The Transportation Safety Board of Canada says the pilot's decision to continue an unstable approach was the key factor in the plane crash that killed Jean Lapierre and his family in Quebec's Magdalen Islands almost two years ago.
The report says the loss of control occurred on the Mitsubishi MU-2B-60 aircraft "when the pilot rapidly added full power at low airspeed while at low altitude, which caused a power-induced upset and resulted in the aircraft rolling sharply to the right and descending rapidly."
While pilot Pascal Gosselin, who both owned and flew the plane, attempted to recover, there was insufficient altitude before the aircraft struck the ground.
The plane broke apart before coming to rest near a cluster of homes in the Magdalen Islands.
The report found Gosselin was trying to deal with too many tasks when he lost control as the plane was too high and too fast, with little time to react.
"The pilot was in a very complex situation, in an unstable situation," said TSB investigations director Natacha Van Themsche.
"It's a mix of factors. The pilot, you have to understand, that most other pilots probably would have taken the same actions."
Unstable approaches is one of the issues on the TSB's watch list.
The findings showed there weren't any discussions about a contingency plan or including aborting the landing and performing a go-around.
Investigators did not find any mechanical deficiencies with the aircraft.
Lapierre, his wife Nicole Beaulieu, his sister Martine Lapierre, and brothers Marc Lapierre and Louis Lapierre, all died in the crash on March 29, 2016. Lapierre was a political commentator and former Liberal federal cabinet minister.
Gosselin and crew member Fabrice Labourel also died when the plane went down.
The Lapierres were on their way to the Magdalen Islands to plan the funeral of the family patriarch, Raymond Lapierre, who had died a day earlier.
Quebec coroner Dr. Martin Clavet said the deaths were accidental and avoidable. His reports into all seven deaths were also released on Wednesday, shortly after the TSB's investigation.
The Lapierre family released a statement in French today thanking TSB investigators, the coroner and all who worked to shed light on the accident.
They said while the reports stir up difficult memories, they are a necessary part of the family's grieving process.
Not sufficiently practised?
The TSB also found that while Gosselin had the number of required hours to fly the aircraft, he had only flown that aircraft for a total of four hours in the month prior to the crash.
The report found it was unlikely that his "flight skills and procedures were sufficiently practised to ensure his proficiency as the pilot-in-command for single-pilot operation on the MU-2B for the conditions experienced during the occurrence flight."
"It may not have allowed him to practise his skills and procedures enough," said Fox.
The findings also show "one of the passenger-pilots who would typically accompany the pilot were available" for the flight.
It said that Labourel, the passenger-pilot who was contacted and agreed to go on the flight, had never flown with Gosselin before.
'Suitable, not ideal' weather
On the morning the flight took off from the Saint-Hubert airport, just south of Montreal, there were reports of fog on the islands, which are in the Gulf of St. Lawrence, close to P.E.I. Several commercial airlines cancelled flights because of the weather.
A weather report warned of limited visibility and a low cloud ceiling with the potential for icing in the air.
After the crash, some pilots and aviation experts questioned whether the twin-engine turboprop should have taken off in the first place, and whether Gosselin should have flown to an airport with better weather conditions.
The findings, however, did not point to weather conditions as a contributing factor to the fatal crash.
"The conditions under which the pilot operated were suitable, not ideal — but it was suitable and legal to take flight that day," said TSB chair Kathy Fox.
Investigators also found that turbulence and icing did not play a role.
Flight recorder provided invaluable information
The TSB said its probe was aided by the lightweight recorder installed by the pilot that provided cockpit audio and acceleration and GPS data — even though the data recorder wasn't required.
After the crash, investigators were able to recover the recorder, which remained intact.
Fox said the TSB often runs into a lack of information in such crashes where there are no witnesses or survivors and the plane is too badly damaged.
"Without it we might never have learned what happened," she said