Ground noise controls
Limiting the use of reverse thrust
Reverse thrust assists with braking once an aircraft has touched down. To minimise disturbance in areas adjacent to the aerodrome, pilots are requested to avoid the use of reverse thrust after landing, consistent with the safe operation of the aircraft, between 23:30 and 06:00.
Fixed Electrical Ground Power (FEGP)
Auxilliary power units (APUs) are small jet engines in the tail of an aircraft that are used to deliver electrical power and cabin conditioning while on the ground.
Through our Operational Safety Instructions (OSI) we specify conditions for APU usage in airport procedures to limit their use and supply alternative system for use whilst on the ground including fixed electrical ground power (ie we plug planes into the mains) and pre-conditioned Air (PCA). This seeks to limit the need to use the APU, which directly leads to a reduction in ground noise.
Currently at Heathrow, 90% of stands are fitted with electricity connections and 21% provide pre-conditioned air. If FEGP is not available airlines use ground power units to supply electrical power. These are diesel generation units and as part of our Operational Safety Instructions on ground noise, we set noise limits for them.
Turnaround and APU audits are carried out on a weekly basis covering the whole airport each month.
The timings and locations change each audit in order to ensure as true picture of usage as possible. Any non-compliance is dealt with directly with the airline.