Evaluation of ICAO Recommended Category II Approach Light Systems for High Performance Aircraft

An evaluation of approach lighting for Category II operations was conducted at the Federal Aviation Agency's National Aviation Facilities Experimental Center, Atlantic City, New Jersey.

The evaluation program was coordinated within the International Civil Aviation Organization (ICAO) to reach agreement on approach light standardization within the inner 1000 feet of the system for Category II operations. Tests were carried out in simulated and actual Category II weather conditions. Twenty-five subjects flying a DC-6B aircraft and seven subjects flying a Convair 880 aircraft participated in the weather simulation phase. Two subjects flying a DC-7 aircraft and seven
subjects flying Gulfstream aircraft participated in the actual weather phase.

Test results indicated that the following modifications to the inner 1000 feet of the United States Standard ALS would substantially improve approach success for high-performance aircraft in Category II operations.

1. Add red side rows of barrettes in line with the runway
   touchdown-zone barrettes.
2. Add a white cross-bar 500 feet from threshold between the
   rows of red barrettes.
3. Fill in the gap at threshold by continuing white-centerline
   and red-side-row barrettes to within 100 feet of the
   threshold.
4. Delete the red-wing bars 100 feet from the threshold.
5. Delete the condenser-discharge lights.

It was recommended that a service test be conducted on the system at a major international airport having a high percentage of low visibility conditions.