A colleague of mine experienced this and I was astonished. Flying KLM from PVG to AMS a couple of hours into take off toilets became full. The pilot dumped fuel and returned to PVG. All passengers were re-booked next day. Funnily, she had the same issue fly from JFK to LHR last year. (Probability that she was on both planes - amusing)

Thinking of aviation fuel, environment, cost of re-flying passengers. I wonder why the aircraft makers not allow dumping 'contents' of 'toilet tank' (on the open sea) instead of dumping gallons of fuel.

I just wonder how often does such issues happen? Would toilet tank emptying not be checked before take off?

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    $\begingroup$ Hi and welcome. You have at least 3 different questions. Can you please edit the title and body to focus on just one of them? It's better to ask one question per post so it can be answered effectively. $\endgroup$ – ymb1 May 17 '19 at 12:25
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    $\begingroup$ I'd guess the tanks weren't full, since they are emtied before flight. But there might have been a problem with the... content delivery system to the tanks. $\endgroup$ – sweber May 17 '19 at 13:34

An aircraft with full lavatory waste tanks can not continue on it's flight as it is a requirement to have a specified number of serviceable toilets on every flight. It is usually the responsibility of the Purser or In Charge Flight Attendant to check the waste tank volume when they prepare for each flight. On most aircraft there is a control panel with a display that shows the actual waste volume.

Here are some possible reasons why the waste tanks became full:

  1. They were not checked before the fight
  2. They were not emptied on the ground
  3. They malfunctioned and ran continuously
  4. The display on the waste control panel malfunctioned

In any case these tanks can not be emptied while airborne, and the only course of action is to land and have the tanks emptied or serviced.

On a long haul flight like PVG to AMS the crew would not have been legal to continue their duty day after returning to PVG and the flight would have to be cancelled or delayed until a new rested crew could be found to operate the flight.

  • $\begingroup$ FYI: 1. gets you nice list formatting while 1) does not. Minor detail. $\endgroup$ – FreeMan May 17 '19 at 20:29

Airliner toilets cannot be emptied in flight. The valve is on the outside, and can only be accessed by ground crew. Besides, two hours of flying would not have filled the toilets. It is much more likely that the ground crew at PVG forgot to empty them before the next leg to AMS, or their toilet service cart was not working at the time.


I wonder why the aircraft makers not allow dumping 'contents' of 'toilet tank' (on the open sea) instead of dumping gallons of fuel.

If you are implying that the waste should be dumped to allow the flight to continue, then the additional complexity, weight and cost that would go into a mid-air waste-pumping device makes it completely impractical.

The waste tanks are intended to be big enough for any flight, and should start empty if the ground-crew handles it properly. A waste-pumping mechanism would need certification and regular maintenance, and take from the weight and fuel capacity of the plane. It would very rarely get used, and is better handled just by reliable ground service.

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    $\begingroup$ I think the OP meant why can't the waste tanks be dumped so that the toilets can continue to be used instead of aborting the flight. $\endgroup$ – Ward - Reinstate Monica May 17 '19 at 18:48
  • $\begingroup$ @ward The above comment answers that question. $\endgroup$ – Juan Jimenez May 20 '19 at 8:42

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