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Flight continuation after automatic deployment of passenger oxygen masks due to loss of automatic pressure controller for cabin pressurization system.
| Attributes | |
| ACN | 203676 |
| Time | |
| Date | 199202 |
| Day | Fri |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | airport : den |
| State Reference | CO |
| Altitude | msl bound lower : 10000 msl bound upper : 18000 |
| Environment | |
| Flight Conditions | Mixed |
| Light | Night |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | climbout : intermediate altitude descent other |
| Route In Use | enroute airway : zdv |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 8500 flight time type : 1000 |
| ASRS Report | 203676 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp pilot : commercial pilot : instrument |
| Experience | flight time last 90 days : 180 flight time total : 2900 flight time type : 250 |
| ASRS Report | 203739 |
| Events | |
| Anomaly | aircraft equipment problem : critical non adherence : far non adherence other other anomaly other |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : overcame equipment problem other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | Pilot Deviation other |
Narrative:
On night departure from den during climb out and turn on course, we noticed several problems. My altimeter was erratic and occasionally showing an off flag. We also had an intermittent off warning light on the mach trim system. The automatic pressure controller automatic-fail light came on, and switched automatically to standby, and I could not engage the autoplt. While troubleshooting all of this and climbing through approximately FL180 we realized that the cabin was not pressurizing properly, stopped the climb, asked for and received a descent clearance back down to 10000 ft from center. I flew a normal descent to 10000 ft because of the small amount of altitude change needed. Prior to our reaching 10000 ft the cabin altitude horn sounded and shortly thereafter the passenger oxygen masks deployed automatically. While at 10000 ft cabin pressure control was regained in the manual mode. I called our maintenance via commercial radio to discuss the system problems. It was his opinion that they were all related to the central air data computer. We switched back to standby on the automatic pressure controller to verify control in that mode, and reset the passenger oxygen system. After conferring with the first flight attendant as to the condition of the cabin, and having maintenance's ok to continue safely, I elected to continue the flight. We asked for and received a clearance to FL330 and climbed on course for our destination. While leveling at FL330 our dispatch contacted us by SELCAL and I discussed the situation with him and of our maintenance's and my joint decision to continue. The rest of the flight was completed without incident. Even an older style aircraft can have many system affected by the air data computer. I think we, as a crew, handled this in a professional manner and completed our flight safely. Supplemental information from acn 203739: we switched back to standby on the automatic pressure controller to verify control in that mode and reset the passenger oxygen system with the t-handle in the floor.
Original NASA ASRS Text
Title: FLT CONTINUATION AFTER AUTOMATIC DEPLOYMENT OF PAX OXYGEN MASKS DUE TO LOSS OF AUTOMATIC PRESSURE CTLR FOR CABIN PRESSURIZATION SYS.
Narrative: ON NIGHT DEP FROM DEN DURING CLB OUT AND TURN ON COURSE, WE NOTICED SEVERAL PROBLEMS. MY ALTIMETER WAS ERRATIC AND OCCASIONALLY SHOWING AN OFF FLAG. WE ALSO HAD AN INTERMITTENT OFF WARNING LIGHT ON THE MACH TRIM SYS. THE AUTO PRESSURE CTLR AUTO-FAIL LIGHT CAME ON, AND SWITCHED AUTOMATICALLY TO STANDBY, AND I COULD NOT ENGAGE THE AUTOPLT. WHILE TROUBLESHOOTING ALL OF THIS AND CLBING THROUGH APPROX FL180 WE REALIZED THAT THE CABIN WAS NOT PRESSURIZING PROPERLY, STOPPED THE CLB, ASKED FOR AND RECEIVED A DSCNT CLRNC BACK DOWN TO 10000 FT FROM CTR. I FLEW A NORMAL DSCNT TO 10000 FT BECAUSE OF THE SMALL AMOUNT OF ALT CHANGE NEEDED. PRIOR TO OUR REACHING 10000 FT THE CABIN ALT HORN SOUNDED AND SHORTLY THEREAFTER THE PAX OXYGEN MASKS DEPLOYED AUTOMATICALLY. WHILE AT 10000 FT CABIN PRESSURE CTL WAS REGAINED IN THE MANUAL MODE. I CALLED OUR MAINT VIA COMMERCIAL RADIO TO DISCUSS THE SYS PROBLEMS. IT WAS HIS OPINION THAT THEY WERE ALL RELATED TO THE CENTRAL AIR DATA COMPUTER. WE SWITCHED BACK TO STANDBY ON THE AUTO PRESSURE CTLR TO VERIFY CTL IN THAT MODE, AND RESET THE PAX OXYGEN SYS. AFTER CONFERRING WITH THE FIRST FLT ATTENDANT AS TO THE CONDITION OF THE CABIN, AND HAVING MAINT'S OK TO CONTINUE SAFELY, I ELECTED TO CONTINUE THE FLT. WE ASKED FOR AND RECEIVED A CLRNC TO FL330 AND CLBED ON COURSE FOR OUR DEST. WHILE LEVELING AT FL330 OUR DISPATCH CONTACTED US BY SELCAL AND I DISCUSSED THE SITUATION WITH HIM AND OF OUR MAINT'S AND MY JOINT DECISION TO CONTINUE. THE REST OF THE FLT WAS COMPLETED WITHOUT INCIDENT. EVEN AN OLDER STYLE ACFT CAN HAVE MANY SYS AFFECTED BY THE AIR DATA COMPUTER. I THINK WE, AS A CREW, HANDLED THIS IN A PROFESSIONAL MANNER AND COMPLETED OUR FLT SAFELY. SUPPLEMENTAL INFO FROM ACN 203739: WE SWITCHED BACK TO STANDBY ON THE AUTO PRESSURE CTLR TO VERIFY CTL IN THAT MODE AND RESET THE PAX OXYGEN SYS WITH THE T-HANDLE IN THE FLOOR.
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.