AN Aer Lingus jet from Dublin with 319 passengers on board descended too fast and had to abort its landing, an air accident report just published has revealed.

The scare, in fine weather and good visibility, came after the first officer miscalculated the Airbus's height on approach to Chicago's O'Hare airport.

The plane was 774ft too low because the altitude of the airport had not been taken into consideration, but the pilot was able to increase power and circle again before making a safe landing.

There was no injury or damage, but Aer Lingus was criticised for "inappropriately" reporting the incident on September 16, 2006.

It was four months before the Air Accident Investigation Unit (AAIU) was informed, said the report. By then, much of the information about the incident had been discarded.

It said Aer Lingus "provided no guidance" to its air safety office (ASO) about the statu- tory obligation to report operational events from a confidential report sent to them by a pilot.

None of the staff members in the ASO had flying experience and the head of air safety felt he was "somewhat limited" in his ability to assess the incident "as his background was technical without any flying experience," the report said. The lack of experience in the air safety office "impeded its response to this operational occurrence" it said.

"The delays, both individual and systemic, in reporting and detection of the incident, were excessive," the report concluded.

power

The AAIU said it was notified of the Chicago incident on January 9, 2007 -- nearly four months after the incident.

By that time, most records concerning the flight had been discarded, other than the airline's flight data monitoring (FDM) data.

"Although the aircraft was not in any immediate danger during the occurrence, the AAIU had concerns due to the reported late Air Traffic Control (ATC) clearance for a non-precision approach, the incident itself and the amount of time this incident was within the operator's [Aer Lingus] system without action or the AAIU being notified," it said.

The plane was flying from Dublin to O'Hare when the incident occurred.

The 48-year-old commander, who was flying the Airbus A330-301, briefed the 42-year-old First Officer, for an instrument landing approach to each of Chicago's three runways which were in use.

The report said: "On realising they were too low, power was increased and subsequently go-around power was selected for a short period. The aircraft climbed to the proper profile and a normal landing ensued."

"The maximum altitude deviation below the correct flight path was 774ft." The pilot later told investigators he had not taken the altitude of the airport into account when mentally calculating the rate of descent needed for landing.

"He believed this was due to insufficient time to brief for the approach and an impression he was too high."

Uncertainty

The pilot later submitted a confidential report to the airline's air safety office three or four weeks after the event.

The AAIU report found that the Aer Lingus flight data monitoring system, both handling and support agreements, "impeded the speedy analysis and reporting of occurrences".

It found the pilot inappropriately reported the event through the ASO confidential reporting system. And the First Officer had not properly monitored the approach, a contributory factor, as was the ATC phraseology used which was unfamiliar to aircrew and "may have introduced uncertainty".

The 58-page report into the incident made six safety recommendations, including that Aer Lingus review its air safety manual to ensure compliance with mandatory occurrence reporting procedures.

- Michael Lavery