The Royal New Zealand Air Force says there is no way it can avoid low level flying in built-up areas.
Four Iroquois helicopters have been practising tactical low flying operations above Wellington between sunset and midnight.
Some flew so low they shook houses.
The RNZAF says it is a Government requirement that the air force practise low level flying in a built-up area.
Spokesperson Kavae Tamariki says the air force tries to minimise the noise, but it was particularly loud on Sunday night because the sound was reverberating off low cloud.