Reduced Approach Lighting Systems (ALS) Configuration Simulation Testing

The availability of Global Positioning System (GPS) approaches has already increased the number of runways capable of handling Instrument Flight Rule (IFR) approach operations. A major factor in upgrading the instrument capability of these runways is, and will remain, the need for installation of many new approach lighting systems (ALS). Therefore, it has become necessary to re-evaluate the present standard systems to identify possible means by which installation, operation, and maintenance costs can be reduced.

In an effort to reduce the overall length of ALS’s, this report describes the methods, using simulation, by which the minimum visual cues with respect to length of an ALS is needed by pilots during an approach at Category I minimums. The current US standard is the 2400-foot-long Medium Intensity Approach Lighting System with Runway Alignment Indicator Lights (MALSR). Subject pilots evaluated ten different length configurations and were given questionnaires for each configuration flown.

The results indicate that shortening the system to a length of 1600 feet was not acceptable. Shortening the system to a length of 1800 or 2000 feet may be conceivable if enhancements to the visual segment portion of the system (i.e., additional steady-burning barrettes at 1600,1800, and/or 2000 feet) would be considered. Shortening the system to a length of 2200 feet will only provide minimal reduction in ground area required and result in virtually no benefit in reduced equipment or power requirements.

DOT/FAA/AR-02/81
Author: Donald W. Gallagher