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Air carrier medium large transport had to request a lower altitude when 1 air conditioning pack could not keep up with the airflow demand.
| Attributes | |
| ACN | 195200 |
| Time | |
| Date | 199111 |
| Day | Fri |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : slt |
| State Reference | PA |
| Altitude | msl bound lower : 10000 msl bound upper : 20000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Dusk |
| Aircraft 1 | |
| Controlling Facilities | artcc : zob |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | climbout : intermediate altitude |
| Route In Use | enroute airway : j584 |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : cfi pilot : atp |
| Experience | flight time last 90 days : 120 flight time total : 6800 flight time type : 100 |
| ASRS Report | 195200 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | aircraft equipment problem : less severe inflight encounter : weather |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified |
| Resolutory Action | flight crew : overcame equipment problem |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
We were climbing to cruise altitude, and we were passing through FL200 (as I remember), when the cabin altitude light came on. I was flying the aircraft, and the captain was working the radios. He asked center for a lower altitude, and we were given FL200. The captain asked for 10000 ft. We were then given that, and I made an average descent rate (1500 FPM) descent to 10000 ft. After a few mins, the pressurization seemed normal, so the captain asked for a final altitude of 17000 ft, which we were given, and were able to maintain without problems, to our destination. The captain did not declare an emergency, and there was no need to return to our departure airport. Mechanical reason why the cabin altitude light came on. The right pack was MEL'ed and off. We were in light icing conditions, and with the engine and airfoil de-ice and anti- icing system on, the 1 pack could not keep up with the climb rate of the aircraft to pressurize the cabin.
Original NASA ASRS Text
Title: ACR MLG HAD TO REQUEST A LOWER ALT WHEN 1 AIR CONDITIONING PACK COULD NOT KEEP UP WITH THE AIRFLOW DEMAND.
Narrative: WE WERE CLBING TO CRUISE ALT, AND WE WERE PASSING THROUGH FL200 (AS I REMEMBER), WHEN THE CABIN ALT LIGHT CAME ON. I WAS FLYING THE ACFT, AND THE CAPT WAS WORKING THE RADIOS. HE ASKED CENTER FOR A LOWER ALT, AND WE WERE GIVEN FL200. THE CAPT ASKED FOR 10000 FT. WE WERE THEN GIVEN THAT, AND I MADE AN AVERAGE DSCNT RATE (1500 FPM) DSCNT TO 10000 FT. AFTER A FEW MINS, THE PRESSURIZATION SEEMED NORMAL, SO THE CAPT ASKED FOR A FINAL ALT OF 17000 FT, WHICH WE WERE GIVEN, AND WERE ABLE TO MAINTAIN WITHOUT PROBLEMS, TO OUR DEST. THE CAPT DID NOT DECLARE AN EMER, AND THERE WAS NO NEED TO RETURN TO OUR DEP ARPT. MECHANICAL REASON WHY THE CABIN ALT LIGHT CAME ON. THE R PACK WAS MEL'ED AND OFF. WE WERE IN LIGHT ICING CONDITIONS, AND WITH THE ENG AND AIRFOIL DE-ICE AND ANTI- ICING SYS ON, THE 1 PACK COULD NOT KEEP UP WITH THE CLB RATE OF THE ACFT TO PRESSURIZE THE CABIN.
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.