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Electronic Flight Instrumentation for Experimental Aircraft Since 1991

Altitude Intercept Arc

The Altitude Intercept Arc appears as a variable green arc on the map screen of Sport and Horizon series EFIS systems.

What is it?

It is a visual depiction of the place the aircraft will be when it intercepts the altitude entered into the altitude preselect window, or “altitude bug.” It’s calculated using the current rate of climb or descent and groundspeed.  Airline pilots sometimes call this arc “the banana.”

How do I use it?

During a climb or descent, adjust the rate of altitude change to place the arc over the place you want to be when you get to your selected altitude. This can be very useful in a cruise descent toward your destination if you set the altitude bug to pattern altitude or your next IFR altitude. It can also be useful for planning climbs near high terrain. The more stable the descent or climb, the more stable the arc will be. It shrinks as you get closer to the altitude intercept point.