight variance. Also note that the fuel load is
subtracted from the measured takeoff weight to determine the zero fuel
weight and CG, instead of being added to the zero fuel weight as part
of the load buildup. In addition, an operator must curtail the CG
envelope for any system CG tolerance and the weight must be curtailed
for any system tolerance above 1 percent.
f. Complying with compartment or unit load device (ULD) load
limits. When using an onboard weight and balance system, an operator
should develop in its weight and balance control program a method to
ensure that it does not exceed the load limits specified for a
compartment or ULD. If an operator develops appropriate procedures, an
operator may request approval to exclude bag counts from its load
manifest. The following are two examples of acceptable means to
demonstrate compliance with compartment load limits.
(1) An operator may assign a standard average weight to bags. Based
on that standard average weight, the operator may place a placard in
each compartment stating the maximum number of bags permitted. An
operator may also create a table that lists the total weight associated
with a given number of bags to ensure the operator does not exceed the
load limit of a compartment or ULD.
(2) By conducting sample loadings, an operator may demonstrate that
the average density of the bags it places in a compartment or ULD would
not allow it to exceed the compartment or ULD load limits
inadvertently.
[[Page 51515]]
214. May an operator use the information in this AC to develop a backup
system?
An operator using an onboard weight and balance system as its
primary means of calculating weight and balance may use the guidance in
this AC to develop a backup system based on a conventional weight
buildup. If an operator develops and receives approval for a backup
system, the FAA may grant the operator relief to include an onboard
weight and balance system in the operator's minimum equipment list.
215. What operational considerations should an operator take into
account when using a computerized weight and balance system?
a. An operator may use an installed computerized weight and balance
system to calculate the load schedule for the aircraft's weight and
balance for primary dispatch, provided that the system received
certification and operational approval for use in an operator's
approved weight and balance control program. The system consists of a
computer program that runs on installed Electronic Flight Bag computing
devices or the Aircraft Communication Addressing and Reporting System,
and can be downloaded to ground operations via electronic links. The
system displays the load sheet to the pilot or flight operations for
primary dispatch.
b. Like operators using a conventional weight buildup method to
calculate weight and balance, an operator may use the computerized
weight and balance system to provide the FAA approved loading
schedules. The operator who uses the computerized weight and balance
system as part of its approved weight and balance program should meet
all provisions pertinent to the operator's approved weight and balance
program as described in this AC.
Chapter 3. Methods to Determine the Weight of Passengers and Bags
Section 1. Choosing the Appropriate Method
300. What should an operator consider when choosing the appropriate
method?
a. For many years, operators of transport category aircraft have
used average weights for passengers and bags to calculate an aircraft's
weight and balance, in accordance with standards and recommended
practices. This method eliminates many potential sources of error
associated with accounting for a large number of relatively light
weights. However, differences between the actual weight of passengers
and bags and the average weight of passengers and bags can occur when
using average weights.
b. Statistical probability dictates that the smaller the sample
size (i.e., cabin size), the more the average of the sample will
deviate from the average of the larger universe. Because of this, the
use of standard average passenger weights in weight and balance
programs for small and medium cabin aircraft should be examined in
greater detail.
c. The next four sections describe four methods available to
operators to determine passenger and bag weight. They are standard
average weights in Section 2; average weights based on survey results
in Section 3; segmented weights in Section 4; and actual weights in
Section 5. An operator should review the following discussion and
consult Table 3-1 to determine which method or methods are appropriate
to its type of operation.
d. Large Cabin Aircraft. Operators of large cabin aircraft may use
the standard average weights for passengers and bags. If an operator
determines that the standard average weights are not representative of
its operation for some route or regions, it is encouraged to conduct a
survey as detailed in Section 3 of this chapter, to establish more
appropriate average weights for its operation. Operators should have
procedures for identifying situations that would require the use of
nonstandard or actual weights.
e. Medium Cabin Aircraft. Medium cabin aircraft should be evaluated
to determine if the aircraft should be treated more like large or small
cabin aircraft. To determine if a medium cabin aircraft can be treated
as a large cabin aircraft, the aircraft must meet either both of the
loadability criteria or the loading schedule criteria or else be
subject to the small cabin weights and curtailments:
Loadability Criteria:
The CG of the OEW is within the manufacturer's loading
envelope, and
The CG of the zero fuel weight is within the
manufacturer's loading envelope when loaded with a full load of
passengers and all cargo compartments are filled with a density of 10
pounds per cubic foot.
Or
Loading Schedule Criteria:
The operator must use a loading schedule based upon zones.
The aircraft cabin may have no more than four rows per zone with not
less than four zones.
f. Small Cabin Aircraft. Operators of small cabin aircraft may
request approval to use any one of the following methods when
calculating the aircraft weight and balance.
(1) The operator may use actual passenger and bag weights, or
(2) The operator may use the segmented passenger weights listed in
Table 3-5 and average bag weights listed in Section 2 of this chapter,
or
(3) The operator may use the standard average passenger and bag
weights prescribed for large cabin aircraft, or average weights based
on an FAA-accepted survey, if--
(a) The aircraft was certificated under part 23 commuter category,
part 25, or part 29 (or is able to prove an aircraft has equivalent
part 25 or 29 performance data), and
(b) The operator curtails the aircraft CG envelope as prescribed in
Appendixes 3 and 4 of this AC.
Section 2. Standard Average Weights
301. What standard average passenger weights should an operator with an
approved carry-on bag program use?
a. The standard average passenger weights provided in Table 3-1
were established based on data from U.S. Government health agency
surveys. For more background information on the source of these
weights, refer to Appendix 2.
b. The standard average passenger weights in Table 3-1 include 5
pounds for summer clothing, 10 pounds for winter clothing, and a 16-
pound allowance for personal items and carry-on bags. Where no gender
is given, the standard average passenger weights are based on the
assumption that 50 percent of passengers are male and 50 percent of
passengers are female.
[[Page 51516]]
[GRAPHIC] [TIFF OMITTED] TN19AU04.002
c. An operator may use summer weights from May 1 to October 31 and
winter weights from November 1 to April 30. However, these dates may
not be appropriate for all routes or operators. For routes with no
seasonal variation, an operator may use the average weights appropriate
to the climate. Use of year-round average weights for operators with
seasonal variation should avoid using an average weight that falls
between the summer and winter average weights. Operators with seasonal
variation that elect to use a year-round average weight should use the
winter average weight. Use of seasonal dates, other than those listed
above, will be entered as nonstandard text and approved through the
operator's OpSpec, MSpec, or LOA, as applicable.
d. The standard average weights listed in Table 3-1 are based on
the assumption that the operator has a carry-on bag program. Operators
using a no-carry-on bag program should refer to paragraph 305 of this
section.
Note: The weight of children under the age of 2 has been
factored into the standard average and segmented adult passenger
weights.
302. What standard average weights should an operator use for carry-on
bags and personal items?
a. An operator using standard average passenger weights should
include the weight of carry-on bags and personal items in the
passenger's weight. The standard average passenger weights in Table 3-1
include a 16-pound allowance for personal items and carry-on bags,
based on the assumption that--
(1) One-third of passengers carry one personal item and one carry-
on bag.
(2) One-third of passengers carry one personal item or carry-on
bag.
(3) One-third of passengers carry neither a personal item nor a
carry-on bag.
(4) The average weight allowance of a personal item or a carry-on
bag is 16 pounds.
b. If an operator believes the 16-pound allowance for personal
items and carry-on bags is not appropriate for its operations or
receives notification from the FAA that the assumptions provided in
paragraph 302a are not consistent with the operator's approved program,
the operator should conduct a survey to determine what percentage of
passengers carry personal items or carry-on bags aboard the aircraft.
