Kegworth Air disaster

Example of multiple levels of analysis

What causes a plane to crash? [1 min.]

What causes a plane to crash?

• A laundry list is required, or, a swiss cheese loaf lined up

• A lot, in safety critical systems

Kegworth Air Disaster

• Why?– Near Ritter, Baxter

& Churchill– A lovely example– Often used

Storyline

• Flight, jan 1989, Heathrow to Belfast, Midland 192

• Experienced pilots, new plane (737)

• Part of one of the safest systems in the world

• Upon take-off, no problems

• Shuddering, fire in an engine at ~10 min.

• Shut off #2 engine, RHS (the good one!)

• This is the pilot error

Hardware and Mischancebadly designed new engine, failure at 3 months,

approx. t=300 h, should be t=500,000 h, not tested at altitude

/unlucky choice of diversion airport [BMI hub]

Auto throttle problem

poor mental model of plane [system](turned off good engine, which disengaged autothrottled, solving the judder problem)

lack of engine feedback [interface design]

Vibration Dial 1

vibration dial harder to read [design]

vibration dial not required to fly [regulation]

dial and plane not trained with simulator

technology updated but not announced

Vibration Dial 2

vibration dial small [design]

Without range marking [design]

During descent

lots of interruptions

pilots can’t see the engines

no protocol: no checking/confirmation visually from cabin

• Passengers could see fire but explained it away, perhaps also flight attendantsdiffusion of social responsibilities

Social distance between aircrew and pilots

crash

• 900 m short

• 43+4 out of 118+8 die

At crash

Not documented: noise abatement hillocks

Afterwards

• If any 13or 3 missing, no loss of life• What was the pilot error?• Thus, systems require understanding

people, technology, and systems and environment

References

• Wikipedia on kegworth

• BBC. (1991). Fatal error: Taking liberties [television series].

• Youtube has videos as well