Travel by aircraft is normally an extremely safe method of transport. Statistics show that each year some 1100 people are killed in air accidents throughout the world – compared to 40,000 people killed in road accidents in the USA alone.
Yet accidents have occurred since the earliest days of flight. The first to be recorded was in 1908. Lieut Thomas C. Selfridge of the US Army, a distant cousin of the founder of the famous London store, was killed when Orville Wright’s aircraft crashed at Fort Myer, Virginia, after a wooden propeller splintered. Wright, one of the pioneers of manned flight, escaped with a broken leg. Selfridge, his passenger, died almost instantly.
When a modern aircraft crashes there is always an intensive investigation to establish the cause so that lessons can be learned to prevent future tragedies. This applies whether it is a light aircraft with only a couple of passengers or a jumbo jet airliner carrying more than 500 people.
Whether the suspected cause is a terrorist bomb or a faulty component, the principles of the inquiry are the same.
The first steps include recovering the wreckage, which may be on a mountain or under the ocean. Air accident investigators, who are usually employed by the transport department or air travel authority of the country concerned, go to the scene of the crash. They map out the area across which wreckage is scattered, since this may reveal the sequence in which the plane broke up. Samples of all parts of the wreckage are taken in case they might indicate some reason for the crash. Metals crack or melt differently according to types of heat, pressure or blast.
Recovery and examination of the bodies will be conducted by medical experts, who can determine the time and cause of death which may contribute to establishing the cause of the crash.
The worst single year for aircraft accidents was 1985 when more than 800 people died in two crashes involving Boeing 747 jumbo jets. At first, it was thought that the two crashes were caused by a mechanical fault in 747s. The investigators, however, succeeded in disproving the theory.
The first crash was an Air India 747 bound for Delhi from Vancouver via London. At about 31,000ft above the North Atlantic, west of Shannon in Ireland, the aircraft disintegrated and plunged into the ocean with the loss of all 329 people.
Although more than 130 bodies and some pieces of wreckage were recovered quickly, it took three months to locate and map out of the rest of the aircraft. Most of it was on the seabed, 6500ft (2000m) below. It was located using sonar equipment and mini-submarines working from surface recovery vessels.
The first and most important pieces of wreckage to be recovered were the flight data recorder and cockpit voice recorder. The recorders are often called ‘black boxes’. In fact, they are usually bright orange or red, so they can easily be spotted.
Terrorist bomb
When the cockpit voice recorder, which captures on tape the sounds inside the aircraft’s cockpit, was replayed, investigators believed they heard the sound of an explosion. It was recorded on the last millisecond of tape before the aircraft disintegrated. Although there was no direct evidence of a terrorist bomb, there were enough signs from the wreckage to make it a strong possibility. The seats were scorched underneath and the front cargo door appeared to have been blown out, while others remained intact.
Scientists also pinpointed where the recovered bodies had been sitting in the airliner and established patterns of different injuries, which supported the theory that the aircraft exploded in midair.
Another clue came when Canadian investigators discovered that the aircraft had been loaded with the bag of an Indian passenger who had not boarded the plane.
A similar set of circumstances surrounded an explosion of a bag at Narita Airport in Tokyo, which killed two baggage handlers, at about the same time as the Air India crash. Both bags were later traced back to one man in Vancouver and the explosions were believed to be the work of Sikh terrorists.
Two months after the Air India crash, a Japan Airlines 747, on a flight between Tokyo and Osaka, crashed into Mount Osutaka, 70 miles (113km) north of Tokyo. All but four of the 528 passengers died, making it then the worst disaster involving a single aircraft.
A few minutes after takeoff, a loud bang was heard from the rear of the cabin, followed by the complete failure of all instruments. The crew fought for 32 minutes to keep the plane airborne until it crashed in a spot so remote it took 14 hours before the first rescuers and investigators arrived. The aircraft had almost completely disintegrated, with wreckage covering a wide area. The four survivors had been sitting together in seats in the centre.
Although there was a tape of the conversations between the crew and the air-traffic control, it revealed little of value. However, the history of the plane showed it had been repaired by its makers, Boeing after landing badly at Osaka in 1978, scraping the rear on the tarmac.
Examination of the wreckage showed that the repairing engineers had left a very small gap between reinforcement plates on a riveted join in a bulkhead. This gap had exposed the join in a bulkhead. This gap had exposed the join to pressure and it had eventually ruptured, allowing air from the cabin into the tail section. This had snapped hydraulic control lines, ripping off the rudder and the vertical stabilizer fin, which made the aircraft impossible to control, despite the crew’s desperate half-hour struggle.
Picture Credit : Google
