Lufthansa is set to change its take-off procedure for all departures outside Germany, thereby implementing worldwide standards. As of 1 June 2013, the altitudes for using the climb thrust and for further accelerating Lufthansa aircraft that are taking off will change from 1,500 feet (approx. 457 metres) to 1,000 feet (approx. 305 metres). This procedure is standard at most German and international airports and is already used by many airlines as it leads to lower fuel consumption and a reduction in CO2 emissions. At Frankfurt Airport, many airlines today are already benefiting from this take-off procedure.
Before it is introduced at German airports, the effects of the more level take-off will first be examined in a sound measurement test phase. Lufthansa expects the effects to be positive overall, as aircraft will be in a low-resistance, and therefore less noisy, configuration at an earlier stage. This assumption will be tested at Frankfurt Airport in a trial run from 1 July until 30 September 2013 by measuring selected flights, while all other flights will take off as before for the purpose of comparison. The sound measurements will be evaluated in co-ordination with the independent Airport and Region Forum (“Forum Flughafen und Region”). A scientific study was previously commissioned at the German Aerospace Center, which predicted only minimal sound changes as a result of the new take-off procedure.
The objective of this step-by-step process is to transparently record and evaluate reliable measurement data for noise levels during the new procedure. Once the data has been analysed, it will be decided whether the 1000-foot acceleration will be introduced at German airports.
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 expects that changing the procedure in Frankfurt alone would save around 2,200 tonnes of fuel per year. This would mean around 7,000 tonnes fewer CO2 emissions. The benefit for the environment is much greater worldwide: approx. 6,000 tonnes less kerosene, or around 18,000 tonnes less CO2.
A reduction in the acceleration altitude from 1,500 to 1,000 feet is permitted under ICAO regulations and is already standard practice at many airlines. Any procedural changes to an airline’s operations manual must be notified to the national supervisory authority. For German airlines, this is the German Federal Aviation Authority (LBA). The LBA and the German Federal Ministry of Transport, Building and Urban Development have already granted Lufthansa permission to change the procedure.