The heliport approach path indicator (CHAPI) provides the pilot with a safe and accurate glide slope on final approach to the helipad. A row of CHAPI light housing assemblies (LHAs) placed perpendicular to the approach path are seen by the pilot in combinations of red, green, and white to indicate a path that is too high, too low or correctly on slope.

The CHAPI system has a filter inserted between the white and red filters of each lens to provide a 2° wide green sector that, when visible from both units, signals the proper glide slope angle of 6°. Angle deviations that are too high show one or two white lights, and those that are too low show one or two red lights.

Configuration Options
The L-881 CHAPI uses only two LHAs and provides simplified glide slope information. The L881 can be configured to read white/green/red for use on heliports. The LHAs use either 2 lamps (ZA757) or 3 lamps (ZA737). The 3 lamp configuration permits normal operation with one lamp out.

Power Options
CHAPIs are available in two energy styles:
Style A operates from a 240VAC (120V is also available), single phase, 60 Hz power supply. 120V and 50Hz are also available.
Style C is a 12V system powered by auto batteries. This style is of particular value on remote airstrips where it would be uneconomical to bring in power lines.

Operating Conditions
CHAPIs are manufactured to meet two temperature standards: Class I for normal operation to as low as -35° C, and Class II, with lens heaters, for temperatures to -55° C.

Photometrics
Flight Light/ALSTOM CHAPIs have the most reliable photometrics in the industry. On a normal day a
2-lamp CHAPI unit is visible from over 10 miles out. Light distribution curves far exceed FAA requirements.

For FAA style units, a tilt-switch in each CHAPI shuts down the entire system if any unit becomes misaligned.

Technical Specifications
FAA AC NO 150/5345-28
ICAO Annex 14 Fig. 2.20
Installation and Maintenance
Manual: Style A (17-PAPI-AIM)

Performance Advantages
• Outstanding photometric performance. Pilots say they see this CHAPI before they see any competing brand.
• Four-leg design makes each light housing assembly very stable, resulting in fewer shut-downs for realignment thereby reducing maintenance and increasing airfield utilization. (EMT legs not included with domestic orders.)
• LED indicator identifies tilt switch circuit fault.
• Quartz halogen average rated lamp life is 1200 hours! Competitor’s lamps rated at only 1000 hours.

Maintenance Advantages
• Dust proof LHA is standard. Enhances lamp life, improves photometric performance and reduces maintenance cost.
• No optical bench or special tools required for servicing. Special access doors speed lamp changes in the field.
• Off-the-shelf lamps reduce life-cycle costs.
• Circuit breaker and on/off switch in power adapter (Style A) protect equipment at all times.
• Extremely reliable power adapter features WAGO terminal blocks, gas-tight ferrelled connections and Teflon wire.

Options
• Custom configured remote control uses radio modems instead of hard wiring to control CHAPIs.
• Aiming device simplifies setting tilt switch and azimuth angles.
• Interlock relay to operate CHAPI in conjunction with runway lights.
• ICAO version (no tilt switch)
• Field setup and alignment training by Flight Light technicians.
• International packing - four 2" EMT legs per LHA with all units and hardware double boxed.