An example of how to adjust the personal item and carry-on bag
allowance, based on the results of a survey, is in Section 3. An
operator should not use an allowance of less than 16 pounds for
personal items and carry-on bags unless the operator conducts a survey
or unless the operator has a no-carry-on bag program.
303. What standard average weights should an operator use for checked
bags?
An operator that chooses to use standard average weights for
checked bags should use a standard average weight of at least 30
pounds. An operator that requests approval to use a standard average
weight of less than 30 pounds for checked bags should have current,
valid survey data to support a lesser weight. An operator also may
conduct a study to establish different standard average bag weights for
portions of its operation to account for regional, seasonal,
demographic, aircraft, or route variation. For example, an operator
could establish different standard average bag weights for domestic and
international routes.
a. Heavy bags. Heavy bags are considered any bag that weighs more
than 50 pounds but less than 100 pounds. An operator should account for
a heavy bag by using one of the following weights:
(1) A standard average weight of 60 pounds,
(2) An average weight based on the results of a survey of heavy
bags, or
(3) The actual weight of the heavy bag.
Note: An operator that uses ``double-counting'' to treat a heavy
bag as if it were two checked bags for weight purposes should ensure
the load manifest represents the actual number of bags for counting
purposes. An operator should have a system in place to ensure that
heavy bags are identified, although operators may not be required to
weigh heavy bags on a scale.
b. Non-luggage bags. A non-luggage bag is any bag that does not
meet the normal criteria for luggage. Examples include golf bags,
fishing equipment packages, wheelchairs and strollers in their
shipping configuration, windsurfing kits, boxed bicycles, etc. For
non-luggage bags, operators may use any appropriate combination of
actual weights, average weights based on survey results, or standard
average bag weights. Operators that wish to establish an average
weight for a particular type of non-luggage bag, such as a golf bag,
must conduct a survey in accordance with the procedures established
in Section 3 of this chapter. Operators also should establish a
method to calculate the effect on CG of a large non-luggage bag,
such as a surfboard, that may occupy more than one compartment on
the aircraft.
[[Page 51517]]
304. What standard average weight should an operator of large cabin
aircraft use for bags checked plane-side?
Operators with a carry-on bag program that use standard average
weights should account for the weight of each carry-on bag checked
plane-side as 30 pounds. An operator may request approval to use a
weight other than 30 pounds if the operator has current, valid survey
data to support a different average weight for plane-side-loaded bags.
305. What standard average weights should an operator of small and
medium cabin aircraft use, if it has a ``no-carry-on bag program?'
Note: A no-carry-on bag program is limited to small and medium
cabin aircraft. A no-carry-on bag program is a term of art created
for this AC. Associated with this program are certain standard
average weight credits and reductions. Nothing in this AC prevents
an operator of large cabin aircraft from having a no-carry-on bag
``policy;'' however, the acceptable standard bag weights for such
checked baggage for large cabin aircraft are outlined in paragraphs
303 and 304 above. Furthermore, the passenger weight credit
associated with a no-carry-on-bag program is limited to the small
and medium cabin aircraft.
a. An operator with a no-carry-on bag program may allow passengers
to carry only personal items aboard the aircraft. Because these
passengers do not have carry-on bags, an operator may use standard
average passenger weights that are 6 pounds lighter than those for an
operator with an approved carry-on bag program. See Table 3-2.
[GRAPHIC] [TIFF OMITTED] TN19AU04.003
b. An operator that has a no-carry-on bag program may account for a
plane-side loaded bag as 20 pounds. To receive authorization to use 20
pounds as the average weight for a plane-side loaded bag, an operator
should demonstrate that sufficient controls exist to ensure that
passengers do not bring carry-on bags aboard the aircraft. An operator
also should demonstrate that sufficient controls exist to ensure the
personal items brought aboard the aircraft can fit completely under a
passenger seat or in an approved stowage compartment.
c. If an operator discovers that a plane-side loaded bag should
have been treated as a checked bag, the operator should account for
that bag at the standard average weight of 30 pounds for a checked bag.
306. What are the standard average weights for crewmembers?
a. An operator may choose to use the standard crewmember weights
shown in Table 3-3 or conduct a survey to establish average crewmember
weights appropriate for its operation.
[GRAPHIC] [TIFF OMITTED] TN19AU04.028
[[Page 51518]]
b. The flight crewmember weights in Table 3-3 were derived from
weights listed on all first- and second-class medical certificates. The
flight crewmember weight with bags assumes that each flight crewmember
has one crewmember roller bag and one pilot flight bag.
c. The flight attendant weights in Table 3-3 were derived from
National Health and Nutrition Examination Survey (NHANES) data. (For
additional information on NHANES, see Appendix 2.) The flight attendant
weights with bags assume that each flight attendant has one crewmember
roller bag and one flight attendant kit.
d. An operator may include the weight of crewmembers in an
aircraft's OEW or add the weight to the load manifest prepared for each
flight.
307. What weights may be used for company materials and mail?
a. Company Material. An operator should use actual weights for
company material and aircraft parts carried aboard an aircraft.
b. Mail. An operator should use the weights provided with
manifested mail shipments to account for the weight of the mail. If an
operator has to separate a shipment of mail, the operator may make
actual estimates about the weight of the individual pieces, provided
the sum of the estimated weights is equal to the actual manifested
weight of the entire shipment.
308. What are the standard average weights for special passenger groups
that do not fit an operator's standard average weight profile?
a. Sports Teams.
(1) Actual passenger weights should be used for nonstandard weight
groups (sports teams, etc.) unless average weights have been
established for such groups by conducting a survey in accordance with
the procedures established in Section 3 of this chapter. When such
groups form only a part of the total passenger load, actual weights, or
established average weights for the nonstandard group, may be used for
such exception groups and average weights used for the balance of the
passenger load. In such instances, a notation should be made in the
load manifest indicating the number of persons in the special group and
identifying the group; e.g., football squad, etc.
(2) Roster weights may be used for determining the actual passenger
weight.
(3) A standard allowance of 16 pounds per person may be used to
account for carry-on and personal items as provided in the operator's
approved carry-on bag program.
(4) If the carry-on bags are representative of the operator's
profile but do not meet the number of bags authorized per person, the
operator may count bags and use a 16 pounds per bag allocation.
(5) Actual weights must be used in cases where the carry-on bags
are not representative of the operator's profile.
b. Groups that are predominantly male or female should use the
standard average weights for males or females provided in Table 3-1.
c. Military Groups. The Department of Defense (DOD) requires actual
passenger and cargo weights be used in computing the aircraft weight
and balance for all DOD charter missions. This requirement is specified
in DOD Commercial Air Carrier Quality and Safety requirements
(reference 32 CFR part 861, section 861.4(e)(3)(ix), as revised). FAA-
approved air carrier weight and balance control programs may be used to
account for carry-on/personal items for mixed loads of military and
their dependents (such as channel missions). For combat-equipped troop
charters, the Air Mobility Command (AMC) will provide guidance to
account for the additional weight. If aircraft operators perceive that
the weights provided are understated, they should seek confirmation of
the actual weights and should make reasonable upward estimations and
adjustments to those passenger and/or bag weights.
Section 3. Average Weights Based on Survey Results
309. What should an operator consider when designing a survey?
a. This section provides operators with an acceptable survey method
to use in determining average weights for a weight and balance control
program. This section also describes how an operator can conduct a
survey to count personal items and carry-on bags to determine an
appropriate allowance for those items to include in passenger weight.
