Helicopters are operated under ‘Visual Flight Rules’ (VFR) and, as such, are required to be able to visually determine position by reference to the ground or water at regular intervals.
Helicopters used by the AAD in Antarctica use ‘dead reckoning’ as the primary form of navigation. Dead reckoning is the use of maps and known landmarks combined with aircraft airspeed to determine position.
The introduction of GPS over the last fifteen years or so, combined with increasing satellite reliability, has allowed aircraft position and ground speed to be displayed instantly to the pilot. Although this is an enormously useful capability, the pilot must still be able to navigate by dead reckoning in case of system failure.
GPS is particularly useful when flying over featureless terrain like sea ice or the ice plateau, with few or no mapped landmarks. GPS also allows aircraft position to be passed to communications staff instantly.
We plan to install a satellite tracking system in the helicopters in the 2007–08 season. The system has the capability to automatically transmit position every few minutes to a ground-based computer. Overlay of this information on to a map will allow ground based communications staff to monitor the aircraft flight path independently of normal radio methods.
Many of the programmes currently supported by helicopters are reliant on satellite-based technology. Although GPS navigation is not a requirement for helicopter navigation, it is required to be fitted to meet the requirements of these programmes. Such programmes include deploying buoys onto ice floes, depoting equipment in featureless terrain and deploying stakes to monitor glacier movement.
The position of these items can now be accurately recorded making recovery much easier.