Airspace Management

The amendments were proposed by Australia, Fiji, Tahiti, New Zealand, Papua New Guinea and the US and are likely to be introduced initially on the major trunk routes connecting Australia and New Zealand with the west coast of the United States.

Because this will be the first time that a distance based (rather than time based) longitudinal separation has been applied in a procedural environment, these states must now go through an intensive process of operational trials supporting development and validation of procedures before the reduced separation can be implemented. With work on these already underway, the first routes could be implemented in six months to a year.

Each state will be required to develop procedures, but in practice, ICAO expects this will be a regional effort between all states participating along a particular route, and that the reduced separations will apply along the entire length of the route. Interfacing between airspace which can apply the 50/50 separation and that which has not implemented the new standards would be extremely complex, so it will almost certainly apply exclusively to a whole route or not at all.

In the development of procedures, ICAO has specifically earmarked procedures for deviation around weather and contingency procedures in the event of radio failure for particular attention. Only when these procedures have been developed to the satisfaction of ICAO will states be able to implement the separation reductions.

A further condition relates to the development of appropriate systems and infrastructure for monitoring navigation accuracy of aircraft operating on the route.

Aircraft operating the 50/50 separation minima must be RNAV equipped and certificated to a navigation performance minimum of RNP10. At present, almost all the aircraft operating on the main US/Australia/New Zealand trunk routes are FANS-1 equipped Boeing 747-400s which are RNAV equipped, certified to RNP10, and have a controller pilot datalink communications (CPDLC) capability.

Although there is no specific communication requirement for implementation of the 50nm (93km) lateral separation, where procedural control is sufficient, there is a specific requirement for direct controller/pilot communications—either HF voice or CPDLC—for the 50nm (93km) longitudinal separation. With its CPDLC capability, the FANS-1 package gives pilots access to both communications options.

Documentation amendments have been proposed to the global PANS-RAC (Procedures for Air Navigation Services – Rules of the Air and Air Traffic Services) to allow the 50/50 separation minima to be applied worldwide as and when states are able to meet the procedures and monitoring requirements, and there is a critical mass of RNP10/RNAV certified aircraft able to operate the routes.

The proposed PANS-RAC amendments will be submitted to the Air Navigation Commission in October this year, and will probably be implemented by November 1997.

Combined GPS/GLONASS Receiver

Details of a combined GPS/GLONASS navigation receiver, developed jointly by the Navigation and Flight Guidance Systems (NFS) subsidiary of Daimler-Benz Aerospace and the St Petersburg based Russian Institute of Radio Navigation and Time (RIRT) have just been released and production models should be available by the end of this year.

Prototypes of the ASN-22 (Apparatus for Satellite Navigation) are currently undergoing final testing and pre-production models will be available to launch customers ahead of the official December launch date. The receiver is capable of simultaneously processing the signals of both the Russian GLONASS satellite system and its US GPS counterpart.

By simultaneously receiving signals from both satellite systems, the ASN-22 gives access to a total of 48 satellites (24 GPS and 24 GLONASS satellites), allowing much greater redundancy of coverage. NFS says that, if GPS only is considered, the minimum number of satellites in view in the worst case locations in Europe is four (assuming an elevation mask angle of 10 degrees). If both GPS and GLONASS are taken into account, this figure changes to nine.

“The use of both GPS and GLONASS together allows, even under the worst case situations sufficient redundancy for the detection or even isolation of malfunctioning satellites and for performing integrity monitoring calculations, such as RAIM (receiver autonomous integrity monitoring),” says NFS.

“For the first time, a combined GPS/GLONASS receiver was integrated into the size of a standard European printed circuit board. The ASN-22 is an 18 channel receiver which processes the signals of both satellite systems at a higher level of accuracy, availability, and integrity than a GPS only receiver.”

NFS says it is suitable for stand alone applications as well as for integration into complex navigation systems.

“It is capable of processing the differential corrections received from a ground station and thus improves the accuracy of the navigation solution to less than five metres,” says NFS.

Prices for the ASN-22 start at $US5690 for a single unit without documentation and software, falling to$US5090 per unit for orders of 26 to 50 units. Prices for an ASN-22 kit including documentation and software for R&D/special purposes, start at $US5990 for a single unit.

An evaluation kit, which includes a single ASN-22 module, documentation, software, a graphical user interface for date evaluation, external power supply, and combined GPS/GLONASS antenna (including cable), costs $US8990.