In addition, an operator may use the methods described in this section
to conduct a survey to determine the percentage of male and female
passengers, to calculate an average passenger weight.
b. Surveys conducted correctly allow an operator to draw reliable
inferences about large populations based on relatively small sample
sizes. In designing a survey, an operator should consider--
(1) The sample size required to achieve the desired reliability,
(2) The sample selection process, and
(3) The type of survey (average weights or a count of items).
310. What sample sizes should an operator use?
Several factors must be considered when determining an adequate
sample size. The more varied the population, the larger the sample size
required to obtain a reliable estimate. Paragraph 311 provides a
formula to derive the absolute minimum sample size to achieve a 95-
percent confidence level. Table 3-4 has been provided for those
operators that wish to use calculations other than those listed in
paragraph 311. Table 3-4 provides the operator with an acceptable
number of samples that may be collected to obtain a 95-percent
confidence level and lists the tolerable error associated with each
category.
[[Page 51519]]
[GRAPHIC] [TIFF OMITTED] TN19AU04.004
311. When conducting a survey, can an operator collect a smaller sample
size than that published in Table 3-4?
If the operator has chosen to use a sample size that is smaller
than that provided in Table 3-4, the operator should collect a
sufficient number of samples to satisfy the following formulas:
[GRAPHIC] [TIFF OMITTED] TN19AU04.005
Where:
s is the standard deviation
n is the number of points surveyed
xj is the individual survey weights
x is the sample average
[GRAPHIC] [TIFF OMITTED] TN19AU04.006
Where:
e is the tolerable error
312. What sampling method should an operator use?
a. An operator conducting a survey must employ random sampling
techniques. Random sampling means that every member of a group has an
equal chance of being selected for inclusion in the sample. If an
operator conducts a survey that does not employ random sampling, the
characteristics of the selected sample may not be indicative of the
larger group as a whole. Because of this, any conclusions drawn from
such a survey may not be valid.
b. The following are two examples of random sampling methods that
an operator may find appropriate for the type of survey conducted. An
operator may also consult a basic textbook on statistics to determine
if another random sampling method is more appropriate.
(1) Simple random selection. An operator should assign a sequential
number to each item in a group (such as passengers waiting on a line or
bag claim tickets). Then the operator randomly selects numbers and
includes the item corresponding with the number in the sample. The
operator repeats this process until it has obtained the minimum sample
size.
(2) Systematic random selection. An operator should randomly select
an item in sequence to begin the process of obtaining samples. The
operator should then use a predetermined, systematic process to select
the remaining samples following the first sample. For example, an
operator selects the third person in line to participate in the survey.
The operator then selects every fifth person after that to participate
in the survey. The operator continues selecting items to include in the
sample until it has obtained the minimum sample size.
c. Regardless of the sampling method used, an operator has the
option of surveying each passenger and bag aboard the aircraft and
should always give a passenger the right to decline to participate in
any passenger or bag weight survey. If a passenger declines to
participate, the operator should select the next passenger based on the
operator's random selection method rather than select the next
passenger in a line. If a passenger declines to participate, an
operator should not attempt to estimate data for inclusion in the
survey.
313. What should an operator consider when developing a survey plan and
submitting it to the FAA?
a. Developing a survey plan. Before conducting a survey, an
operator should develop a survey plan. The plan should describe the
dates, times, and locations the survey will take place. In developing a
survey plan, the operator should consider its type of operation, hours
of operation, markets served, and frequency of flights on particular
routes. An operator should avoid conducting surveys on holidays unless
it has a valid reason to request the particular date.
b. Submitting the survey plan to the FAA. It is recommended that an
operator submit its survey plan to the FAA at least 2 weeks before the
survey is expected to begin. Before the survey begins, the operator's
principal inspectors (PI) will review the plan and work with the
operator to develop a mutually acceptable plan. During the survey, the
PI will oversee the survey process to validate the execution of the
survey plan. After the survey is complete, the PI will review the
survey results and issue the appropriate OpSpecs or MSpecs. Once a
survey begins, the operator should continue the survey until complete,
even if the initial survey data indicates that the average weights are
lighter or heavier than expected.
314. What general survey procedures should an operator use?
a. Survey locations. An operator should accomplish a survey at one
or more airports that represent at least 15 percent of an operator's
daily departures. To provide connecting passengers with an equal chance
of being selected in the survey, an operator should conduct its survey
within the secure area of the airport. An operator should select
locations to conduct its survey that would provide a sample that is
random and representative of its operations. For example, an operator
should not conduct a survey at a gate used by shuttle operations unless
the operator is conducting a survey specific to that route or the
operator only conducts shuttle operations.
b. Weighing passengers. An operator that chooses to weigh
passengers as part of a survey should take care to protect the privacy
of passengers. The scale
[[Page 51520]]
readout should remain hidden from public view. An operator should
ensure that any passenger weight data collected remains confidential.
c. Weighing bags. When weighing bags on a particular flight, an
operator should take care to ensure that it is properly accounting for
all items taken aboard the aircraft.
d. Rounding sample results. If the operator uses rounding in the
weight and balance calculations, it is recommended that the operator
round passenger weights to the nearest pound and bag weights to the
nearest half-pound. An operator should ensure that rounding is done
consistently in all calculations.
e. Surveys for particular routes. An operator may conduct a survey
for a particular route if the operator believes that the average
weights on that route may differ from those in the rest of its
operations. To establish a standard average passenger weight along the
route, an operator may survey passengers at only one location. However,
an operator should conduct surveys of personal items and bags at the
departure and arrival locations, unless the operator can verify there
is no significant difference in the weight and number of bags in either
direction along the route.
315. What information might an operator gain from conducting a count
survey?
a. An operator may conduct a survey to count certain items without
determining the weight of those items. For example, an operator may
determine that the standard average weights for male and female
passengers are appropriate for its operations, but on some routes the
passengers are predominantly male or female. In this case, an operator
may conduct a survey to determine the percentage of male and female
passengers. The operator could use the results of the survey to justify
a weight other than the standard weights, which assume a 50-percent
male and 50-percent female mix of passengers. Similarly, an operator
may conduct a survey to determine the number of personal items and
carry-on bags passengers carry aboard aircraft to determine if the
allowance of 16 pounds per passenger is appropriate to its operations.
b. For example, an operator conducts a survey on a particular route
(or multiple routes if amending the program average weight) to count
the percentage of passengers carrying personal items and carry-on bags.
The operator finds that--
(1) Fifty percent of passengers carry one carry-on bag and one
personal item.
(2) Thirty percent of passengers carry one carry-on bag or one
personal item.
(3) Twenty percent of passengers carry neither a carry-on bag nor a
personal item.
(4) The survey results show that the average passenger carries
approximately 21 pounds of personal items and carry-on bags rather than
the standard allowance of 16 pounds. In such a case, it would be
irresponsible for the operator to fail to increase the standard average
weights for that route(s) by 5 pounds per passenger.
Note: The calculation below determines the appropriate allowance
for personal items and carry-on bags.
0.50 `` (16 pounds + 16 pounds)] + [0.30 `` (16 pounds)] + [0.20 ``(0
pounds)] = 20.8 pounds
316. When should an operator conduct another survey to revalidate the
data from an earlier survey?
In order to use survey-derived average weights, an operator must
revalidate such survey data every 36 calendar-months or revert to the
standard average weights, provided the new survey average weight
results are within 2 percent of the standard average weights listed in
this AC.
Section 4. Segmented Passenger Weights
317. What should an operator consider when using segmented weights?
a. The concept of segmented weights involves adding a portion of
the standard deviation to an average weight to increase the confidence
that the actual weight will not exceed the average weight. Like the
standard average weights in Section 2, the segmented weights in Table
3-5 were derived from average weights and standard deviations found
based on NHANES data, assuming a 95-percent confidence interval and 1-
percent tolerable error.
