Why are airplanes designed this way

Federal Aviation Office

When is a quick fuel drain necessary?

Fuel dumping is an emergency measure that does not occur in regular flight operations and is only used in exceptional or emergency situations. It becomes necessary when an aircraft takes off with a landing weight greater than the permitted landing weight and a problem occurs that requires the aircraft to land directly. For this, the flight crew has to declare an urgency or emergency situation.

Unavoidable circumstances / reasons which force the flight crew to return or to land immediately at a suitable airport and thus the flight crew to make a decision in favor of a rapid fuel discharge are diverse and include, among other things

  • medical emergencies on board,
  • technical malfunctions (e.g. on engines, hydraulics, electrics, landing gear, flight controls, cabin pressure, bird strikes, etc.)

All cases of rapid fuel dumping and premature termination of the flight ultimately serve to rule out a hazard.

Which specific situations can lead to this?

An example for simplification:

A long-haul flight from Frankfurt to New York takes approximately 7 to 8 hours. The aircraft consumes an average of 80–100 tons of kerosene for this. This amount of fuel plus the amount of “reserve” fuel is in the aircraft's fuel tanks shortly before take-off from Frankfurt.

The following applies in principle: When taking off on the above-mentioned long-haul flight, the weight of an aircraft with a high number of passengers will be close to its maximum allowable take-off weight.

However, since far higher forces occur via the landing gear into the structure of the aircraft when it touches down on the runway, its maximum permissible landing weight is always smaller than its take-off weight in the structural design. If one of the above situations occurs immediately after the aircraft has taken off or after only a short flight time, it may be necessary to bring the aircraft safely back onto the ground as quickly as possible.

In order to reduce the total weight of the aircraft, in such emergencies the only measure that can be taken to land the aircraft safely and quickly is to let off the fuel.

However, the discharge of fuel is only permitted if the flight crew has declared an urgency or emergency situation.

Which aircraft have emergency fuel dump devices?

Emergency fuel dump (also known as "Fuel Dumping" or "Fuel Jettison") usually plays. only plays a role for long-haul flights, as aircraft types are used that have a larger tank volume and thus have a wider range of uses in terms of range and transport of fuel (e.g. Airbus A340, A380 or Boeing B747, B767 and B777). However, some smaller aircraft and in the military sector in particular combat aircraft have such devices.

What happens to aircraft without a deflation device in an emergency?

Short- and medium-haul aircraft typically do not have a device for deflating fuel. As a rule, the difference between the maximum allowable take-off weight and the maximum allowable landing weight for these aircraft is significantly smaller or nonexistent. If time is a decisive factor (a quick landing is necessary), a so-called "overweight landing" can be carried out after weighing all the advantages and disadvantages as well as the risks.

Why are not all aircraft designed in such a way that landing is possible even at maximum weight?

Especially in the case of long-haul aircraft that have to carry large amounts of fuel with them, a corresponding design of the structure of the aircraft and the landing gear would theoretically be possible, but would result in a greater weight of the aircraft, which in turn results in higher fuel consumption and a reduction in the range of the Aircraft.

Who decides whether to carry out a fuel emergency discharge?

Since the fuel drain is a very rare emergency procedure that is caused by factors that cannot be influenced, the cockpit crew generally decides whether a rapid fuel drain is necessary.

She is directly responsible for the safety of passengers, crew and aircraft. That is why only the crew assess the emergency and only they decide how to deal with the current situation. The final decision on board is made by the pilot in charge ("commanders").

The question of "whether" (kerosene is drained) and also "how much" (amount of fuel to be drained) can only be answered by the cockpit crew. When making their decision, the pilots observe the manuals and emergency procedures that have been drawn up by the manufacturer of the aircraft for safe operation.

What is the role of the air traffic controller in the fuel drain?

The primary goal of the air traffic controller is to ensure safety by organizing the flow of traffic all To enable aviation participants. His duties also include providing information and supporting the pilots.

In an emergency, his work is limited to providing the crew with the best possible support.
In the event of a quick fuel discharge, the air traffic controller must provide the aircraft concerned with the best possible support and enable a safe remaining flight and a safe landing. His main task is also to ensure a safe distance between the person concerned and other aircraft.

How does a quick fuel dump work?

The crew alone decides what to do. Therefore, the air traffic controller only receives the message that a rapid fuel discharge is to take place.

If a pilot reports an emergency to the air traffic controller, the latter has the minimum requirements listed there in the event of a rapid fuel drain announced by the pilot, as far as he canto meet.

In individual cases, the controller identifies a suitable airspace that has the lowest possible volume of traffic and is as far away from large cities as possible. This airspace must be large enough that the pilot can safely perform all necessary flight maneuvers. The kerosene must be drained at a height of at least 1,800 meters (6,000 feet). As a rule, however, this takes place at greater heights between 4 and 8 kilometers. In addition, the airspace must remain free of passing traffic during the deflation and for 15 minutes thereafter.

The rules of the International Civil Aviation Organization (ICAO) apply to national air traffic control such as DFS Deutsche Flugsicherung GmbH and the pilots. The Federal Republic of Germany is determined to comply with the internationally applicable regulations of the ICAO, stipulated in document Doc 4444 "Procedures for Air Navigation Services - Air Traffic Management".

Are there clearly defined air spaces for fuel drains?

