Re: Aircraft Toilets

From: (Christopher Davis)
Organization: Venus Equilateral Communications Company
Date:         02 May 95 13:27:43 
References:   1
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NH> == Neil Harding <>

 NH> My girlfriend does not believe me when I tell her that certain older,
 NH> currently flying airliners deposit their sanitary waste out of the
 NH> back of the aircraft during flight. Which leads to the phenomenon
 NH> known as 'blue ice'.

 NH> Please could someone inform me of types of aircraft which do this, as
 NH> this matter is currently forming a bet for a dinner!

To the best of my knowledge, unlike trains, no airliner is (or ever will
be) designed to dump "that stuff" out of the vehicle while in motion.
(Aside: this is why train toilets may be marked "not for use while in

However, due to the vagaries of any mechanical system, airliners may have
leaks in the waste disposal system (caused by improperly closed drain
ports, broken valves, and the like) which result in the formation of "blue
ice" at altitude.

This typically breaks off when the plane is on a landing approach, where
the turbulence is more severe (and the temperatures higher).

Types that have done this in the past include a United DC-10 which
"dropped one" on approach to Seattle-Tacoma a little while back.

Christopher Davis * <> * <URL:>
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