Planes seating more than 14 people suffered 10 events that killed passengers last year, the same number as in 2013, when 220 travelers died, and 2012, when 416 perished, Ascend said.

Cruising Height

The three major crashes were unusual because each involved a modern, western-built model, with the Boeing 777 wide-bodies that operated Malaysian Air flights MH370 and MH17 dating from 2002 and 1997, respectively, and AirAsia’s lost Airbus Group NV A320 narrow-body built only in 2008.

All three jets had also been flying at cruising altitude, with MH370 having leveled out at 35,000 feet after departing Kuala Lumpur for Beijing before doubling back over the Malay peninsula for unexplained reasons. MH17 was operating at 33,000 feet when it plummeted to the ground, and QZ8501 was at 32,000 feet when its pilots asked to go higher in stormy weather.

The Netherlands-based Aviation Safety Network, which recorded 21 fatal airliner accidents last year, including cargo flights, said 13 crashes occurred in the en-route phase, versus three during both the initial climb and landing approach. One deadly event happened during landing itself and none on takeoff.

Suicide Theory

By contrast, between 1959 and 2013, 47% of crashes and 40% of deaths came during landing, Malaysia-based Maybank said this week after the AirAsia loss, citing Boeing’s Statistical Summary of Jet Airplane Accidents. The cruise phase accounted for only 10% of crashes, though survivability was lower, so that it produced 20% of fatalities.

While full explanations have yet to be formulated for the three worst incidents of 2014, safety experts have suggested the disappearance of MH370 -- and its 227 passengers -- most likely involved pilot malpractice, since all devices indicating the plane’s position were turned off. A search for debris and the 777’s black-box flight recorders that might reveal the truth of its demise continues off Australia.

Malaysian Air flight MH17 was downed in a war zone in eastern Ukraine, killing all 283 passengers, after being hit by “a large number of high-energy objects,” the Dutch Safety Board said Sept. 9. The board stopped short of laying the blame on a ground-to-air missile strike, which the U.S. has said was most likely the cause and probably fired by pro-Russia rebels.

Stray Fire

The Dutch -- leading the investigation because more than 190 victims were from the Netherlands -- cautioned that the probe is in its early stages, pledging only that a definitive study will come within one year of the July 17 tragedy.

Another incident classified with MH17 as non-accidental by Ascend saw a woman die on a Pakistan International Airlines flight after an Airbus A310 carrying 196 passengers came under fire, possibly by AK-47 assault rifles, while landing in Peshawar. The incident came two weeks after a Taliban attack on Karachi airport killed 36 people, though none were on aircraft.

Excluding “acts of violence,” the 2014 death-toll would have been 600, the highest since 2010’s 822, Ascend said.

In the AirAsia crash, which killed 155 passengers and involved an experienced pilot who failed to transmit a distress signal, it’s possible weather played a key role. The jet appears to have flown into a storm cloud where its engines could have been affected by ice formation, researchers from the Indonesian meteorological office said in a report citing data from the jet’s last known location.

Tropical Storm

Among other events in 2014, the worst involved the loss of a McDonnell Douglas MD-83 jet flying for Air Algerie in Mali on July 24, killing 110 travelers, and a TransAsia Airways Corp. ATR-72 crash in Taiwan a day earlier, with 44 passenger deaths.

Weather was a factor in both cases, with the MD-83 crew encountering a storm about 40 minutes after takeoff and the ATR turboprop destroyed on a second runway approach amid heavy rain from tropical storm Matmo. Some 15 travelers also died when a Nepal Airlines de Havilland Canada DHC-6 Twin Otter turboprop hit jungle on a 7,000-foot hillside in poor weather on Feb. 16.

A crash that killed 42 people in Iran in August came after the country sought to develop its own aerospace industry to escape the impact of western sanctions. The government later grounded the Iran-140 turboprop to determine whether a spate of accidents could be traced to faults intrinsic to the plane.

The two other fatal events concerned a Twin Otter that hit a mountain in Papua New Guinea in poor visibility in September and a Russian-built Antonov An-26 that crashed in Tunisia after flying from Libya in February. Both models are turboprops.

About 100,000 flights a day land without incident worldwide, the International Air Transport Association says. In 2013, passenger trips on airlines exceeded 3 billion.

--With assistance from Andrea Rothman in Toulouse and Kyunghee Park in Singapore.

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