A pilot killed in a plane crash alongside his passenger flew his aircraft into the ground after misreading his GPS, investigators say.

Pilot Andy Thompson, from England, and passenger John MacKinnon, from the Highlands, both died in the Perth and Kinross collision.

Their plane came down west of Abernyte during a flight between Inverness and Dundee on May 3 last year.

Mr Thompson was flying the aircraft south for an inspection which should have been carried out more than a month earlier, but there was no evidence that there were any problems with the plane.

The 37-year-old had asked the owner of the aircraft to join him on the flight but he was too busy and Mr MacKinnon, 53, joined him instead.

They left Inverness Airport at 10.30am heading towards Dundee and arrived on the outskirts of the city half an hour later.

The aircraft was cleared to land at around 11.10am but air traffic controllers became concerned when the plane then disappeared.

At 1.53pm, a search and rescue helicopter discovered the wreckage of the aircraft nearly eight miles west of the airport.

Air accident investigators concluded that the plane struck an area of dense heather before colliding with trees and breaking apart.

Experts from the Air Accident Investigation Bracnh (AAIB) reported: "The aircraft collided with high ground 6.7 nautical miles west of Dundee Airport whilst conducting an instrument approach.

"Evidence indicates that the pilot probably mistook the distances on his GPS, which were from NDB [a system used to navigate over long distances which can be affected by weather and mountainous terrain] as DME [a transponder-based radio navigation system] and commenced his descent too early.

"Anecdotal evidence suggests that mistaking GPS distance from the [Dundee] NBE with DME distance is a common error made by pilots."

Highlands and Islands Airports Limited (Hial) has taken a number of steps to prevent similar incidents in the future.

A spokesman for Hial added: "Our thoughts are very much with the family and friends of the two men who died in this accident.

"As the AAIB report indicates, the procedures in place at Dundee have been approved by UK and international regulators and were found to be fully operational at the time of the accident. Earlier arriving aircraft had not reported any problems.

"Nevertheless, given that safety is our paramount concern, we have been looking at ways to enhance the already robust safety procedures in place at Dundee Airport."

Mr Thompson was an experienced commercial pilot who flew Boeing 737s on a regular basis and had flown to Dundee many times.