One thing I guess a lot of people wonder is: what happens you flush the toilet in an aeroplane?
Does it fall out the belly of the plane and disintegrate? :)
A kiwi woman complains that "aeroplanes are taking a s**t on her driveway", beneath the flight path. Is there any way this might actually happen?
I can speak for the most common commercial models (the 7x7s, A3xxs and the like) via an engineer friend. All of these models flush into a tank which is emptied on the turnaround.
For Vulcans, I can speak with first hand experience. Each crew member had a stainless steel "pee tube", a funnel, which fed into a rubber bladder. They are emptied and cleaned during the after flight inspection.
I was changing a radio under the rear crew table where the electronics, navigator and radar operator sat. This involved squeezing down behind the seats to lie under the table, disconnecting and unfastening the radio, hauling onto your chest then pushing it up onto one of the seats and reversing the process to get out from under the table.
As I pushed the radio up onto the seat, I knocked one of the pee tubes and bladders out of it's clip holder which then emptied the contents onto me and the radio.
The bladder had not been emptied - and the aircraft had been in the hangar for 3 weeks!
Of course, it was my job to clean up the mess - lots of french chalk as urine is very corrosive to airframes.
The radio also needed writing up so I tagged it as "suspect urine ingress".
The same radio came back to me with a tag attached saying (and this might work only for non-American English speakers) - "are you taking the p*ss?".
Yeuch.
On newer airliners it is fed into a septic tank. Decades ago, it was simply dropped overboard. Before the introduction of vacuum flush toilets, water flushing was used which involved big tanks which could leak their content overboard.
The Boeing 727 had at least two cases where the right engine was lost as the ultimate consequence of this malfunction. Since the lavatory piping was on the right side, ice which had built up there could break loose and be ingested by the engine behind. If the ice block was large enough, it could damage the fan, and the resulting imbalance could shake the engine off. Boeing engineers designed the engine mount with a rated break point so hefty engine vibrations would not damage the rest of the plane.
Glider pilots have all kinds of means to lighten themselves when nature calls. The product of this is then thrown overboard - that is what the small sliding window on the left side of a glider canopy is for. A friend of mine uses plastic bags and once forgot to take one with him in a competition flight. He realized his omission just before he was aero-towed on his way and asked bystanders for help. Someone handed him his plastic bag which had been used to hold apples - and was perforated. My friend realized this detail too late, but very soon after he began using the bag.
It is stored and then disposed of when plane touches down.
From Yahoo! Answers and Wikipedia: Aircraft lavatory.
