KLM – Planning Drinking Water for Airplanes #SWI2005

Part of the planning of each KLM flight consists in determining the quantity of drinking water to take on board. Risking a water shortage is not an option, whereas a surplus will cost unnecessary extra fuel. However, reading off the level of the water tanks can not be done accurately: on most airplanes, the water level is displayed rounded off to the nearest 1/8th of a tank. This affects the accuracy of the forecast data and makes it impossible to fill the tank with an exact amount of water. For this reason, KLM maintains a safe but expensive margin on the amount of drinking water on board.

As an example, consider the stretch of Amsterdam – New York. On this trip, taking one liter of extra water on board would cost about EUR 0.10. Consistently rounding off to the next highest one-eighth of a tank would mean taking 100 liters of water in surplus on average. On a yearly basis, this would add up to EUR 7,500.00 for just this one destination. Could a strategy be devised, given the described handicap, which could enable KLM to always take a sufficient quantity of drinking water while minimizing the costs of the safety margin?