<< >> NASA ASRS Report 149575, June 1990

Air carrier medium large transport had both packs trip off at FL310 between lax and oak. Flight crew started descent, then were able to rest pack controls and continue.

Attributes
ACN	149575
Time
Date	199006
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : gmn
State Reference	CA
Altitude	msl bound lower : 25000 msl bound upper : 31000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zla
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : atp pilot : private pilot : instrument
ASRS Report	149575
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 9500 flight time type : 550
ASRS Report	149576
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa
Resolutory Action	flight crew : declared emergency flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

While cruising at FL310 the left AC pack tripped off followed a few seconds by the right pack tripping off. O2 masks were donned and ATC notified. Descent began while squawking 7700. Passing between FL280 and FL270 a reset of the packs was tried and pressurization reestablished. Notified ATC and stopped descent at FL250. Flight continued to destination after contacting company through sfo operations. Cabin rate of climb reached 1500 FPM prior to being reset. Maximum cabin altitude was 8500'. Event ended in normal descent, approach and landing. Emergency checklists were completed after descent established.

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Original NASA ASRS Text

Title: ACR MLG HAD BOTH PACKS TRIP OFF AT FL310 BETWEEN LAX AND OAK. FLT CREW STARTED DESCENT, THEN WERE ABLE TO REST PACK CTLS AND CONTINUE.

Narrative: WHILE CRUISING AT FL310 THE LEFT AC PACK TRIPPED OFF FOLLOWED A FEW SECS BY THE RIGHT PACK TRIPPING OFF. O2 MASKS WERE DONNED AND ATC NOTIFIED. DSNT BEGAN WHILE SQUAWKING 7700. PASSING BTWN FL280 AND FL270 A RESET OF THE PACKS WAS TRIED AND PRESSURIZATION REESTABLISHED. NOTIFIED ATC AND STOPPED DSNT AT FL250. FLT CONTINUED TO DEST AFTER CONTACTING COMPANY THROUGH SFO OPS. CABIN RATE OF CLB REACHED 1500 FPM PRIOR TO BEING RESET. MAX CABIN ALT WAS 8500'. EVENT ENDED IN NORMAL DSNT, APCH AND LNDG. EMER CHKLISTS WERE COMPLETED AFTER DSNT ESTABLISHED.

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.