EIA meaning in Airport Code ?

Eia or Eye was an early Medieval manor in the parish of Westminster, Middlesex and is now a part of Central London. It was about one mile west of the Palace of Westminster/Whitehall, about 2 miles west-south-west of the walled City of London, and about half a mile north of the River Thames. A smaller sub-manor called Ebury or Eybury, containing the hamlet Eye Cross, was originally part of the manor (and are derivations in name). Ebury and a corruption of it, Avery, appear as modern streets and other places.

Today, the area of the manor includes much of Hyde Park (which dates from 1536), the grounds of Buckingham Palace (1703), Belgravia, a country road known later as Park Lane and most parts of Mayfair, Pimlico, and Knightsbridge. (Together these form much of the western part of the SW1 postcode area),

The name Eia is believed to have originated as a Latinisation of the Anglo-Saxon word īeg, which means "island", in reference to a rise along a stream/marsh, and from maps seems to refer to a former, perhaps only discernible after heavy rains, island above one which surrounded Westminster Abbey, Thorney Island, drained and formed by the River Tyburn.