Special Sub-Topic: Commercial Air Disasters 1988-98 Click Here To Play: Commercial Air Disasters 1988-98

On February 24 1989 an explosive decompression ripped off the cargo door of United B747 Flight 811 bound from Honolulu to Sydney. Nine passengers seated above the door were sucked out of the aircraft to their deaths. What caused the door to blow off?

All of these (Multiple malfunctions prior to accident led to damaged lock sectors, Incorrect alignment of the latch pins led to accelerated wear, Door mechanisms were not inspected each manual opening). The US NTSB's official finding was that the door was improperly latched, which was made possible by a deficiency in the design of the locking mechanisms, which allowed the door to be unlatched yet showed a properly latched and locked position.

On March 3 1991 a United B737-200 series over Colorado Springs, Colorado, was brought down by extremely adverse weather conditions, resulting in the deaths of all on board. What was the weather condition?

Low-level Wind Shear. Wake turbulence is caused only by other larger aircraft close ahead of an aircraft, such as ahead in a take-off queue. The NTSB spent three years in an exhaustive investigation, which did not conclusively explain the crash. However there were known to be 'rotors' at the time, determined by witness reports, of up to 154km/h, gusts of 90 to 136km/h and mountain turbulence from the surrounding ranges.

In March 1994 an Aeroflot A310 slammed into the ground at high speed after a series of almost undetectable rolls, yaws and pitching, followed soon after by stalls, dives, recoveries, rolls and a final spin dive. What initially caused these upsets?

Pilot's child was encouraged to 'play' with controls. The feelings of cabin crew and passengers, undoubtedly bored by the long night flight over dark, can barely be imagined as the widebody suddenly nosed up, stalled and flicked into a spin, followed by a high-speed dive of almost 40,000fpm at terminal velocity.

On June 26 1988 a new Airbus A320, operated by Air France, scraped treetops during a low-altitude flyover for passengers' enjoyment, ripping off the starboard wing and crashing in a ball of fire. What was this accident a result of?

All of these (Flyover height lower than surrounding obstacles, Slow speed, reducing to reach max angle of attack and idle engines, Late application of go-around power). Even though the A320 was a new-technology, computerised aircraft with standards of maximum safety and efficiency, this accident proved that it was an aeroplane still subject to the same laws of aerodynamics as any other - and its advanced computers were still subject to the same shortfalls as the their human operators.

Airline crashes in the '80s, '90s and today are often solved by information provided by this very important item from the aircraft.

DFDR - Digital Flight Data Recorder. Today's FDRs (DFDRs) simultaneously record 70 aircraft performance parameters, including instrument readings, flight control movements, engine performance and secondary control settings.

Discussed in an earlier question, the introduction of a new aircraft in the 1980s, caused some crew confusion and was involved in three accidents in a short space of time - all related to inexperience with the new technology. What was the aircraft type?

A320. The first fully-computerised flightdeck with fly-by-wire controls and many features and controls not known previously, such as EFIS (Electronic Flight Information System), the initial experience was similar to the teething problems of the B727 in the 1960s.

What airlines were not involved in any crashes, fatality-free or otherwise in the period 1988-98?

Air New Zealand and QANTAS. QANTAS never had any fatal crashes, only one fatality-free crash in the 1950s. Air New Zealand had one crash during a training flight in 1966 involving a small number of fatalities, and one major crash later. This was the world's fourth worst aviation accident, in November 1979, where a sightseeing DC10 crashed into Mt Erebus in Antarctica during whiteout conditions. United has had its fair share of crashes during this period but it is a major airline with extensive operations.

What was the cause of Air Ontario's F28-1000 Fokker Fellowship crash during takeoff on March 10 1989, at Dryden Airport, Ontario, Canada, with most on board surviving?

Aircraft icing. Due to a series of delays and false starts, by the time the aircraft was given the final go-ahead to taxi, it had been a considerable length of time since being de-iced; the crew being stressed and frustrated were prepared to forgo another de-icing, which would have saved the aircraft and their lives.

What has prevented stalls and almost definitely crashes, of commercial jetliners in the 1980s and '90s?

All of these (Aircraft stick-shaker mechanism, Automatic nose-down approaching stall, Fly-by-wire anti-stall computer system). They are all standard on today's modern jet airliners, but small general aviation types only have the simple stall buzzer (although proper training, experience and attention is sufficient).

The crash of a Thai International Airways A310 in July 1992 over Nepal, was an accident that should never have happened. It was caused by...

Crew misunderstandings. A complex series of seemingly inconsequential frustrations, misperceptions and misunderstandings, finally worked to deprive the captain of "the plot" - with devastating consequences. The language of aviation is universally English - ie. for all radio communications.