Kegworth Air disasterExample of multiple levels of analysisWhat 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 simulatortechnology updated but not announced

Vibration Dial 2

vibration dial small [design]

Without range marking [design]

During descent

lots of interruptionspilots can’t see the enginesno protocol: no checking/confirmation visually

from cabin• Passengers could see fire but explained it

away, perhaps also flight attendantsdiffusion of social responsibilitiesSocial distance between aircrew and pilots

crash• 900 m short

• 43+4 out of 118+8 die

At crashNot 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