Does anyone know why EasyJet uses U2 as the prefix for flight numbers? Other airlines have more logical prefixes. Eg. KL -> KLM, AZ -> Alitalia, BA-> British Airways, etc. Even though they do not always match the airline name exactly, they do mimic the name.
EZY(EasyJet UK) code and EZS(EasyJet Switzerland)are the ICAO codes, whereas U2 is the code generated by IATA.So the reason why they use the code U2 is because this is the code IATA generated for them when they applied for an IATA code.You can look at the document below that has to be submitted to IATA in order to get the code.
EasyJet Airline Company Limited (UK Based) - (IATA code : U2 ; ICAO code EZY ; Callsign : Easy ) EasyJet Switzerland SA ( IATA code : DS ; ICAO code : EZS ; Callsign : TOPSWISS )
ICAO codes are used for operational purposes like flight planning,ATC etc whereas IATA codes like U2 are generally used in timetables, reservation systems, departure/arrival information etc. In other words information that is meant for the general public.
Easyjet got their IATA code fairly late on, and as such could not use EZ (which was in use by Sun Air), so they were randomly issued their IATA code of U2.
They do have the three letter code of EZY, just as British Airways has BAW as well as BA.