HALIFAX -- Investigators from the Transportation Safety Board spent Monday sifting through the debris of a plane crash in Halifax and documenting the site where the Air Canada flight touched down short of a runway before skidding to a stop, sending 25 people on board to hospital.
But the safety agency has also used the accident to reinforce its calls for changes at Canadian airports to make approaches and landings safer.
"This kind of approach and landing accident is very much something that we pay very close attention to," said Mike Cunningham, the agency's regional manager of air investigations.
The board is in the early stages of its investigation into the crash of AC624 and it is highlighting the fact that approach-and-landing accidents have been on its watch list of issues that pose the greatest risk to the country's transportation system.
On Monday, investigators documented the site of Sunday's crash, identifying the components of the wreckage from where it touched down about 335 metres short of the runway to where it stopped skidding.
Cunningham said they have also had preliminary discussions with the flight crew and started interviewing passengers. The flight data recorder and cockpit voice recorder have been sent to the board's engineering branch in Ottawa and will undergo a preliminary analysis, he added.
Officials with the plane's French manufacturer, Airbus, were scheduled to arrive Monday to help with the investigation and removal of the plane.
Cunningham said when the plane touched down short of the runway it hit an antenna array, where the A320 Airbus lost its landing gear, and then slid another 335 metres down the runway on its belly before coming to a stop.
The 133 passengers and five crew members all survived the crash, but 25 people were taken to hospital, where most were treated and released.
In a statement released Monday evening, the safety board said the plane became airborne again after it first touched down, leaving an extensive debris field between the antenna and the start of the runway.
"The initial impact was significant and caused substantial damage to the aircraft," the board said.
It said the next steps in its investigation include surveying, examining and photographing the wreckage site, removing the aircraft to restore normal operations at the airport, gathering meteorological reports and collecting operational information from the plane.
In its 2014 watch list, the board repeated recommendations to improve runway standards, including lengthening runway end safety areas or installing engineering systems or structures to safely stop planes that overrun runways.
Cunningham said the crash displays some of the characteristics of approach-and-landing accidents on its watch list.
"The most important factor is the actual approach itself and understanding why the aircraft touched down as short of the runway as it did," he said in an interview.
"But it's linked to our watch list and the type of approach and landing excursion event that we pay particular attention to."
The board's watch list fact sheet quotes from the Flight Safety Foundation's 2013 report "Failure to Mitigate," which says that 3.5 to 4 per cent of aircraft approaches are unstable before landing. Of these, 97 per cent are continued to a landing, with only three per cent resulting in a go-around where the pilot aborts, says the foundation, an international non-profit organization that gives independent expert safety guidance to the aviation and aerospace industry.
From 2009 to 2013, Canadian-registered aircraft were involved in an average of 150 approach-and-landing accidents every year, of which six per cent were runway overrun accidents, the board says. Many of those accidents involve small aircraft so they don't generally draw as much attention.
This issue of approach-and-landing accidents has been included on the board's watch list since 2010. It says on its website that some progress has been made since then as some airports have improved runway surfaces and safety areas.
Transport Canada declined an interview request to discuss the watch list.
Larry Vance, a former safety board investigator, former pilot and now accident consultant, said the fact the flight hit the ground does not necessarily mean this was an unstable approach.
"It could have been stable until it hit. There's lots of things that could bring that airplane up short of the runway," he said in an interview, adding that it must first be determined whether the pilot was flying the plane manually, or whether it was on automatic flight.
"It's so complicated to try to put something together without the inside information."
The flight data and cockpit recorders will tell the tale, Vance said.
"I've landed on that runway many, many, many times in the past," he said. "There's nothing inherently unsafe about it."
Halifax airport spokesman Peter Spurway said planes were landing on a secondary runway at the airport on Monday.
The plane damaged some navigational aids on its way down that need repairing, but the airport can operate without them, he said.
Spurway said passengers were waiting on the runway at the airport for up to 50 minutes following the crash in a snowstorm.
"This does not happen often, and we should be grateful for that. At the same time, we do have 138 people who are walking away from an airplane crash. Yes, we can do a better job of anticipating this need, that is to remove people from a distant corner of the airfield," said Spurway, adding that first responders were on the scene within 90 seconds.
"We regret that for sure and we will, in our review, look at how we can respond more quickly."
