In the twelve months since August 2013, Lufthansa has been carrying out trials on the noise emissions produced by the 1,000 foot acceleration procedure. In the new procedure, the aircraft leaving the west runway at Frankfurt Airport reduced the altitude for acceleration and additional thrust from 1,500 feet (approx. 457 metres) to 1,000 feet (approx. 305 metres) where allowed by local restrictions on the departure flight path.
During the world’s biggest examination of take-off noise, the measuring stations recorded over 70,000 Lufthansa take-offs. This represents more than half of all the airline’s departures in Frankfurt. The data were analysed by Forum Flughafen and the local region, which could not identify any significant changes in noise emissions as a result of the modified take-off procedure.
The measurements support the existing detailed calculations carried out as part of a scientific study by Lufthansa, TU Berlin and the German Aerospace Center. On this basis Lufthansa has now decided to introduce the modified take-off procedure nationwide as of today and so to implement this established global standard worldwide. Many other airlines have been using this take-off procedure for years, making it common practice already at most German and international airports, because the related fuel consumption and carbon emissions are much lower.
The change in the acceleration altitude to 1,000 feet took place in accordance with the standards laid down by the International Civil Aviation Organisation (ICAO). Lufthansa obtained permission to modify its procedure from the German Federal Aviation Authority and the Federal Ministry of Transport and Digital Infrastructure (BMVI) some time ago.
What does 1000-foot acceleration mean?
After an aircraft takes off from the runway, it usually ascends at a constant speed with the flaps extended until it reaches a certain altitude. Modern aircraft generally do not use the maximum thrust available at this point, but rather a reduced level of take-off thrust. When the aircraft reaches an initial target altitude, the engines’ thrust switches to climb thrust. As the aircraft continues to take off, it has to accelerate so that the flaps can be retracted and it can climb to its cruising altitude at a higher speed. The altitude at which the speed increase begins is called the acceleration altitude.
By changing these two altitudes, the wind resistance decreases when the flaps are retracted, thus lowering fuel consumption. Lufthansa believes that changing the procedure in Germany alone would save around 3,000 tonnes of fuel per year. This would mean around 10,000 tonnes fewer CO2 emissions. The benefit for the environment is much greater worldwide: approx. 6,000 tonnes less kerosene, or around 19,000 tonnes less CO2.