Reply to an Aviation Medico          

(lost his original Email)

 

The thrust of his comments were that: Murphy's Law of Thermodynamics: Things get worse under pressure.

 

 

 

 

 

Reply:

I take a lot of your points. Hypoxia is unlikely, ingestion of toxic smoke is a possibility. But the built-in designed essence of the smoke checklist is that eventually you get down to a bare-bones electrical configuration. If you're then struggling to retain control on partial panel and still the situation's not improving - it's just a rotten break. The likelihood of an unrecoverable unusual attitude is very high.

My basic contention is that a third man (the old Flt Eng) would be a boon in off-loading the pilots in such a circumstance. I always found it to be so. I'm afraid that the SR111 crew were just overloaded into a loss of control accident in IMC that was predicated by the eliminatory type of smoke checklist that is common to most multi-engined aircraft.

What is required is an immediately selectable (one switch),yet minimally basic, electrical configuration from which you can then start to ADD buses and systems until the problem recurs. The way in which it's traditionally done (monitoring OFF systems and buses piece by piece) never ever was going to stop the build-up of smoke and fumes in the long interim. I know from experience that it was always hard to tell when you'd had success after the smoke and fumes have built up.

There seemed to be always the lingering taste and smell that was impossible to dispel via the "Smoke and Fumes Elimination Checklist"

My suggestion straight off kills most possibilities of the situation compounding yet allows you to judiciously reintroduce necessary systems, as required, over a calmer, less frenetic period.

I'd suggest that it was a penultimate checklist step that was the undoing of the SR111 crew. They may have actuated the wrong switch? They either lost their vital attitude indicators and had nowhere to go from there or they allowed the aircraft to wander into an unrecoverable attitude - then pulled the wings off it in recovery. Either answer would explain the lack of FDR data below 2500 meters.

I'd be very surprised if it is attributed to the cockpit becoming so full of smoke that they couldn't have retained sufficient interior visibility. The MD11 does have ram air venting once depressurized.

Dagger Dirk

 
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