[Federal Register Volume 64, Number 136 (Friday, July 16, 1999)]
[Notices]
[Page 38501]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-18023]


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DEPARTMENT OF TRANSPORTATION

Research and Special Programs Administration


Potential Service Interruptions in Supervisory Control and Data 
Acquisition Systems

AGENCY: Research and Special Programs Administration (RSPA), DOT.

ACTION: Notice; issuance of advisory bulletin.

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SUMMARY: RSPA is issuing this advisory bulletin to notify to owners and 
operators operators of natural gas and hazardous liquid pipeline 
systems of to advise them to review the capacity of their Supervisory 
Control and Data Acquisition (SCADA) system to ensure that the system 
has resources to accommodate normal and abnormal operations on its 
pipeline system. In addition, SCADA configuration and operating 
parameters should be periodically reviewed, and adjusted if necessary, 
to assure that the SCADA computers are functioning as intended. 
Further, operators should ensure that system modifications do not 
adversely affect overall performance of the SCADA system. We recommend 
that the operator consult with the original system designer.

ADDRESSES: This document can be viewed on the Office of Pipeline Safety 
(OPS) home page at: http://ops.dot.gov.

FOR FURTHER INFORMATION CONTACT: For further information, contact Chris 
Hoidal, Director, OPS Western Region at 303-231-5701, or by e-mail at 
[email protected].

SUPPLEMENTARY INFORMATION:

I. Background

    During an Office of Pipeline Safety (OPS) investigation of a recent 
pipeline incident, OPS inspectors identified inadequate SCADA 
performance as an operational safety concern. Immediately prior to and 
during the incident, the SCADA system exhibited poor performance that 
inhibited the pipeline controllers from seeing and reacting to the 
development of an abnormal pipeline operation.
    Preliminary review of the SCADA system indicates that the processor 
load (a measure of computer performance utilization) was at 65 to 70 
percent during normal operations. Immediately prior to an upset 
condition occurring on the pipeline, the SCADA encountered an internal 
database error. The system attempted to reconcile the problem at the 
expense of other processing tasks. The database error, coupled with the 
increased data processing burden of the upset condition, hampered 
controller operations. In fact, key operator command functions were 
unable to be processed immediately prior to and during the abnormal 
operation. It is possible that post installation modifications may have 
hampered the system's ability to function appropriately.
    The combination of the database error, the inadequate reserve 
capacity of the SCADA processor, and the unusually dynamic changes that 
occurred during the upset condition, appear to have combined and 
temporarily overburdened the SCADA computer system. This may have 
prevented the pipeline controllers from reacting and controlling the 
upset condition on their pipeline as promptly as would have been 
expected.

II. Advisory Bulletin  (ADB-99-03)

To: Owners and Operators of Hazardous Liquid and Natural Gas Pipelines
Subject: Potential Service Interruptions in Supervisory Control and 
Data Acquisition Systems
Purpose: Inform pipeline system owners and operators of potential 
operational limitations associated with Supervisory Control and Data 
Acquisition (SCADA) systems and the possibility of those problems 
leading to or aggravating pipeline releases.
Advisory: Each pipeline operator should review the capacity of its 
SCADA system to ensure that the system has resources to accommodate 
normal and abnormal operations on its pipeline system. In addition, 
SCADA configuration and operating parameters should be periodically 
reviewed, and adjusted if necessary, to assure that the SCADA computers 
are functioning as intended. Further, operators should assure system 
modifications do not adversely affect overall performance of the SCADA 
system. We recommend that the operator consult with the original system 
designer.
Stacey L. Gerard,
Director, Policy, Regulations and Training.
[FR Doc. 99-18023 Filed 7-15-99; 8:45 am]
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