Investigators assess fatal Qld plane site

Investigators will spend days at the site of a Queensland plane crash, which killed an instructor and his student when their light aircraft plunged into a turf farm.

A mayday call was made shortly before the single-engine Diamond DA-40 spiralled from the sky and crashed nose-first into the farm at Allenview, south of Brisbane, on Tuesday morning.

The aircraft had taken off from Archerfield and was in the air for about 40 minutes before the crash.

Australian Transport Safety Bureau investigators from Brisbane and Canberra are expected to spend days examining evidence, talking to witnesses and trying to recover flight data.

The Civil Aviation Safety Authority said it was too early to speculate about causes.

The ATSB will prepare a report which is expected to take months to complete.