The Helicopter Approach Path Indication (HAPI) system is designed for airports and airstrips to determine the correct approach path of a landing helicopter. The angle of the system is adjusted using the built-in monitor. The design is available in three basic models with various configuration options, in accordance with the International Civil Aviation Organization (ICAO). The model of this lighting unit with built-in LED module and lens system emits four different types of light:

• Flashing green light: helicopter above the optimal approach slope (too high),
• steady green light: helicopter on the slope,
• Flashing red light: helicopter below optimal pitch (too low),
• constant red light: helicopter slightly below optimal pitch (slightly too low)

Depending on the position of the aircraft on the approach path, and thus the angle of observation of the device, the pilot, observing one of the above four signals, can correct the trajectory of the aircraft on the approach
path.