A spokesman for the Russian airline Kogalymavia, or Metrojet, whose jet crashed in Egypt, said Monday that the cause was “external influences.” But within hours, an investigator told Reuters that there is no evidence of an external impact on the Airbus 321 and that the pilot did not make a distress call.
“The plane was in excellent condition,” Alexander Smirnov said. “We rule out a technical fault and any mistake by the crew.”
The airline is insisting that its own maintenance and safety procedures cannot have been at fault, but they are not denying that the airplane broke up in the air at 31,000 feet. Instead, the airline is saying that they don’t believe that a mechanical or technical fault in the Airbus, for which they would be responsible, was the cause.
ADVERTISEMENT
While nobody can yet be sure of the cause, new images from the crash site confirm that the main part of the wreckage and the tail section were three miles apart. The aerial footage taken by RT shows the wings to have been intact on impact.
This reinforces the belief that the tail was severed from the rest of the airplane at the point when it broke up and fell separately. It all happened in 25 seconds: the A320’s fate was very sudden, as revealed in data released by FlightRadar24.
This trace of the flight’s last moments shows the altitude and speed of the jet immediately following its mid-air breakup. The nose pitches up sharply as it would if the tail broke off – the wings are generating lift without the counterbalance of the horizontal stabilizer, the airplane stalls and drops and, gaining speed again the nose rears upward one last time before losing all lift. In ten seconds the airspeed remains constant in the dive but the ground speed – the speed of the airplane's actual passage over the earth – drops precipitately from 175 knots to just 47. Without the tail the crew would have had no control over this terrifying sequence.
The main wreckage shows evidence of being consumed by fire caused by fuel in the main tanks igniting—whether in the air or on impact cannot yet be determined. But—significantly—the tail section shows no sign of fire or smoke damage.
This could be the most important clue to the initial break-up. If a bomb or other kind of explosive device ripped open the fuselage at the tail, then it would have left signature evidence of flame and scorching on the wreckage.
It is here that the use of the word “explosion” becomes potentially confusing if employed as an all-embracing description.
The alternative to an explosive device is an explosive decompression in which a sudden structural failure allows pressurized air in the cabin to escape in a ferocious blast—it’s a “clean” explosion involving no ignition or combustion but is just as lethal.
In 1985 the worst single aircraft accident in history was caused by an explosive decompression of the rear pressure bulkhead of a Boeing 747 operated by Japan Airlines. However, in this case the airplane did not break up in the air. The blast released from the failed bulkhead burst into the vertical stabilizer and crippled the rudder. Although the 747 continued to fly for another 32 minutes the pilots could no longer control it, and it crashed into a mountainside, killing 520 people.
What was unusual about this was that the 747 had not been used for its normal role on long-haul international flights but for frequent flights between Japanese cities with dense seating. This put heavy stress on the pressure bulkhead, the kind of stress that causes metal fatigue. Although a fatigue crack had been found earlier in the bulkhead, investigators in their final report on the crash discovered that it was not properly repaired.
The Russian A321 had not been used on routes with that kind of frequency and for an airplane of its age, 18 years, had logged a relatively low number of flights, 21,000. Normally that record would not imply metal fatigue problems. But, as I have reported, the anomaly in this airplane’s record is the heavy tail strike landing it suffered at Cairo in 2001, causing serious damage to the rear fuselage.
As the airline reasserted when saying that the cause of the accident was “external,” the A321 was repaired and inspected (and would have had regular subsequent checks) and the spokesman denied that there could have been any connection between the earlier tail strike damage and the crash.
A definitive verdict should come when data from the airplane’s black box is analyzed. But in a case like this, with so much physical evidence already apparent at the crash site, experienced crash investigators will have “read” the wreck and drawn some preliminary conclusions from it.