[GRAPHIC] [TIFF OMITTED] TN19AU04.007
[[Page 51521]]
b. An operator may make the following adjustments to the table
above:
(1) An operator may subtract 6 pounds from the passenger weight
outlined above if it has a no-carry-on bag program or does not allow
any carry-on baggage into the cabin of the aircraft.
(2) An operator should add 5 pounds to the weights above during the
winter season.
c. An operator may interpolate between columns on the chart if the
operator's assumed ratio of male passengers to female passengers does
not exactly match the values given.
d. To account for a child's weight, for children ages 2 years to
less than 13 years of age, the standard average child weight located in
Table 3-1 may be used. Weights of children under the age of 2 have been
factored into the segmented adult passenger weight.
318. How are loading envelope curtailment and bag weight affected by an
operator's use of segmented weights?
a. Loading envelope curtailment. An operator using segmented
passenger weights should consider curtailing its operational loading
envelope using the methods described in Appendix 4.
b. Bag weights. An operator using segmented weights may use actual
weights for bags or the standard average bag weights provided in
Section 2. An operator using segmented passenger weights may not use
survey-derived average bag weights.
319. What might be an example of an operator using the segmented
weights in Table 3-5?
An operator of a 30 passenger-seat aircraft conducts a survey to
count the percentage of male and female passengers on its flights and
determines that 50 percent of its passengers are male and 50 percent
are female. If the operator has an approved carry-on bag program, the
operator should use 204 pounds in the summer and 209 pounds in the
winter. If the operator has a no-carry-on bag program, the operator
should use 198 pounds in the summer and 203 pounds in the winter and
account for all plane-side loaded bags as 20 pounds each.
Section 5. Actual Weight Programs
320. If the operator decides to use an actual weights program, how
might it determine the actual weight of passengers?
An operator may determine the actual weight of passengers by--
a. Weighing each passenger on a scale before boarding the aircraft
(types of weight scales and scale tolerances will be defined in the
operator's approved weight and balance control program); or
b. Asking each passenger his or her weight. An operator should add
to this asked (volunteered) weight at least 10 pounds to account for
clothing. An operator may increase this allowance for clothing on
certain routes or during certain seasons, if appropriate.
Note: If an operator believes that the weight volunteered by a
passenger is understated, the operator should make a reasonable
estimate of the passenger's actual weight and add 10 pounds.
321. If the operator decides to use an actual weight program, how
should it determine the actual weights of personal items and bags?
To determine the actual weight of a personal item, carry-on bag,
checked bag, plane-side loaded bag, or a heavy bag, an operator should
weigh the item on a scale.
322. What approach should an operator use to record actual weights?
An operator using actual weights should record all weights used in
the load buildup.
Chapter 4. Operator Reporting Systems and FAA Oversight
Section 1. Pilot and Agent Reporting Systems
400. What are the pilots' and operators' responsibilities in reporting
aircraft loading and manifest preparation discrepancies?
Each operator should develop a reporting system and encourage
employees to report any discrepancies in aircraft loading or manifest
preparation. These discrepancies may include errors in documentation or
calculation, or issues with aircraft performance and handling qualities
that indicate the aircraft weight or balance is not accurate. Operators
should attempt to determine the cause of each discrepancy and take
appropriate corrective action. This would include a load audit on
affected flights or conducting a passenger or bag weight survey in
accordance with this AC if trends indicate it is warranted.
Section 2. FAA Oversight
401. Which FAA inspectors are responsible for overseeing an operator's
weight and balance program?
The FAA has divided the responsibility of overseeing an operator's
weight and balance control program between the operator's principal
operations inspector (POI) and principal maintenance inspector (PMI).
An operator that wishes to change aspects of its weight and balance
control program, including average weights, should submit all
applicable supporting data to the POI and PMI, as applicable, for
approval. If the FAA approves the changes, the FAA will issue revised
OpSpecs, MSpecs, or LOA, as appropriate.
402. Which portions of OpSpecs or MSpecs are relevant to an operator's
weight and balance program?
a. This AC details methods to develop a weight and balance control
program with greater accuracy and increased flexibility. By changing
its OpSpecs or MSpecs, an operator may alter the weights used in its
weight and balance control program to include appropriate combinations
of standard average weights, average weights based on survey results,
or actual weights.
b. Parts A and E of OpSpecs or MSpecs authorize an operator's
weight and balance control program. These parts will address--
(1) Average passenger and bag weights;
(2) Situations when the use of average weights is inappropriate;
(3) The treatment of charter flights or special groups, if
applicable;
(4) The type of loading schedule and instructions for its use;
(5) Aircraft weighing schedules; and
(6) Other procedures that the operator may require to assure
control of weight and balance.
c. Paragraph E096 of the OpSpecs or MSpecs is issued to an operator
with an approved aircraft fleet actual or average weight program. The
FAA issues this paragraph after reviewing and approving an operator's
weight and balance control program in its entirety.
d. Paragraph A011 of the OpSpecs or MSpecs is issued to an operator
with an approved carry-on bag program. This paragraph provides details
about the operator's approved carry-on bag program and states whether
the operator has a carry-on bag program or a no-carry-on bag program.
The FAA will issue this paragraph after reviewing the operator's carry-
on baggage program in its entirety.
e. If an operator chooses to use standard average weights as
outlined in this AC, the FAA will document that decision by issuing one
or more of the following OpSpecs or MSpecs paragraphs. If an operator
proposes to use different average weights (weights other than the
standard average or segmented weights) and the FAA concurs with the
statistically valid data provided by the operator to support
[[Page 51522]]
such average weight differences, then those differences will be
documented in the following OpSpecs or MSpecs. Although these
paragraphs authorize an operator to use average and/or segmented
weights, an operator may use actual weights at any time once issued
these paragraphs.
(1) Paragraph A097--Small Cabin Aircraft Passenger and Baggage
Weight Program.
(2) Paragraph A098--Medium Cabin Aircraft Passenger and Baggage
Weight Program.
(3) Paragraph A099--Large Cabin Aircraft Passenger and Baggage
Weight Program.
Note: If an operator does not provide the FAA with adequate
information to justify the issuance of one of the above paragraphs
that documents the use of standard average, survey-derived average,
and/or segmented weights, the FAA may issue paragraph A096,
requiring the operator to use actual weights for a specific aircraft
or aircraft fleet.
f. If an operator chooses to develop a weight and balance control
program using only actual weights for all the aircraft it operates, the
FAA may issue OpSpec/MSpec paragraph A096. The FAA will not issue
paragraphs A097, A098, or A099 to operators with a weight and balance
control program that uses only actual weights. The FAA will only issue
paragraphs A096, A097, A098, and/or A099 after reviewing the operator's
actual or average weight program.
g. An operator that receives approval to use nonstandard average
weights should document and make available, upon request, the data and
methodology used to derive those weights. An operator's documentation
should be sufficiently comprehensive to allow the FAA to reproduce the
same results during an audit. An operator should retain this
documentation for as long as the operator uses the nonstandard average
weights in its weight and balance control program.
h. If an operator chooses to conduct a survey, the operator will
use the results of the survey to establish a revised average weight and
must curtail the loading envelope as necessary. However, if the survey
results indicate the average weights are within 2 percent of the
standard average weights outlined in this AC, the operator may elect to
adopt the standard average weights only after submitting the survey
results to the FAA and receiving approval through its OpSpecs, MSpecs,
or LOA.
i. For operators using an onboard weight and balance system to
determine the weight and balance of the aircraft, the FAA will issue
OpSpecs or MSpecs paragraph A096. Paragraph A096 documents the use of
actual weights and the use of its onboard weight and balance system.
