|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||1801 To 2400|
|Locale Reference||navaid : abq.vortac|
|Altitude||msl single value : 37000|
|Controlling Facilities||artcc : zab.artcc|
|Operator||common carrier : air carrier|
|Make Model Name||B737-300|
|Operating Under FAR Part||Part 121|
|Flight Phase||cruise : level|
|Affiliation||company : air carrier|
|Function||flight crew : captain|
oversight : pic
|Experience||flight time last 90 days : 170|
flight time total : 22600
flight time type : 21000
|Affiliation||company : air carrier|
|Function||flight crew : first officer|
|Experience||flight time last 90 days : 150|
flight time total : 12000
flight time type : 500
|Anomaly||aircraft equipment problem : critical|
non adherence : company policies
non adherence : far
non adherence : published procedure
|Independent Detector||other other : obs 4|
|Resolutory Action||flight crew : overcame equipment problem|
|Problem Areas||Flight Crew Human Performance|
We noticed the cabin rate increasing at cruise at approximately 100 FPM with a lower than normal differential pressure. Initially going to packs on high corrected the 100 FPM increase. We used standby mode in cruise as a precaution and switched back to automatic after the cabin started to descend properly during descent. The next leg everything went fine in automatic with a maximum cruise altitude of FL270. The next morning, the captain who took out aircraft number called me at the hotel to see if we had any pressurization problems with the aircraft. They had experienced an automatic mode failure without it switching to 'standby' and had to descend to get the cabin pressure under control. On the initial flight to tul, there was WX at destination and a lot of coordination with dispatch about en route WX for the second leg, so the anomaly with the pressurization on the first leg was not written up. On the termination postflt, the first officer found evidence of a bird strike, so that was entered into the logbook and maintenance was notified. Obviously looking back, a write-up by me on the initial leg would have broken the chain of events that complicated the next crew's day. The routine nature of dealing with the initial anomaly and subsequent coordination effect with dispatch reference the WX, simply pushed that occurrence down my list of priorities.
Original NASA ASRS Text
Title: A B737-300 FLT CREW FAILS TO MAKE A LOGBOOK ENTRY REGARDING A MALFUNCTION EXPERIENCED WITH THEIR PRESSURIZATION SYS ON A PREVIOUS LEG. THE NEXT PIC HAS A PROB WITH THE SYS AND CALLS THE FIRST CAPT ON HIS LAYOVER TO FIND OUT IF HE HAD A PROB WITH THE ACFT.
Narrative: WE NOTICED THE CABIN RATE INCREASING AT CRUISE AT APPROX 100 FPM WITH A LOWER THAN NORMAL DIFFERENTIAL PRESSURE. INITIALLY GOING TO PACKS ON HIGH CORRECTED THE 100 FPM INCREASE. WE USED STANDBY MODE IN CRUISE AS A PRECAUTION AND SWITCHED BACK TO AUTO AFTER THE CABIN STARTED TO DSND PROPERLY DURING DSCNT. THE NEXT LEG EVERYTHING WENT FINE IN AUTO WITH A MAX CRUISE ALT OF FL270. THE NEXT MORNING, THE CAPT WHO TOOK OUT ACFT NUMBER CALLED ME AT THE HOTEL TO SEE IF WE HAD ANY PRESSURIZATION PROBS WITH THE ACFT. THEY HAD EXPERIENCED AN AUTO MODE FAILURE WITHOUT IT SWITCHING TO 'STANDBY' AND HAD TO DSND TO GET THE CABIN PRESSURE UNDER CTL. ON THE INITIAL FLT TO TUL, THERE WAS WX AT DEST AND A LOT OF COORD WITH DISPATCH ABOUT ENRTE WX FOR THE SECOND LEG, SO THE ANOMALY WITH THE PRESSURIZATION ON THE FIRST LEG WAS NOT WRITTEN UP. ON THE TERMINATION POSTFLT, THE FO FOUND EVIDENCE OF A BIRD STRIKE, SO THAT WAS ENTERED INTO THE LOGBOOK AND MAINT WAS NOTIFIED. OBVIOUSLY LOOKING BACK, A WRITE-UP BY ME ON THE INITIAL LEG WOULD HAVE BROKEN THE CHAIN OF EVENTS THAT COMPLICATED THE NEXT CREW'S DAY. THE ROUTINE NATURE OF DEALING WITH THE INITIAL ANOMALY AND SUBSEQUENT COORD EFFECT WITH DISPATCH REF THE WX, SIMPLY PUSHED THAT OCCURRENCE DOWN MY LIST OF PRIORITIES.
Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.