The older variant, the 737-200, was involved in yesterday's crash. On average, since jets first started flying, out of 1 million flights there have been 1.9 crashes involving total destruction of the aircraft. For Boeing 737-200s the record is 1.1 per million flights, about twice the average for Boeing 737s generally, whose updated variants are still in production.
Built for short-haul flights and able to carry between 100 and 150 passengers depending on the configuration, the Boeing 737 is the world's best-selling commercial airliner with 2,658 sold since 1967.
The aircraft involved in yesterday's crash had been sold to Air Algerie as a passenger aircraft and had been converted for freight operation. Freight aircraft have a notoriously poor safety record, partly because they are often nearing the end of their useful life. Most notably, the Amsterdam air disaster in October 1992, which killed at least 39 people on the ground and the four people on board, was caused by a Boeing 747 freighter which lost two engines after the pins holding them on failed.
A series of similar disasters involving 747 freight aircraft led to the world's biggest aircraft modification programme as the pins had to be changed.
The most recent crash involving a 737, when 132 people were killed near Pittsburgh, in the US, in September, has still not been explained. Possible rudder problems were the most likely cause and are thought to be responsible for the crash of another 737 at Colorado Springs in 1991. The Seattle Times, Boeing's home-town newspaper, reported in October that the 737's rudder had prompted 46 "service difficulty reports" to the US aviation authorities. In 1988, the US Federal Aviation Administration ordered thousands of rivets to be replaced on ageing 737s to stop their fuselages cracking. The ruling followed a metal-fatigue accident when the top half of an aircraft tore off in Hawaii, sucking a stewardess out of the plane to her death. This was similar to an accident in 1981 when a 737 disintegrated in mid-air over Taiwan, killing all 110 passengers and crew.
There have been two disasters in Britain involving 737s in the past decade, neither of which bear any similarity with yesterday's crash. In August 1985, 55 people died at Manchester Airport when a British Airtours 737 burst into flames as it was about totake off for Corfu after an engine disintegrated, setting fire to the fuselage. Most were killed by poisonous smoke before they could get out.
In January 1989, 47 people died and 67 were seriously injured when a British Midland 737 crash-landed on the M1 motorway at Kegworth while trying to make an emergency landing at East Midlands airport following an engine fire. The pilots had mistakenly closed down the wrong engine and the plane crashed just short of the airport where it was trying to make an emergency landing.
Two new variants of the Boeing 737 have recently been announced, the 700 and 800, and three other variants - the 300, 400, 500 - are still in production.