A PILOT involved in a fatal plane crash on the Isle of Bute which claimed the life of his only passenger was not up to date in his training, investigators have found.

A report by the Air Accident Investigation Branch (AAIB) said there was no evidence that the 53-year-old pilot, who has not been named, had completed the additional training necessary to fly the single-engined Sportcruiser G-EWZZ.

The light aircraft crashed moments after take-off from runway 27 at Bute Airstrip, near Kinglass, at 2.40pm on August 9 last year.

According to the pilot, the engine had cut out and the aircraft was unable to climb, leading him to attempt an emergency landing. Instead the plane struck the ground and overturned before coming to rest upside down in a ditch and catching fire.

Both the pilot and his passenger, 63-year-old Thomas McGowan, from Stonehouse in Lanarkshire, suffered severe burns and were airlifted to hospital in Glasgow.

Mr McGowan later died from his injuries.

The friends had flown from Strathaven to Bute for a lunch with other pilots, and were the last to take off.

The AAIB report into the incident noted that the pilot had obtained his National Private Pilot's License in April 2010 and accumulated 100 flying hours on the Sportcruiser prior to the crash.

However, investigators said that while his logbook showed he had "met the ongoing validity requirements" to pilot a simple single-engine Aeroplane (SSEA), this rating "requires additional differences in training to operate aircraft with variable pitch propellers", which the Sportscruiser had been fitted with.

The report continued: "Such training is recorded by an entry and signature in the pilot's logbook by a suitably qualified instructor; there was no record that this additional training had been completed."

Accident investigators also found that the home-built aircraft had been "fitted with unrecorded modifications, which meant that it was not in compliance with its Permit to Fly".

In particular, the modifications meant the aircraft was "likely to have been over its approved [weight] of 600kg", although investigators said it was unlikely that this alone had inhibited its ability to climb.

The pilot had also disabled the stall warning system due to a number of "spurious warnings".

However, investigators said the level of fire damage to the aircraft meant it was impossible to determine whether the engine had lost power and caused the crash.

The AAIB has issued a number of safety improvement in relation to on-board parachute systems for this type of aircraft.