AIRWORTHINESS IS PARTICULARLY PROBLEMATIC

"The proponents of this change rely heavily on the technical merits of the B777....We do point out that two of the engine models currently used on the B777 have already been the subject of FAA Airworthiness Directives mandating the redesign and replacement of important subassemblies because of in service failures....No one involved in the design or certification of B777 aircraft equipped with these engines for ETOPS...anticipated these problems. Studies are often different than actual experience...."

(Allied Pilots Association, in Air Safety Week, jun.21, 1999)

PARAMETERS IN THE RISK MODEL

It's time to consider actual forecast winds rather than assuming "still-air" conditions and,  time-limited aircraft systems should be required to function throughout maximum forecast diversion times as well. Furthermore : on the remaining engine.

• A very long flight increases risks :

Longer mean diversion time
Wind impact on the real diversion time
No readable data on the real "In Flight Shut Down" at maximum Continuous thrust
No tests yet of the effect of severe icing or rain at single-engine altitudes.

• A single engine  isn't sufficient to generate warmth

After loosing one engine, the ability to generate warm cabine air depends on the remaining engine No bleed air means that cabin temperatures will drop to outside temperature. Over the poles it can reach -75°F...
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