General FAQs

1. What is a decibel?
2. What does the ‘A’ in the dBA unit mean?
3. What is Leq?
4. If the number of aircraft noise events is doubled, the noise level only increases by 3 dBA, why?
5. What do aircraft noise exposure contours show?
6. How are noise contours produced?
7. Are there other noise models available, and are they the same as ANCON?
8. Why is a 57 dBA contour considered important?
9. I live outside the published 57 dBA contour and I am overflown; I can hear aircraft and it annoys me - how is this possible?
10. I live outside the published 57 dBA contour, but when I use a sound level meter to measure aircraft noise outside my house, the reading is more than 57 dBA - how is this possible?
11. What is Lden?
12. How do I make a complaint about aircraft noise?
13. What are the ‘Chapter 2’ and ‘Chapter 3’ aircraft noise classifications?
14. What is the new "Chapter 4" noise standard?
15. How do I purchase the latest annual contour reports for Heathrow, Gatwick and Stansted?
16. How do I purchase other reports produced by ERCD?