GRANDE PRAIRIE, AB -- A pilot who crashed and died near a BC airport in November was texting and making calls on his cellphone during his flight, an investigation revealed.

The report published by the Transportation Safety Board of Canada (TSB) said the lone occupant of the Cessna 185E was talking on his phone five times and replied three times to text messages, totalling 28 minutes, during a flight from Peace River, Alta., to Fort St. John, BC, about 260 km west.

Mark Crozier, 29, left the Peace River Airport just after 5 p.m. on Nov. 31, 2011.

The last contact between the pilot and the FSJ Flight Service Station was at 6:13 p.m

The last radar contact with the plane was at 6:17 p.m., before it crashed into a tree and plunged into the snow-covered ground 22 kilometres east of the airport. Crozier died on the scene.

The report found a drastic change in altitude throughout the flight, the plane dipping as low as 3,500 feet and as high as 4,600 feet, with each descent beginning when the pilot checked his phone.

The investigation report goes into great detail of the events of the flight, but couldn't reveal the cause of the crash because the aircraft didn't have a black box, cockpit voice recorder or autopilot, as it is not required for such a small plane. The pilot was not on his phone for the last 11 minutes of the flight.

The cellphone activity is acknowledged as a possible factor to the crash but not necessarily the cause.

Mike Tomm, operational investigator for the TSB, said cellphone use while flying is not a widespread problem.

"It's something we haven't seen a lot of, but like any particular phenomenon, once it comes up, certainly we will address it," he said.

Also, the report said the pilot had been on the phone throughout his seven hours of flying that day, and was in contact with 12 different people on 17 occasions.

Along with using a cellphone, Crozier was flying at night, which could cause a "black-hole effect" - meaning the lack of a moonlit sky or any visual cues from the ground can affect depth perception.

"At nighttime...there's more of a reliance on instruments," Tomm said, adding it's likely the pilot could have seen the lights of the airport and would have been able to see the city lights of Fort. St. John.

The report could not determine if Crozier had any nighttime flight experience.

As a result of the crash, Trek Aerial Survey, the company Crozier was working for, has banned flights after sunset and banned the use of cellphones during flight unless for an emergency.