Re: Emergency landing on water ?

Date:         04 Dec 96 02:42:17 
From: (C. Marin Faure)
Organization: Northwest Nexus Inc.
References:   1
Followups:    1
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In article <airliners.1996.2615@ohare.Chicago.COM>, (Alexander Weber) wrote:

> In the case of the fiasco near Comoras Islands the weather appeared
> fine (full visibility, no/small waves on the water) and because they
> ran simply out of fuel there is no reason to assume any other
> technical problem. I could also see a fuel-explosion at the rear of
> the aircraft while it broke up, so I assume the APU was still working
> and they had still electricity and hydraulics to control the plane
> (eyewitness reported they heard that at least one engine was off, but
> there was a little engine noise - the APU?).

The 767, like all ETOPS aircraft, have Ram Air Turbines (RATs) that extend
automatically from the belly of the plane into the slipstream if all
normal sources of hydraulic and/or electrical power are lost (the pilots
can deploy them, too.)  These "propeller-on-a-stick" devices provide
sufficient power to  operate the necessary flight controls to safely
maneuver the plane in the event of a hydraulic and/or electical loss,
which you would certainly have if the plane ran out of fuel and all the
engines (and APU) have shut down.  This is what allowed the flight crew of
the Air Canada 767 that ran dry to make a "normal" descent, approach, and
touchdown at Gimli back in the early 1980s.  They had full control all the
way down, extended the gear, and had wheelbrakes, although without reverse
thrust the landing roll was extremely long.

The APU is generally not audible in the cabin; it's usually running when
passengers get on board their plane, but about the only sound you hear is
the hum and whine of the air conditioning/heating system.  Anyway, I
suspect that the airstream noise of a descending, powerless airplane would
drown out any sound of the APU if it was running in the air.

C. Marin Faure
   author, Flying a Floatplane