As for the "which country", we have been told is was during "taking off and landing at an RAF base" - that leaves the UK, UK, UK, UK, UK, Cyprus, UK, UK, UK, UK, UK, UK, Malvinas, UK, UK, UK, UK, UK, Gibraltar, UK, UK, UK, UK, UK, .... Did I mention Malta, perhaps, Ascension, and of course the UK?
I agree "500 feet" needs qualification - but why would the title of this thread be what it is? In fact, the opening post mentions "height" several times but never an "altitude".