The white PAPI lights (Precision Approach Path Indicator Lights) is a key visual navigation device for aviation safety. Its core function is to provide pilots with intuitive and real-time glide path guidance to ensure that the aircraft lands safely at the correct angle and altitude.
The Core Function of PAPI Lights
- 1. Accurately guide the glide path
The airport PAPI lights use a combination of red and white light to intuitively display the position of the aircraft relative to the ideal glide path (usually 3°), helping pilots to adjust the altitude in time to avoid dangerous approaches.
- 2. Enhance landing safety
In low visibility, at night or in complex weather conditions, PAPI airport lights provide pilots with reliable visual references, reduce human judgment errors, and reduce the risk of landing accidents.
- 3. Global standardization & strong adaptability
Airports around the world use a unified PAPI light signal standard to ensure that pilots can quickly understand and respond correctly no matter where they fly.
- 4. Economical, efficient, stable & reliable
Compared with complex electronic glide slope systems, white PAPI lights have low maintenance costs and low failure rates, and are suitable for all types of airports, including small runways in remote areas.
What do 4 White PAPI Lights Mean?
Precision Approach Path Indicator Lights are usually composed of 4 light units, and their color combination directly reflects the relationship between the aircraft and the ideal glide slope. Among them, 4 white lights (all white) are one of the most noteworthy states, and their meanings are as follows:
4 white PAPI airport warning lights (⚪⚪⚪⚪)-the aircraft is far above the glide slope:
- When the pilot sees 4 white lights, it means that the aircraft’s approach angle is too high, far above the standard glide slope (usually >3.5°).
- At this time, the aircraft may face the following risks:
- Landing distance is too long: Too high a glide angle may cause the aircraft to touch down in the middle or end of the runway, increasing the risk of running off the runway.
- Risk of hard landing: The pilot may need to significantly adjust the pitch attitude to reduce the altitude, which may result in a hard landing.
- Critical period for go-around decision: If the altitude cannot be lowered in time, the pilot should decisively perform a go-around to ensure safety.
Pilot Response Measures:
- Appropriately reduce thrust and increase the descent rate
- Check the matching of altitude and speed
- If it cannot be corrected in time, a go-around should be performed
Recommendation of Professional PAPI Lights
For PAPI light systems that require high precision and high reliability, YFFY Lights’ Precision Approach Path Indicator (PAPI) Light is recommended.
This product complies with the standards of the International Civil Aviation Organization (ICAO) and has the advantages of high-brightness
LED light source, strong weather resistance, and low power consumption, and is suitable for various airport environments.
Airport Precision Approach Path Indicator Lights are key equipment to ensure flight safety, and the four white lights (all white) are important signals to warn that the aircraft is too high.
Pilots must adjust or perform a go-around in time. Correctly understanding white PAPI light signals can greatly improve the safety of approach and landing and reduce aviation accidents caused by human errors.
