Tiger altitude data was wrong

An investigation into the low landing approach of one Tiger Airways' plane that contributed to the airline being grounded has found pilots used incorrect altitude information and the airline had an inconsistent safety management system.

The Australian Transport Safety Bureau (ATSB) investigated the June 7, 2011 low approach of a Tiger Airbus A320, after it approached Melbourne Airport at 2000 feet altitude rather than the 2500 feet cleared by air traffic control.

The ATSB official report, released on Monday, found that the flight crew based their descent profile on incorrect altitude data on the aircraft's display unit provided by a third party.

Flight crew were also using the flawed data for paper charts and had not identified the error when preparing for the landing approach, the ATSB report states.

It found there was an increased risk of Tiger unintentionally failing to follow published instrument approach procedures, because it was inconsistent in carrying out its safety management system for identifying and managing data base 'anomalies' or errors.

'In addition, different assumptions by the data suppliers and the operator compromised the quality assurance of the navigational data,' the report states.

CASA grounded Tiger's Australian fleet on July 2, 2011 after a series of safety concerns, including two low flight approaches into Melbourne and Avalon airports, saying it had lost confidence in the airline's ability to manage safety appropriately.

After a six-week grounding, it cleared Tiger to resume flying in August that year.

In its report released on Monday, the ATSB said that after being alerted to their low approach by air traffic control, the Tiger crew corrected their altitude to 2500 feet, continued the approach and landed.

Tiger had responded to the incident by implementing 'an auditable process for identifying and managing any navigational database anomalies in its aircraft fleet'.

The ATSB said the incident 'reinforces the safety benefits of a resilient safety management system and operator procedures' and that 'the accurate application of those procedures by all key personnel, is also important as a safety defence'.

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The truth has come to light. So it wasn't 100% pilot error but rather following an incorrect set of data during descend. But why is it that only two flights were affected? This is baffling.