I know these occur far more frequently than we think but how many would you expect in the average day (no extreme weather) at somewhere busy like Gatwick or Heathrow?
Over the last few years, go-arounds at Heathrow have averaged around 550 p.a.
It's not unknown to see two or more consecutive GAs (there were 4 in a row Wednesday before last). Equally, there can be long periods without one - Heathrow rarely has "average" days.
The conventional wisdom is that fewer GAs than at present would mean that ATC wasn't trying hard enough.
