Boeing 727-290 N775AT

Summary

On 13 May 1996 at about 01:25 local time, a Boeing 727-290 registered N775AT, operated by American Trans Air, was involved in an incident near Indianapolis, Indiana, United States. 112 people were on board and 11 had minor injuries. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

13 May 1996 at 01:25

Classification

Incident

Location

Indianapolis, Indiana, United States

Coordinates

39.7300, -86.2906

Aircraft

Boeing 727-290

Registration

N775AT

Category

Airplane

Engines

3

Operator

American Trans Air

Operating rule

Part 121: Air Carrier

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Chicago → St. Petersburg

Aircraft damage

Not recorded

Weather

VMC

Light

Night/Dark

NTSB number

CHI96IA157

11 people had minor injuries.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.