Two passenger jets came within less than two minutes of a head-on collision off the south-west coast after a series of errors by a cockpit crew and air traffic controllers.
On the morning of November 10th last year, the Air France and Airtours International planes were just 20 miles apart when one took evasive action, according to a report by the Department of Transport's air accident investigation unit (AAIU). By the time the Airtours plane descended to a safe level, the aircraft were less than a minute apart.
Air traffic controllers (ATCs) at Shannon, said the report, failed to notice a light which flashed on screen for at least 40 minutes, warning them of the impending catastrophe. Errors were also made by controllers in Scotland, who also had responsibility for the flight concerned.
Even when it was noticed that the planes were about to crash, the message sent by controllers to avert the accident was "wholly inadequate", the report found. Controllers, it said, had failed to adhere to published procedures in the run-up to the near miss.
The Air France Boeing 747 was on a flight from Havana to Paris, and the Airtours Airbus A330 was heading to Cancun, Mexico from London. The two would have collided at 10.59 a.m., but at 10..57 the Airtours plane began descending after the crew were alerted to the situation. Thirteen seconds after starting his descent, the pilot could see the Air France plane approaching.
The initial error was made by the commander of the Airtours plane, who gave an incorrect flight time estimate to ATCs based at Prestwick in Scotland. When the plane entered the Shannon Oceanic Transition Area (SOTA) and came under Shannon radar control, ATCs there did not pick up on the fact that the plane was flying one hour ahead of the time supplied. It was normal practice, the report said, for ATCs to check and confirm the time of flight clearance requests made by cockpit crews, and to advise of corrections if necessary.
On this occasion, however, the "human factor failure" of the cockpit crew of the Airtours plane, three ATCs at Prestwick and four controllers at Shannon "combined to produce an unthinkable situation whereby two passenger aircraft were allowed come within minutes of a possible head-on collision".
The crash was avoided because of a "fortuitous and timely" position report by the crew of the Airtours plane, eight minutes before the planes were due to cross. Controllers at Prestwick immediately began to look for a safe level to which the plane could descend, but the errors did not end there, according to the report.
A message was transmitted to the communications centre at Ballygirreen, Co Clare, to be relayed to the pilot of the Airtours plane, including the words "priority due traffic descend now". The use of the word "priority", said the report, was "wholly inadequate", as this was frequently used in air traffic control messages to Ballygirreen.
"With the belated realisation of the developing situation by Shanwick (Prestwick ATC), the urgency of the situation should have been addressed by a more compelling word or words on the messages such as 'avoiding action' or 'immediately' or 'immediate avoiding action' ".The controllers at both airports were relieved of their duties for debriefing, counselling and retraining, where necessary, the report said.
