MN-FLT-OH-201
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VNAV INVALID-PERF Scratchpad Message
GOT-3
Flight Crew Operations Manual Bulletin
for
Gol Linhas Aereas S.A.
Number:
GOT
-
3
IssueDate:
March 15, 2018
Airplane Effectivity: B737-7/8/9 Airplanes with FMC Software U13
Subject:
VNAV INVALID-PERF Scratchpad Message
Reason:
To inform the Flight Crews of an anomaly in which the VNAV
INVALID-PERF scratchpad message cannot be cleared unless an
approach is selected in the active flight plan.
THE FOLLOWING PROCEDURE AND/OR INFORMATION IS EFFECTIVE UPON RECEIPT
Background Information
During a Boeing flight test the following software exception error was
discovered. When certain forecast wind data is entered into the DES FORECAST
page and no approach is selected in the active flight plan, FMC predictions stop,
VNAV disengages, the VNAV INVALID-PERF scratchpad message shows and
the FMC Alert Lights illuminate. This software exception causes the Cost Index
(CI) to be replaced with box prompts on the PERF INIT page. The corrective
action for VNAV INVALID-PERF scratchpad message is reentering the CI using
either the previous or a new value on the PERF INIT page. Following the CI
reentry, activating the data modification by pushing the execute (EXEC) key will
restart FMC predictions and allow the crew to reengage VNAV.
However, it was discovered that with certain winds entered on the DES
FORECAST page, it may not be possible to reenter a CI value on the PERF INIT
page until an approach is selected into the active flight plan.
Note:
The exact wind data entries that will trigger this anomaly are not known
at this time.
Information in this bulletin is recommended by The Boeing Company, but may not be FAA approved
at the time of writing. In the event of conflict with the FAA approved Airplane Flight Manual
(AFM), the AFM shall supersede. The Boeing Company regards the information or procedures
described herein as having a direct or indirect bearing on the safe operation of this model airplane.
March 1, 2021