For an operator that chooses to use standard average weights as a
backup system, the FAA will issue paragraphs A097, A098, or A099, as
appropriate. By authorizing the use of average weights, the operator
may elect to use actual weights derived from its onboard weight and
balance system, and may use average weights as an alternative should
the system be inoperative.
j. For operators of all-cargo aircraft, the FAA will issue OpSpecs
or MSpecs paragraph A096. Paragraph A096 documents the use of actual
weights, with the exception of flightcrew and flightcrew bag weights.
These weights may be accounted for using the standard average weights
described in Chapter 3, Table 3-3.
403. When will the FAA revise the standard average weights in this AC?
The FAA will periodically review the standard average passenger
weights listed in this AC, after the release of a new NHANES. If the
FAA finds that the data from NHANES indicates a weight change of more
than 2 percent, the FAA will revise this AC to update the standard
average weights.
James J. Ballough,
Director, Flight Standards Service.
Appendix 1. Definitions
1. Basic empty weight. The aircraft empty weight, adjusted for
variations in standard items.
2. Cargo. As used in this advisory circular (AC), cargo refers
to everything carried in the cargo compartments of the aircraft.
This includes bags, mail, freight, express, and company material. It
also includes live animals, dangerous goods, and hazardous materials
as subcategories of the above.
3. Carry-on bag. A bag that the operator allows the passenger to
carry onboard. It should be of a size and shape that will allow it
to be stowed under the passenger seat or in a storage compartment.
The operator establishes the exact dimensional limits based on the
particular aircraft stowage limits.
4. Certificated weight and CG limits. Weight and center of
gravity (CG) limits are established at the time of aircraft
certification. They are specified in the applicable aircraft flight
manual (AFM).
5. Checked bags. Checked bags are those bags placed in the cargo
compartment of the aircraft. This includes bags that are too large
to be placed in the cabin of the aircraft or those bags that are
required to be carried in the cargo compartment by regulation,
security program, or company policy. For bags checked plane-side,
see the definition for plane-side loaded bags.
6. Curtailment. Creating an operational loading envelope that is
more restrictive than the manufacturers' CG envelope, to assure the
aircraft will be operated within limits during all phases of flight.
Curtailment typically accounts for, but is not limited to, in-flight
movement, gear and flap movement, cargo variation, fuel density,
fuel burn-off, and seating variation.
7. Fleet empty weight. Average operational empty weight (OEW)
used for a fleet or group of aircraft of the same model and
configuration.
8. Freight. Cargo carried for hire in the cargo compartment that
is not mail or passenger bags.
9. Heavy bags. For this AC, heavy bags are considered any bag
that weighs more than 50 pounds but less than 100 pounds. Bags that
are 100 pounds or more are considered freight.
10. Large cabin aircraft. Aircraft with a maximum type-
certificated seating capacity of 71 or more passenger seats.
11. Loading envelope. Weight and CG envelope used in a loading
schedule. Loading the aircraft within the loading envelope will
maintain the aircraft weight and CG within the manufacturer's type-
certificated limits throughout the flight.
12. Loading schedule. Method for calculating and documenting
aircraft weight and balance prior to taxiing, to ensure the aircraft
will remain within all required weight and balance limitations
throughout the flight.
13. Manufacturer's empty weight. Weight of structure,
powerplant, furnishings, systems, and other items of equipment that
are an integral part of a particular aircraft configuration. (It is
essentially a ``dry'' weight, including only those fluids contained
in closed systems.)
14. Maximum landing weight. The maximum weight at which the
aircraft may normally be landed.
15. Maximum takeoff weight. The maximum allowable aircraft
weight at the start of the takeoff run.
16. Maximum taxi weight. The maximum allowable aircraft weight
for taxiing.
17. Maximum zero-fuel weight. The maximum permissible weight of
an aircraft with no disposable fuel and oil.
18. Medium cabin aircraft. Aircraft with a maximum type-
certificated seating capacity between 70 and 30 passenger seats,
inclusive.
19. Moment. A force that causes or tries to cause an object to
rotate.
20. Onboard weight and balance system. A system that weighs an
aircraft and payload, then computes the CG using equipment onboard
the aircraft.
21. Operational empty weight (OEW). Basic empty weight or fleet
empty weight plus operational items.
22. Operational items. Personnel, equipment, and supplies
necessary for a particular operation but not included in basic empty
weight. These items may vary for a particular aircraft and may
include, but are not limited to, the following:
a. Crewmembers, supernumeraries, and bags;
b. Manuals and navigation equipment;
c. Passenger service equipment, including pillows, blankets, and
magazines;
d. Removable service equipment for cabin, galley, and bar;
[[Page 51523]]
e. Food and beverage, including liquor;
f. Usable fluids, other than those in useful load;
g. Required emergency equipment for all flights;
h. Life rafts, life vests, and emergency transmitters;
i. Aircraft unit load devices;
j. Potable water;
k. Drainable unusable fuel;
l. Spare parts normally carried aboard and not accounted for as
cargo; and
m. All other equipment considered standard by the operator.
23. Passenger assist/comfort animals and devices. These include,
but are not limited to, canes, crutches, walkers, wheelchairs,
medically-required animal comfort companions, or animals required to
assist the vision impaired.
24. Passenger weight. Passenger weight is the actual weight or
the approved average weight of the passenger.
a. An adult is defined as an individual 13 years or older.
b. A child is defined as an individual aged 2 to less than 13
years of age.
c. Infants are children who have not yet reached their second
birthday and are considered part of the adult standard average and
segmented passenger weight.
25. Personal item. Items the operator may allow a passenger to
carry aboard, in addition to a carry-on bag. Typically, an operator
may allow one personal item such as a purse, briefcase, computer and
case, camera and case, diaper bag, or an item of similar size. Other
items, such as coats, umbrellas, reading material, food for
immediate consumption, infant restraining device, and passenger
assist/comfort animals and devices, are allowed to be carried on the
aircraft and are not counted against the personal item allowance.
26. Plane-side loaded bag. Any bag or item that is placed at the
door or steps of an aircraft and subsequently placed in the aircraft
cargo compartment or cargo bin.
27. Reference Balance Arm (BA). The horizontal distance from the
reference datum to the CG of an item.
28. Segmented Weights. Passenger weights derived by adding a
portion of the standard deviation to an average weight to increase
the confidence that the actual weight will not exceed the average
weight.
29. Small cabin aircraft. Aircraft with a maximum type-
certificated seating capacity between 5 and 29 passenger seats,
inclusive.
30. Standard basic empty weight. Manufacturer's empty weight
plus standard items.
31. Standard items. Equipment and fluids not considered an
integral part of a particular aircraft and not a variation for the
same type of aircraft. These items may include, but are not limited
to, the following:
a. Unusable fuel and other unusable fluids;
b. Engine oil;
c. Toilet fluid and chemical;
d. Fire extinguishers, pyrotechnics, and emergency oxygen
equipment;
e. Structure in galley, buffet, and bar; and
f. Supplementary electronic equipment.
32. Useful Load. Difference between takeoff weight and OEW. It
includes payload, usable fuel, and other usable fluids not included
as operational items.
Appendix 2. Source of Standard Average Weights in This AC
1. Standard average passenger weights.
a. The Federal Aviation Administration (FAA) examined data from
several large-scale, national health studies conducted by U.S.
