VASI Lights

VASI Lights

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VASI lights are used in SIM mode or during flight.


4 Red Lights Below Glidescope Level, before glidescope intercept	3 Red Lights, 1 White Light Approaching glidescope


2 Red Lights, 2 White Lights This indicates that the plane is on glidescope.	1 Red Lights, 3 White Lights Slightly above glidescope, increase descent rate

0 Red Lights, 4 White Lights
Above glidescope

VASI (Visual Approach Slope Indicator) lights appear in the lower left corner of the map when on approach to the destination runway. This is a computed 3 degree descent glideslope that crosses 50 feet above the runway threshold.

Four white lights - indicate that you are above glidescope.

One red and three white lights - indicate that you are slightly above glidescope.

Two red lights over two white lights - indicate that you are on glideslope.

Three red lights and one white light - indicate that you are slightly below glidescope.

Four red lights - indicate that you are below glidescope.

The altitude displayed next to the VASI lights is the computed glideslope altitude for the current distance from the runway. Your altimeter reading should be close to this value. The computed VASI display is affected by the GPS altitude errors. The computed glideslope altitude is more precise than your altimeter!

The first VASI screenshot shows that the computed glideslope works around corners. The total distance to the runway is used to compute the 3 degree glideslope. This gives no obstruction clearance protection and is to be used for planning a visual approach. An instrument approach would have protected areas around the approach path and minimum crossing altitudes at waypoints.

You might enjoy using SIM mode with the VASI approach system. Use the rocker switch to adjust altitude to "fly" the simulator. Use hardware button 3 to accelerate and button 4 to decelerate. Make an aircraft profile that has appropriate speeds and altitude for the simulated flights.

GPS altitude is not to be trusted. In flight, the VASI display indicates you should not be looking at the map, you should be landing the plane! Compare the GPS ALT display to your altimeter in flight to see the difference. GPS systems certified for approaches require a barometric pressure altitude signal.