Accident · 2000-01-31

What the record says

Event date

2000-01-31

Event type

Accident

Highest injury level

Fatal injury

Aircraft

Douglas MD-83 (N963AS)

Operating rule

Part 121

Operator

ALASKA AIR INC Operator named in NTSB report

Operated by (per NTSB report)

ALASKA AIRLINES INC

Probable cause

A loss of airplane pitch control resulting from the in-flight failure of the horizontal stabilizer trim system jackscrew assembly's acme nut threads. The thread failure was caused by excessive wear resulting from Alaska Airlines' insufficient lubrication of the jackscrew assembly. Contributing to the accident were Alaska Airlines' extended lubrication interval and the Federal Aviation Administration's (FAA) approval of that extension, which increased the likelihood that a missed or inadequate lubrication would result in excessive wear of the acme nut threads, and Alaska Airlines' extended end play check interval and the FAA's approval of that extension, which allowed the excessive wear of the acme nut threads to progress to failure without the opportunity for detection. Also contributing to the accident was the absence on the McDonnell Douglas MD-80 of a fail-safe mechanism to prevent the catastrophic effects of total acme nut thread loss.

Flight crew

Flight-crew details for this event aren't in the NTSB database extract we hold (its coverage starts with 2008 events) — a gap in our data, not an absence of crew.