Government health agencies. The FAA found that the National Health
and Nutrition Examination Survey (NHANES), conducted by the Centers
for Disease Control (CDC), provided the most comprehensive and
appropriate data. The data in NHANES cover a broad spectrum of the
general population, are based on a large sample size, and are not
restricted geographically to a particular area.
b. The CDC collects NHANES data annually by conducting an actual
scale weighing of approximately 9,000 subjects in a clinical
setting. The standard deviation of the sample was 47 pounds. The CDC
last published results from NHANES in 2000. Additional information
on NHANES can be found at the following Web sites:
(1) General information. http://www.cdc.gov/nchs/nhanes.htm.
(2) Analytic and reporting guidelines. http://www.cdc.gov/nchs/data/nhanes/nhanes3/nh3gui.pdf.
(3) Data files for 1999-2000 survey. http://www.cdc.gov/nchs/about/major/nhanes/NHANES99_00.htm.
c. The FAA used most recent NHANES data set from surveys
conducted in 1999 and 2000 to calculate the standard average
passenger weights used in this advisory circular (AC). From this
data set, the FAA separated out a separate data set of individuals
who had not yet reached their 13th birthday to determine average
child weight. From the remaining adult data set, the FAA removed all
weight data that indicated the subject was clothed during the
weighing and removed all data points more than two standard
deviations from the mean. The FAA then calculated the average
weights for males and females in the remaining data set.
2. Standard average bag weights.
To determine standard average weights for different types of
bags, the FAA closely examined previous surveys conducted by
operators, including several surveys conducted in response to FAA
Notice 8400.40, Weight and Balance Control Programs for 10 to 19
Seat Airplanes Operated Under 14 CFR 121. The results of those
surveys are summarized in Table 2-1.
[GRAPHIC] [TIFF OMITTED] TN19AU04.008
Appendix 3. Sample Operational Loading Envelope
1. Introduction.
The following is an example of how to develop an operational
loading envelope. For this example, a hypothetical 19-seat commuter
category aircraft is used. Although this example uses inches to
measure fuselage station, an operator may choose to use an index
system for convenience.
2. Assumptions for this example.
a. Passenger weight. Because the aircraft is certificated under
the commuter category of Title 14 of the Code of Federal Regulations
(14 CFR) part 23 and because it is originally type-certificated for
5 or more passenger seats, it would be appropriate to use the
average weights listed in Chapter 3, Section 2. For this example, it
is assumed that the operator does not have a carry-on bag program.
Therefore, the operator should use a standard average passenger
weight of 189 pounds in winter and 184 pounds in summer. For this
example, a standard average passenger weight of 189 pounds is used.
The operator also assumes that passengers are distributed throughout
the cabin in accordance with the window-aisle-remaining method. Note
that because this aircraft has only two window seats per row, the
operator may reasonably assume that passengers begin seating
themselves in the front of the cabin and select the most forward
seat available.
b. Bag weights. For this example, the operator assumes that a
checked bag weighs 30 pounds and a plane-side loaded bag weighs 20
pounds.
c. Interior seating. For this example, consider a commuter
category 19-seat aircraft with the interior seating diagram shown in
Figure 3-1.
[[Page 51524]]
[GRAPHIC] [TIFF OMITTED] TN19AU04.009
3. Curtailments for passenger seating variation.
a. Establishing zones. The operator elects to separate the
passenger cabin into three zones. Zone 1 will contain rows 1 to 3,
zone 2 will contain rows 4 to 6, and zone 3 will contain rows 7 to
9.
b. Determining the centroid of each zone. When using cabin
zones, an operator assumes that all passengers are sitting at the
centroid of their zone. To find the centroid of each zone--
(1) Multiply the number of seats in each row of the zone by the
location of the row,
(2) Add each number calculated in step 1, and
(3) Divide the number in step 2 by the total number of seats in
the zone.
Note: For this sample aircraft, see Tables 3-1 through 3-3
below.
[[Page 51525]]
[GRAPHIC] [TIFF OMITTED] TN19AU04.010
c. Comparing loading assumptions. To determine the appropriate
amount of curtailment, the operator should compare aircraft loading
based on the window-aisle-remaining assumption with aircraft loaded
based on the assumption that passengers are sitting at the centroid
of their respective zones. An operator may determine the appropriate
curtailment by comparing the moments resulting from these
assumptions and identifying the loading scenarios that result in the
most forward or aft center of gravity (CG) location. See Tables 3-4
through 3-12 below.
[[Page 51526]]
(1) Curtailment calculation for zone 1.
[GRAPHIC] [TIFF OMITTED] TN19AU04.011
[[Page 51527]]
(2) Curtailment calculation for zone 2.
[GRAPHIC] [TIFF OMITTED] TN19AU04.012
[[Page 51528]]
(3) Curtailment calculation for zone 3.
[GRAPHIC] [TIFF OMITTED] TN19AU04.013
(4) Determining the most adverse loading. It is important that
an operator examine the above results for each zone and determine
which loading scenario results in the greatest difference in
moments. For zones 1 and 2, having two, three, or four passengers in
the zone results in the largest difference between the moments. For
zone 3, having four passengers in the zone results in the largest
difference. In this case, the operator should curtail the
manufacturer's loading envelope forward and aft by the sum of these
moments, 36,666 inch-pounds, to account for the potential variation
in passenger seating. In this example, the 36,666 inch-pounds is the
sum of 11,340 from Table 3-6; 10,962 from Table 3-9; and 14,364 from
Table 3-12.
(5) Using actual seating location. Alternatively, an operator
may reasonably avoid the above curtailment calculations by
determining the actual seating location of
[[Page 51529]]
each passenger in the cabin. By eliminating potential variation in
passenger seating, an operator would not need to make assumptions
about passenger seating and would not need to curtail the loading
envelope accordingly. An operator choosing to use actual seating
location should have procedures in place to ensure that passengers
sit in their assigned location.
4. Other curtailments to the manufacturer's loading envelope.
a. Variation in passenger weight. Because the operator in this
example elects to use standard average weights on a small-cabin
aircraft, an additional curtailment for potential variation in
passenger weight is required. The operator should curtail the
manufacturer's loading envelope by 23,791 inch-pounds forward and
aft to account for the variation in passenger weight. A full
explanation of this calculation is contained in Appendix 4.
b. Variation in fuel density. Because the loading of fuel does
not significantly change the CG of the aircraft, the operator would
not need to provide a curtailment for variation in fuel density.
c. Fuel movement in flight. For this sample aircraft, the
manufacturer has considered the movement of fuel in flight.
Therefore, the operator does not need to include additional
curtailments in the operational loading envelope.
d. Fluids. The sample aircraft does not have a lavatory or
catering.
e. Bags and freight. The sample aircraft has an aft bag
compartment split into two sections. If the operator has procedures
in place to restrict the movement of bags between the two sections,
no additional curtailment to the envelope is required.
f. In-flight movement of passengers and crewmembers. Because
there are no flight attendants and the aircraft is not equipped with
a lavatory, it is reasonable to assume that passengers or
crewmembers will not move about the cabin in flight.
g. Movement of flaps and landing gear. The manufacturer of the
sample aircraft has considered the movement of flaps and landing
gear in the development of its loading envelope. The operator does
not need to include any additional curtailments in its operational
loading envelope for the movement of those items.
h. Fuel consumption. To ensure the sample aircraft remains
within the manufacturer's CG limits as fuel is consumed, the
operator should curtail the aft CG at weights less than the zero-
fuel weight by 8,900 inch-pounds. In this example, the 8,900 inch-
pounds is the fuel burn deviation that would bring the aircraft
outside the aft CG limit during the course of flight.
