Why can it sometimes be necessary to dump kerosene in an emergency?
If a fully fuelled long-distance aircraft has to land shortly after take-off due to an emergency or a technical defect then it is necessary to dump a carefully calculated amount of kerosene at a high altitude. This only happens in absolute emergencies and requires prior authorisation by German Air Traffic Control.
Kerosene dumping can only take place from long-haul aircraft that are equipped with the necessary fuel dump systems. Air traffic control will assign a specific area – usually away from populated areas and over large bodies of water – where the aircraft may dump fuel. Usually fuel dumping takes place at an altitude of between four and eight kilometres with a flying speed of at least 500km/h. The kerosene trails behind the aircraft in a fine spray consisting of tiny droplets, most of which evaporate and are broken down into water and carbon dioxide by the sun’s radiation. No pollution is measurable on the ground.
German Air Traffic Control registers 40 events per year where fuel dumping is authorised.