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C U. K.
Croydon is an international air port of U. K.
Croydon had the first customs in the UK (passengers were weighed individually with their baggage and if they were over a certain weight, they had to pay extra — this has been an inspiration for budget airlines since). It had the first charter flight. It had the first departure board (essentially a wall of clocks, which quickly became confusing and was ditched after about two years). It also had the first airport hotel in the world, now the Hallmark Hotel Croydon Aerodrome. And it was the spiritual home of Amy Johnson — the first woman to fly solo from England to Australia (she took off from Croydon in May 1930).
On a darker note, Croydon was the first airport to have a major civilian crash, when an Imperial Airways de Havilland DH.34 came down in Purley on Christmas Eve 1924, killing eight. A stranger, but equally dark, event occurred on 4 July 1928, when wealthy businessman Alfred Loewenstein left Croydon, bound for Brussels, but then stepped out of the plane while it was over the Channel. Whether this was the first suicide by plane, or a tragic accident, isn't known.