Jet2 flight LS775 had left Edinburgh Airport around 8.30am bound for Alicante, but signalled an emergency situation around an hour into the flight.
It diverted to London Gatwick, where it landed safely just after 10.00am.
Jet2 has confirmed that a medical emergency caused the detour.
The airline carried 5.5m passengers on over 36,000 flights in 2013, an increase of 15.5 per cent on the previous year.
Jet2 is based at Leeds-Bradford Airport, and flies to 17 destinations from Edinburgh, including Salzburg in Austria, Faro in Portugal, Hungarian capital Budapest and Croatian cities Dubrovnik and Split.
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