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Halifax plane crash raises questions about Canada’s airport landing systems

Halifax plane crash raises questions about Canada’s airport landing systems

There’s been predictable speculation about why an Air Canada jet touched down short of the runway during a snow storm at Halifax’s Stanfield International Airport early last Sunday morning, much of it focusing on the pilots’ actions.

The Transportation Safety Board (TSB) wrapped up its investigation of the crash site Tuesday and now begins its analysis of the Airbus A320’s voice and flight-data recorders, as well as other evidence including weather conditions, condition of the plane’s flight systems and airport services.

Barring an interim report or recommendations, it could be a year before the TSB issues its final verdict on what caused Air Canada flight 624, with

133 passengers and five crew aboard, to radically miss its approach to Runway 5.

The jet collided with the runway’s instrument-landing system (ILS) array and touched down more than a thousand feet short of the runway threshold before briefly rising back into the air. It bounced onto the runway, losing its landing gear and an engine before skidding to a halt in the snow beside the runway. Everyone escaped but more than two dozen, including the two pilots, suffered mostly minor injuries.

The plane apparently is a write-off after what was initially termed a ‘hard landing.’ The wreckage has been removed but airport spokeswoman told Yahoo Canada News on Wednesday the runway may not open for a couple of days while it’s assessed to see if repairs are needed.

While the initial focus has been on the possibility of pilot error, anyone who’s watched the program Mayday knows it’s often a series of problems that can open the door to an air disaster.

Factors could include the procedures for landing an aircraft in marginal weather conditions and the equipment available to help the pilot make that landing safely.

Modern passenger jets are equipped with an array of systems to help pilots with their approach to the runway, including radar, satellite-based global positioning systems (GPS) and other electronics to ensure they line up properly with the tarmac.

Major airports also offer a suite of systems to guide the aircraft in to touchdown, communicating with the plane’s systems, such as ILS and GPS, to maintain the proper glide slope – the correct vertical and horizontal position with respect to the runway. But the most precise systems are not necessarily available for every runway.

Stanfield has two main runways; 5/23 and 14/32 at right angles to each other. Runways carry two numbers that indicate which direction is being used for takeoff or landing. The navigational aids to landing differ at each end of the runway.

The Air Canada flight used Runway 5, the longer of the airport’s two runways, apparently because of prevailing wind conditions.

Halifax runway had different landing systems available

According to Nav Canada, the private agency that operates air traffic control at Canadian airports, that runway has four instrument approaches available. Two utilize GPS-based guidance to provide vertical (height) and lateral (left or right of the runway) position information, while two offer only lateral guidance.

Nav Canada spokesman Ron Singer would not comment on what approach procedure was being used, saying that was up to the TSB to reveal.

Backstopping these landing systems is an array of lights used for decades to help keep the pilot lined up.

“If you’re too high they’re white or whatever and if you’re too low they’re red and if you’re right in the middle they’re green,” said John McKenna, chief executive officer of the Air Transport Association of Canada. “But how much can you see those in the weather?”

The pilot in command reportedly circled the airport for as long as 45 minutes waiting for a break in the storm before attempting the landing.

An American aviation safety expert with knowledge of the Canadian flying environment, including Halifax, said he understood the flight was making a non-precision approach, which does not use the full suite of landing aids the Airbus was capable of utilizing.

“With a non-precision approach they’re flying a heading to the runway that’s lined up with the runway centre line,” the expert, who did not want to be named but who has worked on crash investigations in the U.S. and Canada, told Yahoo Canada News.

“You get no vertical guidance whatsoever. It’s just lateral guidance. Because of the lack of vertical guidance you have to be more on the ball about where the aircraft is so you clear all the obstructions.

“They were using Runway 5 because the precision approach on 23 was not available because of the tailwind component.”

Neither Nav Canada nor the TSB would comment on whether the pilots were using a precision or non-precision approach.

McKenna said Runway 5/23 is considered a secondary strip not used as much as Runway 14/32. Television simulations seem to indicate the aircraft was approaching from the west, suggesting a change in the normally prevailing westerly winds.

“So it shows there were either wind shifts or the storm was really coming in from the northeast,” he said. “So that’s why they’re using that strip rather than the usual one.”

The U.S. expert, who is also a pilot, said pilot unions have been pushing U.S. and Canadian aviation authorities to set up precision-landing equipment (known as LPV) at both ends of airport runways.

“We want precision approach capability in every runway end. Canada and the United States both are in the process of doing that,” he said. “We’re just maybe not doing it quick enough because most of the technology’s already installed in the aircraft.”

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Northern airports need precision-landing capability, says expert

The problem is especially acute in the north, he said, because a lot of international flights use northern Canadian airports as en route alternates in case of emergency.

It’s also an issue with smaller southern airports that don’t have the flight volume to push the investment up Nav Canada’s priority list, he claimed.

“For the Canadian operators, you’ve got to be a better pilot to stay up to speed in flying a non-precision approach,” the expert said.

However, Singer said via email that the there are more than 200 LPV approaches across Canada at airports ranging from Toronto to Taloyoak, Nunavut, and including at all four runways at Halifax.

Air Canada has said weather was not a factor in the crash, that conditions were safe for landing, something ATAC’s McKenna disputes.

“I think it was entirely weather-related,” he said.

The U.S. expert said Halifax has a reputation for rapidly shifting weather conditions that makes flying into Stanfield challenging.

“It could be sunny and clear and two minutes later it’s raining sideways with low visibility and high wind,” he said.

It’s conceivable that the hole in the snowstorm the pilots perceived when they decided to begin their approach could have disappeared as they neared the runway, he suggested.

It’s also not clear whether crosswind gusts were a factor in the A320’s premature descent.

“When you’re flying into the wind and it’s steady you can deal with it,” the expert explained. “But if it’s gusty and it sheers out, well you can get a downdraft pretty doggone quick and that could lead to somebody touching down short in a high wind situation.”

Final decision whether to land is always up to pilot

The pilot in command would have been in communication with the control tower, which an airport spokesperson said was staffed that night. But the final decision whether to land at Halifax or divert to another airport would be up to the pilot.

Whether he made a mistake in judgment will be up to the TSB to determine.

What McKenna and the U.S. expert agreed on, though, is that the pilot likely felt under no corporate pressure to land the flight in Halifax to avoid disrupting passengers’ travel plans or Air Canada’s schedule.

“The pilot has the last word in safety,” noting the airline industry balked at an NDP-proposed passenger bill of rights that would have included high penalties for late arrivals or disrupted travel.

“You’re putting the go or no-go decision in the the accountant’s hand rather than the pilot’s hand because if he doesn’t land the plane or take off, the company’s going to have so many fines to pay.”

If there was any pressure, the U.S. expert said, it was what the pilots may have put on themselves to deliver their passengers to Halifax as planned, pointing to the time they spent circling the airport. But not at the cost of safety.

“But knowing the folks there that we know, they would not have shot that approach if they did not have the runway in sight,” he said.”If they didn’t have the runway in sight I’m sure they would have diverted and wouldn’t have hesitated.”