ASN Wikibase Occurrence # 357409
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| Date: | Sunday 12 May 1996 |
| Time: | 20:25 LT |
| Type: |  Boeing 727-290 |
| Owner/operator: | American Trans Air |
| Registration: | N775AT |
| MSN: | 21511/1439 |
| Year of manufacture: | 1979 |
| Total airframe hrs: | 47305 hours |
| Engine model: | P&W JT8D-17 |
| Fatalities: | Fatalities: 0 / Occupants: 112 |
| Aircraft damage: | None |
| Category: | Serious incident |
| Location: | Indianapolis, IN -
 United States of America
|
| Phase: | En route |
| Nature: | Unknown |
| Departure airport: | Chicago, IL (KMDW) |
| St. Petersburg, FL (KPIE) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
Upon reaching a cruise altitude of 33,000 feet, the cabin altitude warning horn sounded. The captain noticed the right air conditioning pack was off and he, along with the flight engineer, attempted to reinstate the pack without using a checklist. The cabin altitude continued to climb to 14,000 feet at which time the warning lights illuminated and the oxygen masks deployed in the cabin. While attempting to correct the cabin altitude, the flight engineer inadvertently opened the outflow valve resulting in a rapid loss of cabin pressure. The captain, the flight engineer, and the lead flight attendant all subsequently became unconscious due to hypoxia. The captain had delayed donning his oxygen mask. The flight engineer became unconscious after reviving the flight attendant. The first officer, who had only 10 hours of flight time in the airplane, had donned his oxygen mask when the warning horn first sounded, maintained consciousness, and was able to initiate an emergency descent. During the emergency descent the captain, the flight engineer, and the attendant regained consciousness, and an emergency landing was made at Indianapolis, Indiana. The airplane was inspected and flight tested the next day. The airplane's pressurization system functioned with no anomalies.
Probable Cause: the failure of the captain and flight engineer to utilize a checklist to troubleshoot a pressurization system problem, and the flight engineer's improper control of the pressurization system which resulted in an inadvertent opening of the outflow valve and subsequent airplane decompression.
Accident investigation:
 |
|
Sources:
NTSB CHI96IA157
History of this aircraft
Other occurrences involving this aircraft
| 13 April 1988 | N291AS | Alaska Airlines | 0 | Portland, OR | |
min |
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 13-Mar-2024 17:35 | ASN Update Bot | Added |
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