There are no fixed air spaces for fuel drains, rather it is an individual decision in each individual case. Emergency situations that require the kerosene to be drained usually occur immediately after take-off. In most cases, there is therefore a physical proximity to the departure airport.

What is the environmental impact of fuel dumping?

The Federal Environment Agency (UBA) has examined the effects of rapid fuel drains on people and the environment and published a corresponding report. You can find the report to read on the website of the Federal Environment Agency.

How is maintenance and repair carried out?

The maintenance of commercial aircraft is subject to strict technical and official requirements, which are aimed at planning the maintenance and repair of the aircraft in good time, both in terms of flight safety and in terms of economic operation, so that the probability of abnormal events (e.g. a landing gear failure and in the consequence of an emergency fuel discharge) is minimized. Due to the (European) aviation law provisions, the aviation companies and their maintenance companies are obliged to establish and maintain appropriate safety and / or quality management systems. They are subject to the supervision of the responsible national aviation authorities - in Germany the LBA.

How is compliance with maintenance and servicing monitored?

The German and EU aviation companies and maintenance companies must ensure compliance with the requirements for maintenance and servicing. They are monitored within the framework of the necessary official approvals by the competent authorities of the member states and the European Aviation Safety Agency EASA (maintenance companies with EU approval in third countries).

An essential aspect of safety management, both in the development of aircraft types and in ensuring airworthiness, is the continuous evaluation of events that have been identified during the operation of the aircraft. The above-mentioned risk analysis is continuously supplemented by the manufacturers based on the incoming event reports from the operation of the aircraft. The knowledge gained in this way is used, among other things, in the ongoing improvement of maintenance and repair measures, again in cooperation with the aviation companies and the responsible licensing authorities, which are then passed on to the airline companies and maintenance companies as part of regular revisions of the requirements for maintenance and servicing Aircraft are implemented.

This control and improvement cycle is already firmly established in the aviation technology system and, in particular, as already stated, is intended to minimize the likelihood of emergency procedures (such as fuel dumping) occurring as far as possible. However, there is always a "residual risk", so that the occurrence of events in individual cases cannot be completely ruled out.

Does fuel dumping have to be reported?

Fuel dumping is a reportable event that is documented and analyzed in a database. In Germany, reports of fuel dumping are received by the LBA (for German aircraft) and by the air traffic control organizations at the Federal Air Traffic Control Authority (BAF) for all aircraft flying in Germany.

The pilot in charge is obliged to report such an event to the LBA primarily via his "organization" (for example, the aviation company).

Due to the radio contact between the air traffic controller and the pilot during a flight, the air traffic controller is also informed in advance and clears the intended area for fuel dumping. Regardless of the flight crew, the air traffic controller reports the incident to the competent authority, in Germany to the BAF, which redundantly forwards the reports from the air navigation service providers to the LBA.

How often is fuel dumping reported?

For example, a total of 26 cases of fuel dumping over the Federal Republic of Germany were reported in 2017. On the other hand, there are over a million take-offs in commercial air traffic at all major German airports (source: Federal Statistical Office, Fachserie 8, Reihe 6.1).

Do foreign airlines have to submit a report?

Foreign airlines / pilots are not obliged to report events such as fuel dumping to the LBA, as the LBA is not their competent approval and supervisory authority. However, this does not release the airlines from informing their responsible aviation authorities in accordance with the applicable legal provisions.

The LBA is therefore only indirectly involved in fuel dumping by foreign airlines in Germany. However, the recording is guaranteed by the direct contact of the pilots with the DFS. For this reason, reports on these events are only sent from the DFS via the BAF to the LBA.

What are the legal bases for submitting event reports?

In addition to the relevant special implementing regulations based on Regulation (EU) 2018/1139 (since September 11, 2018), Regulation (EU) No. 376/2014 (reporting, analysis and follow-up of events) and Implementing Regulation (EU) 2015/1018, which relates to a reporting obligation and lists both the group of people who are obliged to report and the events to be reported. In addition, the EU member states are obliged to receive and evaluate voluntary incident reports.

In Germany, the LBA was named as the agency for reporting events. For the first time, all incoming technical and flight operations incident reports are recorded, analyzed and, if necessary, followed up at a central point.

At this point, the LBA also works closely with DFS Deutsche Flugsicherung GmbH and the BAF.
Further information on the submission of event reports can be found on the Internet at https://www.lba.de/DE/Betrieb/Ereignismmeldung/Ereignismommunikations_node.html.

It should be emphasized that reports on incidents that are submitted on the basis of Regulation (EU) No. 376/2014 enjoy special protection in accordance with Article 16 of this Regulation and, in principle, may only be used to improve air traffic safety.

What about military flights?

For military flights in German airspace, the same rules apply as for civil aircraft. The close civil-military integration results in a need and situation-dependent division of the control of military aircraft between the local air traffic control units at the military airfields, the tactical control service units and the DFS.

If the pilot of a military aircraft declares an air emergency during the flight, military agencies and civil air traffic control coordinate the further action.


A fuel discharge is always an emergency procedure to avoid endangering the life and limb of the passengers and / or the flight crew on board the aircraft, which is only used very rarely, based on the number of flights over Germany. There is an extensive international and European set of rules for implementation and application. All cases are recorded and evaluated centrally in Germany. The procedures are designed in such a way that, on the one hand, safety in aviation is maintained and, on the other hand, the effects on the ground are reduced to a minimum.