Air Canada's safety record

Air Canada has enjoyed one of the world's top safety records leading up to Wednesday's incident, when21 passengers were taken to hospital in Calgary after turbulence on a flight from China.

The airline confirmedthat multiple injured passengers were taken off Flight 88 after the plane was diverted during a scheduled trip from Shanghai to Toronto.

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• PHOTOS: Air CanadaAC264crashes in Halifax

During an incident earlier this year on March 29, Air CanadaFlight624touched down 335 metres short of the runway at HalifaxStanfieldInternational Airport.

Twenty-threepeople on board were taken to hospital, none with critical injuries, airport officials said.The Transportation Safety Board described the Airbus A320 crash as a"collision with terrain."

Before that incident, the 2015ranking from the Jet Airliner Crash Data Evaluation Centre (JACDEC) put Air Canada in the No. 4 spot worldwide for safety, behind Cathay Pacific, Emirates, and Taiwan's EVA Air.

AirlineRatings.com gave the airlinea seven-out-of-seven safety rating.

Air Canada is among the biggest airlines in the world in terms of the size of its fleet, with about 400 aircraft,and is the largest air carrier in Canada. In 2014, the airline and its regional carriers flew more than 38 million passengers.

Air Canada and its regional subsidiariesoperatehundreds of flights a day. The airline says its daily volume isroughly equivalent toa plane taking off once every minute, around the clock.

Overall, Airsafe.com says Air Canada has made more than 4.75 million flights over the course of its 50-year history under the Air Canada banner.

In that time, it has had three incidents resulting in fatalities since Trans-Canada Air Lines officially became Air Canada on Jan. 1, 1965, with the most recent being more thantwo decades ago.

1970, Flight 621

Air Canada Flight 621 crashed July 5, 1970, while attempting to land at Toronto Pearson International Airport.

The crash stemmed from a miscommunication between the captain and co-pilot. The spoilers were deployed earlier than the captain intended, and the DC-8 four-engine jet hit the runway hard and lost an engine.

It managed to climb again and tried to go around for a second landing attempt, but a series of explosions destroyed another engine and the wing. The plane crashed, killing all 97 passengers and nine crew members.

(The company had another serious DC-8 accident before being renamed Air Canada. On Nov. 29, 1963, Trans Canada Air Lines Flight 831 crashed while en route from Montreal to Toronto, killing all 111 passengers and sevencrew membersaboard. Investigators looked at a number of mechanical systems, but were unable to determine the cause.)

1978, Flight 189

Air Canada Flight 189 blew a tire on takeoff from Toronto Pearson International Airport on its way to Winnipeg on June 26, 1978. Bits of the tire damaged one of the DC-9's engines and the crew aborted the takeoff, but were unable to stop before the planeran out of runway.

The aircraft overshot the end of the runway and slid into a ravine.Two of the 102 passengers aboard were killed.

1983, Flight 797

Air Canada's most recent fatal incident was June 2, 1983. Flight 797 was on its way from Dallas to Toronto. While flying at 9,300 metres, smoke from a fire in the DC-9's lavatory started to fill the cabinand the aircraft's electrical systems began to fail.

The crew managed to land the plane at Cincinnati/Northern Kentucky International Airport, but were unable to evacuate everyone safely. Of the 46 people aboard, 23 died in the fire.

1989, Air Ontario Flight 1363

Although it doesn't fly under the Air Canada banner,Air Ontario, asubsidiary,had a serious crash in Dryden, Ont., on March 10, 1989. Air Ontario Flight 1363, a Fokker F28jet, crashed seconds after takeoff fromDryden Municipal Airport.

Ice and snow had not been cleared from the wings, affecting the amount of lift that could be generated. The plane struggled to gain altitudeand crashed into trees beyond the runway.

Of the 65 passengers, 21 were killed in the accident, and three of the four crew members also died.

Other incidents

Air Canada has also hadnotable safety-related incidents that did not result in fatalities.

In July 1983,Air Canada Flight 143aBoeing 767 ran out of fuel on its way to Edmonton while cruising over Red Lake, Ont. The plane glided 225 kilometres and landed at Manitoba's decommissioned Gimli airport, which was being used as a dragstrip. It led to the downed plane being referred to as the "Gimli Glider."

The Boeing 767 was the first metric plane to fly in Canada, and when the fuel computer on the plane malfunctioned the ground crew miscalculated the amount of fuel needed for the flight.

The plane landed without power and with a partially lowered nose-wheel. A handful of the 61 people aboard received minor injuries going down the rear exit slide, and there were no other serious injuries.

After the landing, the pilot and co-pilot of Air Canada flight 143 were praised for saving the lives of the 61 passengers on board. But on Oct. 4, 1983, Air Canada disciplined them for allowing the near-tragedy to happen. The pilot was demoted for six months, the co-pilot was suspended for two weeks and three ground workers were also suspended.

A 1985 Transport Canada report blamed errors and insufficient training and safety procedures.

On Dec. 16, 1997, Air Canada Flight 646 was en route from Toronto to Fredericton. The crew was relying on instruments for the landingdue to foggy weather, and just before touchdown the captain ordered the first officer, who was flying the plane, to go around for another try. When the first officer tried to pull up, the BombardierCanadairjet stalled, hit the runway and slid into some trees.

The plane came to rest with a large tree inside the passenger compartment. Of the 39 passengers and three crew aboard, nine were seriously injured.