Complex sentence: The boat surfaced at position at around 10:50 am, and was immediately detected by the radar of a second 269 Squadron Hudson, flown by Squadron Leader James Thompson, that was paroling the area after being summoned by radio by Mitchell.
Split into simpler sentences: The boat surfaced at position at around 10:50 am, and was immediately detected by the radar of a second 269 Squadron Hudson. Flown by Squadron Leader James Thompson, it was patroling the area after being summoned by radio by Mitchell.