Our glossary contains frequently used terms and acronyms together with their explanations.

Departure procedures

For some time now, a flight procedure has been used on selected departure routes at Frankfurt Airport that can reduce the noise below the departure route on the ground. In this case, the aircraft are prescribed a maximum airspeed of 220 knots (410 km/h) for the first six nautical miles (approximately 11 km). By limiting the speed, the excess engine thrust produced during take-off goes towards the altitude instead of speed. Although the aircraft climbs more steeply, it becomes slower in terms of the geography on the ground, which means that a reduction in noise may be offset by a longer noise impact on the population. Slower speed does, however, positively affect adherence to turns. 

You will find more information about additional noise-abatement measures from the Alliance for Frankfurt Airport.

Altitude and compliance with the departure route
People living near airports often complain about aircraft flying too low. It is, however, almost impossible to estimate an aircraft's altitude from the ground. This is due to the way human perception works. The human eye uses, among other things, reference objects to estimate distances – such as the height of a person or a house. When looking at objects in the sky, there are no such reference parameters. Without additional information it is virtually impossible to estimate the actual altitude of an aircraft with the bare eye.

As a rule, air traffic departs following defined procedures. These may or may not include altitude instructions. Up to a certain altitude, compliance with defined departure routes is compulsory for DFS controllers to keep the sky safe. Therefore, controllers do not deviate from these routes unless absolutely necessary, for example in case of a thunderstorm or any problems.

Individual deviations from the ideal departure route are inevitable to a certain extent, such as due to the weather or aircraft performance. Therefore, a possible framework for deviations from the ideal path is determined based on international ICAO standards. These tolerance areas are attributable to different types of aircraft and navigation methods. If the cockpit crew is found to have made a mistake in terms of compliance with a departure procedure or if the pilot independently and for no reason deviates from the departure procedure, the Federal Supervisory Authority for Air Navigation Services (BAF) will initiate legal proceedings against the pilot-in-command.

Individual clearances
At the instruction of the air traffic controller, pilots may leave a departure route and initiate a direct flight once they have reached a certain altitude. Formally speaking, the clearance for a direct flight may be issued as early as when the minimum safe level or the minimum radar vectoring altitude has been reached. Exceptions to this are flights that have to turn earlier due to safety reasons. According to the internal policy at DFS, jets are not to be cleared for turning below 5,000 ft (approximately 1,500 m) due to noise abatement reasons. At some airports, this level has been raised even higher due to noise abatement, local conditions and in consultation with the local Noise Abatement Commission. By issuing individual clearances, DFS is adhering to its statutory obligation to handle air traffic safely, orderly and expeditiously - as stipulated in the German Aviation Act. Furthermore, direct flights reduce fuel consumption and CO2 emissions.