A short history of toilets at 35,000 feet – what really happens when you flush a plane loo?

Unless you’ve flown first class, or in a private jet, aircraft loos are windowless, cramped affairs that usually reek of cheap sanitizer. But they have come a long way – and rarely get the recognition they deserve.

The first flight (made by Orville Wright, although some conspiracy theorists think otherwise – more on that here), explains Aviation Global News, lasted just 12 seconds – “hardly long enough to get worked up from a bladder perspective, although one may surmise that a number two might have been on his mind”.

But before long, planes were flying for much longer. “It is obvious that someone, somewhere, was the first person to relieve themselves in an aircraft. Who was this urinary pioneer? – history does not record,” laments the website.

Some interesting facts have been recorded, however. Second World War pilots, for example, couldn’t stand the “slop bucket” loos – or “Elsans” – found on board Lancaster bombers. They often overflowed in turbulent conditions, or were tricky to use.

One unidentified airman described his hatred for the contraptions: “While we were flying in rough air, this devil’s convenience often shared its contents with the floor of the aircraft, the walls, the ceiling, and sometimes a bit remained in the container itself.

“It doesn't take much imagination to picture what it was like trying to combat fear and airsickness while struggling to remove enough gear in cramped quarters and at the same time trying to use the bloody Elsan… This loathsome creation invariably overflowed on long trips and in turbulence was always prone to bathe the nether regions of the user. It was one of the true reminders to me that war is hell.”

Airmen sometimes preferred to urinate or defecate into containers, before simply hurling their business out of a window. Some reputedly jettisoned full Elsan toilets on German targets along with their bombs – an early example of biological warfare.

James Kemper’s modern vacuum toilet wasn’t patented until the Seventies, with the first one installed by Boeing in 1982. Before that, plane loos were unwieldy boxes that utilised large quantities of blue liquid known as “Skykem” and were prone to leaking. So next time you’re queuing to use the facilities at 35,000 feet, count yourself lucky.

Kemper’s nifty device uses a little liquid, but relies on non-stick coating and vacuum suction to wash away the nastiness. The video below shows just how efficiently the vacuum works.

“The person in this video is just stupid, immature, inconsiderate, and has no life,” comments one YouTube user, beneath the clip. “I am definitely doing this on my next flight.” Quite.

Since then, there have not really been any dramatic advances in aircraft toilet technology – if it ain't broke, don't fix it. The only noteworthy item is that the toilets on Boeing's 787 Dreamliners have automatically closing lids. Oh, and some toilets are getting smaller to really cram in those paying customers.

So what does happen to all that waste? Is it jettisoned into the sky? To all those fliers who make a point of holding it in until the plane reaches European soil, prepare to be sorely disappointed.

“There is no way to jettison the contents of the lavatories during a flight,” explains Patrick Smith, a pilot and author of Cockpit Confidential, a book about air travel. “At the end of a flight, the blue fluid, along with your contributions to it, are vacuumed into a tank on the back of a truck. (The truck driver’s job is even lousier than the co-pilot’s, but it pays better.)

“The driver then wheels around to the back of the airport and furtively offloads the waste in a ditch behind a parking lot... Just kidding. In truth I don’t know what he does with it. Time to start a new urban legend.”

There is one caveat, however. It is impossible to empty passengers' waste from an aircraft intentionally, but not by mistake.

“A man in California once won a lawsuit after pieces of blue ice fell from a plane and came crashing through the skylight of his sailboat,” added Captain Smith. “A leak, extending from a toilet’s exterior nozzle fitting, caused runoff to freeze, build, and then drop like a neon ice bomb. If you think that’s bad, a 727 once suffered an engine separation after ingesting a frozen chunk of its own leaked toilet waste, inspiring the line ‘when the s*** hits the turbofan.’”