It is certainly the sound of speed brakes being extended. The sound is very caracteristic and much louder than any other sound produced by the aircraft.
It can be heard on the ground while the aircraft is as high as 20000 ft.
The arrival routes for EDDH are coded -HAM-LBE-FAP but the actual distance flown is a direct to final, much shorter. So many pilots end up being much to high and have to use the speed brakes.
I flew the A320 for years, when my parents moved to a town 30 NM south of EDDH. When I sat in their garten for the first time I was nearly shocked what an extreme amount of noise those speedbrakes produce. Nearly 2/3 of all arriving Airbus end up deploying them more or less over our house, and while no aircraft noise is heard inside the house normally the sound of A320 speedbrakes being extended is clearly noticable.
Last edited by safelife; 6th Sep 2012 at 21:17.