Boeing 737-4Q8 N771AS

Summary

On 20 December 2008 at about 11:47 local time, a Boeing 737-4Q8 registered N771AS, operated by Alaska Airlines, was involved in an incident near Sitka, Alaska, United States. 88 people were on board and 88 had minor injuries. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

20 December 2008 at 11:47

Classification

Incident

Location

Sitka, Alaska, United States

Nearest airport

Sitka (PASI)

Coordinates

57.0472, -135.3617

Aircraft

Boeing 737-4Q8

Registration

N771AS

Category

Airplane

Engines

2

Operator

Alaska Airlines

Operating rule

Part 121: Air Carrier

Phase of flight

Not recorded

Route

Sitka → Juneau

Aircraft damage

Not recorded

Weather

VMC

Light

Night

NTSB number

ANC09IA015

88 people had minor injuries.

The placement of operating equipment in close proximity to an external heating unit's intake by ground personnel, resulting in the contamination of the airplane's cabin with carbon monoxide.

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

Read the full NTSB narrative

After departure the cabin crew reported to the captain that they were becoming nauseated. The captain noted that the departure was the first flight of the day and that the airplane had been sitting on the ramp overnight connected to an external heating unit. He said that prior to flight the first officer and cabin crew went to prepare the airplane while he remained in the operations center with paperwork. He said the first officer requested the ground crew shutdown the external heater because of exhaust fumes in the airplane's cabin. The first officer started the airplane's auxiliary power unit to provide power and heat to the airplane. The captain said that about 15 minutes later he did not detect any unusual smells or odors, and wiped his hand across seats and surfaces to detect contamination. Finding none, he felt it was safe to continue boarding. He reported that the boarding process was normal, and none of the crew or passengers reported any unusual smells or odors. When the cabin crew reported feeling nauseated, the captain determined that they were 20 minutes from their destination and decided to continue the flight rather than turn back. The captain reported that he and the first officer were symptom free, and that the first officer remained on oxygen for the remainder of the flight as a precaution. Upon arrival the flight crew all tested positive for elevated levels of carbon monoxide. The cabin of the airplane was examined and no traces of carbon monoxide were found. Tests of the ground heating unit found no anomalies, and the heat output hose was tested for CO with negative results. According to the director of safety for the operator, the contamination probably occurred when the morning ground crew started the push-back unit in the proximity of the heater's fresh air intake. As a result, the heating unit has been repositioned away from other operating equipment, and a 20-foot exhaust hose attached. Carbon monoxide detectors are now placed in the operator's aircraft during extended external heater usage.

Quoted verbatim from the NTSB record.