Aircraft
Low or heavily loaded aircraft, including military transports, can produce a startling low roar or bang.
How to tell
- Sound moves across the sky rather than staying put
- Builds and fades over several seconds
- Aircraft visible or audible immediately before
When it usually happens
Any time.
Heard one just now?
Report it and we will tell you what it most likely was. More reports from different directions make it far easier to pin down.
Report what you heard