Air France's Flight 358 crashed on August 2, 2005 when it attempted to land during a serious thunderstorm at Toronto's Pearson International Airport. The plane skidded off the runway into a ravine and burst into flames.

Amazingly, all of the 309 passengers and crew managed to escape the burning wreckage. The crash left 43 people injured.

On Nov. 16, Canada's Transport Safety Board released a preliminary report based on an examination of the flight-data recorders as well as the aircraft wreckage.

While investigators have found some answers, there are still many outstanding questions. Following is a summary of what is known to date.

Was there something wrong with the aircraft?

The Transportation Safety Board of Canada is leading the investigation into the Air France crash at Toronto's Pearson Airport.

A preliminary report published November 16 stated that there did not appear to be any problems with the Airbus A340-300 that crashed and burst into flames after skidding off the runway.

"To date, investigators have not found significant anomalies of the aircraft systems," the report said.

Flight 358, which had 297 passengers and 12 crew on board, also had plenty of fuel, ending speculation that it might have run dry.

The agency is now looking at weather or pilot error as possible causes of the Aug.2 accident, which left 43 people injured.

What about the weather?

At noon on Aug. 2, airport officials issued a Red Alert because of severe weather in the Toronto area. That prevented most flights from taking off during the afternoon.

Incoming flights were still permitted to land if the pilot was confident that conditions allowed it.

Among them was Air France Flight 358 flying in from Paris. It left Charles De Gaulle Airport at 1:32 p.m. Paris time and was due to land in Toronto at 3:35 p.m. ET.

The plane landed in a severe thunderstorm, which included torrential downpours and very strong winds. One passenger remarked that the winds were so strong, the trees were bent over almost parallel to the ground.

Investigators have still not ruled out weather as a possible contributor in the crash.

Did lightning strike the plane?

On Aug. 5, Transportation Safety Board investigator Real Levasseur told a news conference that there was no evidence that lightning struck the plane during landing.

However, some eyewitness reports claimed that lightning appeared to hit the plane during its final descent.

Aviation expert Joseph D'Cruz told reporters that lightning by itself would not usually pose a risk for an Airbus A340-300.

"The aircraft has a metal shell which protects the passengers, and, secondly, the aircraft is on rubber tires," he said. "So lightning by and of itself is not likely to be a factor on its own. Lightning in combination with something else could have been a problem."

When did the fire break out?

Airport officials say emergency response teams were on site within 52 seconds. By that time, approximately three-quarters of the passengers had been evacuated down the chutes and into a nearby field.

The fire was rapidly spreading at that time and airport fire chief Mike Figiola said he could feel the intensity of the heat 50 metres from the aircraft.

Figiola said the plane was emptied of passengers and crew within two minutes. The rescue operation then turned into the job of putting out the fire.

Had fire broken out inside the aircraft, the passengers would have had only about 30 seconds to get out before becoming overcome by smoke and fumes.

However, flames on the exterior did increase the possibility of an explosion, but thankfully that didn't happen.

Fire officials say it took about four hours to get the fire under control, but it was still smouldering 16 hours later. The plane had broken into three pieces.

What about the pilot's role?

It is the pilot's responsibility to bring passengers to their destination as safely as possible and the decision to land in less than ideal conditions lies with the pilot.

According to Don Enns of the Canada Transport Safety Board:

"Ultimately the pilot is flying this airplane. If the conditions are suitable or he deems them suitable he can proceed to land. Prior to that he's given instructions by ATC (Air Traffic Control)."

On Aug.5, Transport Safety Board investigator Real Levasseur said that the aircraft landed 500 metres further down the runway from where a similar passenger jet would normally touch down.

Levasseur said all four of the plane's thrust reversers were operating correctly when the plane landed. Thrust reversers help slow the plane after landing. The plane slid off the runway at 150 km per hour.

Investigators are still analyzing whether pilot error was a factor in the crash.

Why did it take so long to find out about casualties?

There was a lot of confusion after the crash. Some of the 297 passengers and even the pilot made their way to the nearby Highway 401 where they flagged down drivers and got rides either back to the airport or out of the area.

Others were taken to a nearby hotel or to the airport. Several passengers were angry that they were forced to go through customs.

With passengers scattered in different locations and the plane still in flames, it was difficult to get a quick and accurate tally of passengers who had escaped the burning wreckage.

Federal Transport Minister Jean Lapierre was travelling to Iqaluit at the time of the accident.

He said he was initially told by Defence Department officials that 200 people had died in the crash. He didn't receive the correct information until he was on the ground in Nunavut.

It was at least two hours after the crash before word came out that nobody had died and there were no serious injuries.

Why are flight data recorders so important?

There are two types of recorder (usually referred to as 'black boxes') on planes. The cockpit voice recorder tapes cockpit conversations, both among the crew and between the crew and the control tower.

The flight data recorder captures a variety of information, including: time of accident, pressure altitude, airspeed, vertical acceleration, magnetic heading, fuel flow and control-wheel position.

Both recorders were recovered the day after the accident and shipped to France for further analysis.

The devices are designed to withstand the impact of a crash and searing heat that can exceed 1,000 degrees Celsius in a plane crash and fire.

Although referred to as 'black boxes,' the devices are, in fact, orange.