Graham Warwick/ALBUQUERQUE

LOCKHEED MARTIN has begun flight demonstrations with a pre-production version of its autonomous precision-approach and landing-system (APALS). Airline demonstrations are scheduled for early February at Richmond, Virginia, following a series of approaches conducted at Albuquerque, New Mexico, with an APALS-equipped Gulfstream II.

The APALS uses the aircraft's weather-radar antenna, to produce synthetic-aperture-radar (SAR) ground scenes, which are automatically correlated with stored radar maps to provide position-updates to the aircraft's inertial navigator. The unit generates signals, mimicking a Category III instrument-landing system (ILS), to drive a flight director, auto-pilot or head-up display.

Otto Dieffenbach, business-development manager with Lockheed Martin Advanced Development Operations in San Diego, says that negotiations are under way with the US APALS launch customer, a regional-turboprop operator. This follows completion of an operational analysis which indicated a $20,000/ year/aircraft net benefit from fitting a single-channel, Cat II, flight-director-based APALS, he says.

According to Dieffenbach, work is also under way with two European operators interested in equipping identical narrow body-airliner types with dual-channel, auto-pilot-coupled systems certificated for Cat III automatic landings. An operational analysis has been completed for one operator, indicating a $40,000/year/aircraft net benefit, he says.

US Cat II certification is scheduled for mid-1997, followed by European Cat III certification by the end of 1997. Production-unit testing is scheduled to begin in late 1996 in the US launch-customer's aircraft, while testing of the production, Cat III system is scheduled to begin in early 1997 on aircraft belonging to the two European operators.

Dieffenbach says that Lockheed Martin is negotiating agreements with outside vendors to offer FM-immune ILS receivers, flight-management systems and VHF data- link modules as part of the APALS.

The GII demonstrator is equipped with a pre-production APALS, which is linked to the aircraft's flight director, allowing precision approaches to be hand flown. The system, which includes a global-positioning system, inertial- measurement unit and radar transmitter/receiver, provides a position accuracy of 1.5m.

Some 75 approaches were planned at Albuquerque to demonstrate Cat III accuracy requirements. Flights at Richmond are intended to evaluate radar correlation in winter conditions (the approach database of SAR scenes was created in the summer) as well as to allow some 75 invited pilots to fly the system.

Further demonstrations are planned at Washington DC's Andrews AFB (to the military); at the US Federal Aviation Administration Technical Center in Atlantic City, New Jersey; at Galveston, Texas (to evaluate over-water approaches); and at Houston Hobby Airport, Texas, to demonstrate the system to the US launch customer.

Source: Flight International