Civil Aviation Authority investigators are gathering evidence and will interview pilot Robin Langslow to determine how his plane crashed on Tuesday, leaving him in intensive care and his passenger in a critical condition.
Mr Langslow was trying to land a Cresco topdressing plane on his Otane farm when it crashed about 6am.
Mr Langslow and his passenger, both believed to be in their 60s, were trapped in the cockpit and received serious and critical injuries before they were cut from the wreckage by emergency services.
A CAA spokesman said air-crash investigators were gathering information but he was reluctant to comment further to protect the integrity of the case.
"The most important thing will be to try [to] find if there are any safety learnings to take away from this crash, and if there are and there is something wrong with the aircraft we need to know as soon as possible to get the message out to the manufacturer."