5. Operational loading envelope diagrams.
a. Figure 3-2 below shows the operator's curtailments to the
manufacturer's loading envelope, based on the assumptions made about
variations in passenger seating and weight, as well as fuel
consumption.
[GRAPHIC] [TIFF OMITTED] TN19AU04.014
b. To expand the operational loading envelope, an operator could
choose to use the actual seating location of passengers in the cabin
and eliminate the curtailment for variations in passenger seating.
Figure 3-3 below shows the expansion of the operational loading
envelope.
[[Page 51530]]
[GRAPHIC] [TIFF OMITTED] TN19AU04.015
Appendix 4. Additional Curtailments to CG Envelopes To Account for
Variations to Passenger Weights
a. The use of average weights for small cabin aircraft requires
consideration of an additional curtailment to the center of gravity
(CG) envelope for passenger weight variations and male/female
passenger ratio. This curtailment is in addition to the standard
curtailments discussed in Chapter 2.
(1) Passenger weight variation is determined by multiplying the
standard deviation (from the source of the average passenger weight
used) by the row factor from Table 4-1. The following table ensures
a 95-percent confidence level of passenger weight variation, using
the window-aisle-remaining seating method.
[[Page 51531]]
[GRAPHIC] [TIFF OMITTED] TN19AU04.016
(2) Protect against the possibility of an all-male flight by
subtracting the difference between the male and average passenger
weight.
(3) The sum of these two provides an additional weight to be
used for CG curtailment, similar to the way in which passenger
seating variation is calculated.
b. If the operator chooses to use the passenger cabin zone
concept (as described in Appendix 3) and apply this concept to
account for variation in passenger weight, then the row factor in
Table 4-1 corresponding to the number of rows in each zone should be
used. For the purposes of this curtailment, the zone can be no
smaller than two rows, if row count is used for passenger seating
calculations. Therefore, if an operator chooses to use row count,
the operator must use the row factor for two rows.
c. Calculation of the curtailment passenger weight variation is
decided by multiplying the standard deviation by the correction
factor and adding the difference between male and female passenger
weight. For example, assuming a 47 pound standard deviation, the
difference between the average passenger weight and an all-male
weight is 10 pounds (from 1999-2000 National Health and Nutrition
Examination Survey (NHANES) data), and a sample aircraft with 9 rows
in a 2-abreast configuration. The additional weight to be curtailed
is determined as:
Weight for Additional Curtailment = (47 x 1.70) + (10) = 90 lbs
d. For the example, the additional curtailment should be
accomplished by assuming passenger loading at 90 pounds using the
program method for passenger seating variation (e.g., window-aisle-
remaining). Using the window-aisle-remaining method, the additional
curtailment in the example is determined to be 62,310 inch-pounds
forward and aft. Table 4-2 displays the calculations used in this
example.
Note: The following definitions describe the parameters used in
the sample:
Seat Centroid: Location of passenger weight at seat.
Seat Moment: Additional passenger weight x seat
centroid.
Total Weight: Sum of additional passenger weights
(running total).
Total Moment: Sum of additional passenger moments.
Moment Deviation: Difference between total moment and
moment generated by assuming additional passenger weight is located
at the cabin centroid (323.8 in).
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Appendix 5. Options To Improve Accuracy
A number of options are available that enable operators to
deviate from standard assumed weights and may also provide relief
from constraints required when assumed averages are used. These
options include:
(1) Surveys. Surveys may be accomplished for passenger weights
(to include carry-on bags), checked baggage weights, male/female
ratios and fuel densities. These surveys may be conducted for entire
operator route systems, or by specific market or region. Surveys
practices and data reduction must conform to the requirements
defined in this advisory circular (AC). Use of surveys may allow an
operator to use passenger and baggage weights less than the standard
specified in this AC. Also, a survey may find that the assumed male/
female ratio is incorrect and appropriate adjustments must be made.
For example, let's assume the following results from an approved
passenger and baggage survey.
Male passenger weight (M) = 183.3 pounds
Female passenger weight (F) = 135.8 pounds
Difference between male and average passenger weights = 24.0 pounds
Standard deviation of total sample (Sigma) = 47.6 pounds
Male/female ratio (Pax Ratio) = 50.6 percent
Checked baggage weight = 29.2 pounds
Baggage checked plane-side = 21.3 pounds
Carry-on and personal items weight (CO Wt) = 10.4 pounds
Carry-on and personal items per passenger ratio (CO Ratio) = 0.82
pounds
Survey conducted in summer months
The resulting assumed passenger weight for loading is expressed
as:
Passenger Weight = M x Pax Ratio + F x (1 - Pax Ratio) + CO Wt x CO
Ratio
And is determined as:
Summer Passenger Weight = 0.506 x 183.3 + (1 - 0.506) x 135.8 + 10.4
x 0.82 = 169 lb
Winter Passenger Weight = 169 + 5 = 174 lb
Survey results would also be used to determine the additional
curtailment for variations to passenger weight. Assuming a 19-seat
aircraft in 2-abreast configuration in our example, the additional
weight to be curtailed would be:
Additional Weight for Curtailment = (47.6 x 1.70) + 24 = 104.9 lb
Also in our example, the assumed checked baggage weight is 30
pounds. Plane-side loaded bags would be assumed to weigh 20 pounds.
(These weights are the standard average weights provided for a no-
carry-on baggage program as described in Chapter 3, Section 2).
(2) Actual Weights. It is permissible to use actual weights in
lieu of standard average, segmented, or survey-derived average
weights (if applicable). Parameters that may use actual weights
include passenger weights, checked baggage weights, carry-on bag
weights, crew weights, and fuel density/weight.
(3) Passenger Cabin Zones and Row Count. Passenger cabins may be
split up into zones provided an acceptable procedure for
determination of passenger seating is included (e.g., use of seat
assignments or crew counts seated passengers by zone). If zones are
used, it may be reasonable for the operator to reduce the center of
gravity (CG) passenger seating curtailment suggested in this AC by
accommodating variations within each individual zone separately and
totaling the results. Passenger row count allows the operator to
eliminate the seating variation by accounting for where the
passenger is actually seated.
An example of use of passenger zones follows.
Assume an aircraft interior as displayed in Figure 5-1.
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Assume that for weight and balance purposes, it is desirable to
break the cabin up into three passenger zones. The passenger zones
will be determined as zone 1 (rows 1-3), zone 2 (rows 4-6), and zone
3 (rows 7-9). Use of the window-aisle-remaining method will be used
in each zone to provide a total curtailment to the CG envelope. (For
this sample aircraft, window-aisle-remaining method simply becomes
forward and aft end loading). For each zone, a zone centroid must be
calculated by counting the total number of seats and averaging their
location.
Zone 1 centroid = (2 x 198.0 + 2 x 228.0 + 2 x 258.0) / (2 + 2 + 2)
= 228.0 in.
Zone 2 centroid = (2 x 289.0 + 2 x 318.0 + 2 x 347.0) / (2 + 2 + 2)
= 318.0 in.
Zone 3 centroid = (2 x 377.0 + 2 x 407.0 + 3 x 436.0) / (2 + 2 + 3)
= 410.9 in.
Assuming the standard winter passenger weight of 195 pounds is
used for the curtailment, the calculation of total moment is
required for comparison to moment assuming each passenger is seated
at the centroid of each passenger zone. The total moment is found by
summing the individual moments calculated at each occupied seat in
the window-aisle-remaining progression.
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The curtailment for passenger seating variation is determined by
adding the largest delta moments from each of the passenger zones.
