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Approach design a key factor in Lockhart crash says lawyer/pilot

FOR IMMEDIATE RELEASE - 12 May 2005
CONTACT - Peter Carter on 3210 3409 or 0422 445 599

The design and choice of the landing approach being used when the Trans-Air Metro slammed into Iron Range on descent to land is a key factor in the tragedy according to an Aviation law expert.

Peter Carter* of Brisbane law firm Carter Capner says the runway 12 GPS approach which was apparently being used by the aircraft had inherent risks.

"GPS approaches require descent and approach along an imaginary extended runway centreline. In this case the extended centreline of runway 12 at Lockhart River requires an inbound descent for about 25 kms over very hilly terrain."

From the known information, it appears that the aircraft struck a hill in the Iron Range peaks (a hazard marked on the runway 12 GPS approach chart at 1625 feet) about 3 km north of the published approach path.

"Given that en-route GPS track deviation can be up to 9 km, the descending aircraft could have been near a hazard at a point when the pilot was not alert to that hazard."

Another explanation is that the pilot was mistakenly heading for "waypoint foxtrot" about half way along the published approach when the impact occurred.

This does not explain why the aircraft was flying lower than the specified minimum height of 2200 feet at that stage of the descent - an issue that is related to either equipment defect or aircraft operation.

"Lockhart River is a coastal airstrip in low lying terrain. The aerodrome is equipped with a navigation aid that would have allowed a non-GPS approach from the south east - over the sea - which would be the preference for many operators."

The airstrip was designed and constructed long before the application of GPS for aircraft landings. It has two approved GPS approaches, the other one being from the opposite direction (south east over water). "The ATSB enquiry should consider the unsuitability of dual GPS approaches at some aerodromes."

"There's no denying that the features of the approach path combined with the idiosyncrasies of GPS are likely to be a significant feature of this investigation."

GPS approaches are published by a government body, Air Services Australia and are designed according to international standards. Air Services has done considerable research into the reliability of GPS navigation in Australia. Its Ground Based Regional Augmentation System (GRAS) project adds further safeguards to possible GPS location errors:

http://www.airservices.gov.au/pilotcentre/projects/gnss/gnss_gras_ion2002_paper.pdf

En-route GPS navigation for Instrument Flight Rules has been allowed since 1994. It has been available for approaches progressively since 2000. One advantage of GPS approach is that the pilot can descend to a lower 'minima' (as compared to other types of instrument approaches) before having to make the decision to land or abort.

The GPS approaches for Lockhart River are quite recent.

The percentage of general aviation pilots who have undergone the extensive training needed to fly GPS approaches is small and the number of light aircraft equipped with the high standard of on-board GPS receivers needed is small.

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