What happens to kerosene in water

When planes dump tons of kerosene

Aircraft have to discharge large amounts of kerosene again and again. But why? And what are the consequences for people and nature?

The so-called quick release heats the mind once again. "That only happens in emergencies. Then you can't avoid draining the fuel," explains professional pilot Andreas K .. "However, this only happens if the aircraft has to land prematurely, for example because a passenger has a heart attack on board shortly after take-off and needs medical help. "

Before the aircraft could land, the weight had to be reduced, otherwise the landing gear could be damaged, explains the expert. "And long-haul pilots - and only this one - have the appropriate device to pump out the kerosene in such cases. It takes a few minutes and for this the aircraft has to circling over a sparsely populated area and at a given altitude."

Such occurrences quickly landed in the media because of concern among the people who live in the area. "Most of the fuel evaporates, according to experts," said the pilot. This also results from the planning approval decision for the expansion of Berlin Schönefeld Airport. According to this, most of the kerosene would already evaporate in the higher air layers. The fuel remains in the atmosphere until it is converted into water and carbon dioxide by the energy of the sun, it says.

So far, there is a lack of knowledge as to whether and, if so, to what extent people and the environment are burdened by this emergency measure.

When is an emergency present?

Ultimately, it is up to the pilots to decide when there is an emergency. Sometimes, as those responsible, they also have to turn around when there is actually no emergency, but one could become one. "This is the case, for example, when there is a technical situation in which it is uncertain whether it could become a danger. The pilots then play it safe and prefer not to fly the machine in this condition for ten hours Atlantic, but turn back, "says the former Air Berlin pilot.

However, fuel is never carelessly blown into the atmosphere, only when it cannot be avoided. After all, fuel is also very expensive, he adds. "Before we risk human lives, we turn around and let off fuel to land safely."

In such emergencies, air traffic control gives the pilot a clearly defined area and determines the altitude they must adhere to. The minimum flight altitude is 1830 meters. The regions with heavily frequented airports such as Frankfurt and Munich are most frequently affected.

A Lufthansa Airbus A380 just had to discharge 40 tons of kerosene over a forest area in Rhineland-Palatinate, shortly after take-off in Frankfurt. The machine was supposed to fly non-stop to Houston / Texas, but then the pilots noticed problems with the landing gear. So that the machine could land safely, the pilots let the large amounts of fuel off over the area of ​​the Palatinate Forest.

Why don't short- and medium-haul planes run out of fuel?

The reason is the maximum allowed landing weight. This is not a problem for short and medium-haul pilots, explains pilot Andreas K .: "The maximum landing weight is also below the maximum take-off weight, which would mean that you can only land again when the excess kerosene has been used up. But in emergencies this is allowed. You only have to do a thorough inspection of the landing gear to see if it has been damaged. "

For long-haul pilots, some of whom have more than 100 tons of kerosene on board, this is no longer possible. They actually have to reduce their weight significantly before landing, "explains the expert.

"By the way, there is a widespread misconception. Many people believe that they observe that planes let off fuel on their approach. But that is not true. On days with high humidity, water condenses on the wing tips because of the pressure difference between the top and bottom of the wing You can see that as a stripe. It's pure water vapor from the air, not kerosene, "explains the pilot.

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