In our example, the curtailment to the forward CG limit for
passenger seating variation is -37,719 inch-pounds (-11,700 + -
11,310 + - 4,709). Similarly, curtailment to the aft limit of the CG
envelope using window-aisle-remaining method loading from the most
aft seat row moving forward (in each zone) would result in an
adjustment of 37,719 inch-pounds. Figures 5-2 through 5-4
graphically show the curtailments for each passenger zone through
use of forward and aft end loading using our example.
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(4) Actual M/F Counts. Loading systems may use separate male and
female assumed passenger weights for each operation. If the
operator's weight and balance program is approved for use of male/
female weights, then the operator must count the number of male
passengers and female passengers separately. The male and female
weights used may be from the development of standard passenger
weight as described in this AC or they may be determined through an
operator-developed survey as also described in this AC. Use of male/
female weights may be for entire operations or for a particular
route and/or region of flying.
An example of how male/female ratios can be applied to weight
and balance systems follows.
Assuming the operator is using the survey results as described
in subparagraph (1) above, the assumed male and female passenger
weights, including average carry-on baggage, are computed as:
Male passenger weight (summer) = 183.3 + 10.4 x 0.82 = 192 lb
Male passenger weight (winter) = 192 + 5 = 197 lb
Female passenger weight (summer) = 135.8 + 10.4 x 0.82 = 144 lb
Female passenger weight (winter) = 144 + 5 = 149 lb
The weight and balance manifest would provide for identification of
male/female identification and the passenger weights would be summed
accordingly. For instance, 7 male and 11 female passengers would
result in a total passenger weight of (7 x 192) + (11 x 144) = 2,928
pounds.
(5) Adolescent (Child) Weights. In most circumstances, an
operator may consider any passenger less than 13 years of age, who
is occupying a seat, to weigh less than an adult passenger as
described in this AC. The standard adolescent child weights can be
found in Table 3-1 of Chapter 3.
(6) Standard Weights With Approved No-Carry-on Baggage Program.
Summer Passenger Weight = 184 lb
Winter Passenger Weight = 189 lb
Checked Baggage Weight = 30 lb each
Baggage Checked Plane-side = 20 lb each
Inclusion in the no-carry-on baggage program does not preclude use
of actual or surveyed weights for passengers, carry-on/personal
items, checked baggage, or baggage checked plane-side.
(7) Automation. Automation may also be used to provide a more
accurate weight and balance program. Examples of automation include
use of seat assignments for the determination of passenger moment
and historical seating to determine passenger moment.
Appendix 6. Sample CG Envelope Development
Outlined below is an example of the development of a center of
gravity (CG) envelope construction for a 19-seat commuter category
aircraft. The sample system uses a CG diagram displayed in inches.
Operators' systems may use a variety of methods to display CG
diagram, including an Index system detailed in Chapter 2, Section 2
and in Appendix 3.
Sample Development of Weight and Balance System for 19-Seat Aircraft
a. CG Envelope Construction. The certified CG envelope provided
by the manufacturer must be examined for the following curtailments.
(1) Variations to Passenger Seating (Outlined in Chapter 2). In
this example, the window-aisle-remaining method was used considering
a passenger weight of 189 pounds and using 3 passenger zones, where
zone 1 is defined as rows 1-3, zone 2 is defined as rows 4-6, and
zone 3 is defined as rows 7-9. (189 lb/pax is used since the
operator will be using a no-carry-on baggage program as detailed
later on in this sample exercise). The resulting curtailment for use
of 3 passenger zones is 36,600 inch-pounds forward and aft.
(2) Variations to Passenger Weight (Outlined in Appendix 4).
Since the sample
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aircraft falls into the group of aircraft requiring full evaluation
of small cabin aircraft rules, application of a curtailment due to
variations to passenger weight is required.
(a) Use of Passenger Zone Concept for Curtailment. Considering
three cabin zones with each zone containing three rows in a 2-
abreast configuration, the required row factor (see Appendix 4,
Table 4-1) is 2.41. The row factor is multiplied by the standard
deviation and the difference between average male and average female
weights is added to provide the additional weight consideration. In
our example, the standard deviation is calculated from the National
Health and Nutrition Examination Survey (NHANES) data as 47 pounds,
and the difference between average all-male and average passenger
weights is 10 pounds. The resulting additional weight for
curtailment is 47 x 2.41 + 10 = 123 pounds. This additional weight
is applied per the window-aisle-remaining concept for each cabin
zone independently and the results are summed to determine the
amount of curtailment. In this case, the curtailment is found to be
23,791 inch-pounds forward and aft.
(b) Use of Row Count for Curtailment. When using row count, the
required row factor is 2.96. The row factor is multiplied by the
standard deviation and the difference between average male and
average female weights is added to provide the additional weight
consideration. In our example, the standard deviation is calculated
from the NHANES data as 47 pounds, and the difference between
average all-male and average passenger weights is 10 pounds. The
resulting additional weight for curtailment is 47 x 2.96 + 10 = 149
pounds. This additional weight is applied as if a 2-row passenger
zone concept is used for passenger seating. The resulting
curtailment is determined to be 16,657 inch-pounds forward and aft.
(3) Variations to Fuel Density. Since the loading of fuel does
not significantly shift the CG for the aircraft, it is not necessary
to correct for variations in fuel density (i.e., the correction is
negligible).
(4) Fuel Movement in Flight. Fuel movement has been considered
by the manufacturer in the development of the certified envelope,
making an additional curtailment unnecessary.
(5) Fluids. The sample aircraft does not have a lavatory and
there is no catering.
(6) Baggage and Freight. The sample aircraft provides a baggage
web in the aft baggage compartment, splitting the compartment into
forward and aft sections. In our example, we assume the operator is
making full use of this web and the movement of baggage is
restricted. No curtailment is necessary.
(7) In Flight Movement of Passengers and Crew. Since there are
no flight attendants and no lavatories on the sample aircraft, it is
reasonable to assume that the passengers will remain in their seats
for the duration of the flight. Therefore, it is not necessary to
curtail the limits for passenger and crew in-flight movement.
(8) Movement of Flaps and Landing Gear. In the case of the
sample aircraft, the manufacturer has included consideration of flap
and landing gear movement in the development of the certified
envelope. No additional curtailment is necessary.
(9) Fuel consumption. The fuel vector for the sample aircraft
provides a small aft movement that requires a -8,900 inch-pounds
curtailment to the aft zero fuel weight limits to ensure the
aircraft does not exceed the aft limit as fuel is burned. This
equates to a -0.8 inch curtailment at an estimated operational empty
weight of 11,000 pounds with a linear transition to a -0.6 inch
curtailment at MZFW of 16,155 pounds. In this example, the 8,900
inch-pounds is the fuel burn deviation that would bring the aircraft
outside the aft CG limit during the course of flight.
b. Three operational curtailments to the sample aircraft CG
envelope are required. These are for variations to passenger seating
and passenger weight, and fuel burn-off. Figure 6-1 displays the
operational CG envelope highlighting the required curtailments.
BILLING CODE 4910-13-P
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c. Assuming the operator wishes to widen the envelope, use of
actual passenger seating (row count) may be used to eliminate the
curtailment required for variations to passenger seating. Figure 6-2
displays a CG envelope that makes use of actual passenger seating.
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d. No-Carry-On Baggage Program. This example assumes a no-carry-
on bag program. This allows consideration of reduced passenger
weight to 184 pounds (summer) and 189 pounds (winter). Carry-on bags
checked at the gate or ``plane-side loaded'' will be counted as 20
pounds/bag. Bags checked at the ticket counter will remain at 30
pounds/bag.
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[FR Doc. 04-18905 Filed 8-18-04; 8:45 am]
BILLING CODE 4910-13-C