After the Doctor had been rescued by the Mentiads he asked them how the Captain arrived on their planet Zanak. The leader of the Mentiads respond with: Legends speaks of a silver ship falling from the sky one night with a mighty crash like thunder. The Captain was one of the few survivors.
Couldn’t this easily describe how Oceanic Flight 815 arrived on the island? How many coincidences do you have to witness before you start to believe. If you are a doubting Thomas watch the Key to Time and the Face of Evil to see that all that I tell you is true.