A Transportation Safety Board report released Monday said the crash near the airport in Fort St. John, B.C., last November could have been partly caused because the pilot wasn't concentrating on his flying.
The TSB report said the pilot received three text messages and spent 28 minutes on his cell phone during what would have been a 65-minute flight from Peace River, Alta., to Fort St. John, B.C.
The pilot received his last text message 11 minutes before the crash.
"The aircraft had experienced several large altitude deviations while the pilot was using his cellphone," the report stated. "This distraction was prevalent throughout the flight and in conjunction with the night conditions encountered, may have contributed to the (crash)."
A graph in the report shows the altitude on the Cessna 185 E, operated by Treck Aerial Surveys, dipped from a low of 3,500 feet to a high of 4,600 feet three times during the flight.
"Cell phone use can distract operators from essential operation tasks.
"There have been no comprehensive studies regarding the use of cell phones as a distraction in an aviation context. The phenomenon has, however, been extensively studied in the automotive sector."
Using a cell phone while driving is illegal in every province and territory except Nunavut.
The report found there were also other pressures against the pilot including that he needed to be back to the Fort St. John airport before nightfall.
The commercial pilot was operating on night visual flight rules, but it was dark as he neared the Fort St. John airport.
The company the pilot was working for, Treck Aerial Survey's — which provides aircraft and equipment for aerial surveillance and photography — is limited to vision flight rules during the day.
The report said there was no indication of an aircraft system malfunction or that the pilot was unwell. There were no drastic changes in the aircraft's flight path and no emergency calls from the pilot to indicate that there was an inflight emergency.
Instead, the report said the pilot may have lost situational awareness, known as the "black-hole effect."
"A black-hole approach typically occurs during a visual approach conducted on a moonless or overcast night over water or over dark, featureless terrain where the only visual stimuli are lights on or near the airport."
Without visual reference, the report said, the pilot's depth perception may be off, causing the illusion that the airport is closer than it actually is.
The plane's wing clipped a tree and then slammed into the ground about 20 kilometres from the airport, killing the only person aboard.
The TSB has recommended that pilots limited to visual flight rules be restricted to flying during the day and that cell phone use by pilots during a flight be prohibited unless there's an emergency.
"Pilots who engage in non-essential text and voice cell phone communications while conduction flight operations may be distracted from flying the aircraft, placing crew and passengers at risk," the report concluded.