The Yellow Arc

Tuesday, November 22, 2022 at 10:52 AM ET

Verified

The two main airspeed presentations found in piston-powered airplanes are shown: a generic “round-dial” airspeed indicator with a prominent yellow arc and a zoomed-in image of a Garmin G1000’s airspeed tape.

Key Takeaways:

The yellow arc (caution range) on a piston-powered airplane's airspeed indicator signifies a speed regime (V_NO to V_NE) where structural protection against gusts and abrupt control inputs is significantly reduced.
Aircraft in the yellow arc are only certified to withstand a 15 fps gust, half the 30 fps gust tolerance of the green arc, making them highly susceptible to airframe damage from moderate turbulence or significant control inputs.
Pilots should fly in the yellow arc only with extreme caution, ensuring predictably smooth air and maintaining essentially neutral flight controls, due to the increased risk of structural damage and potential for cumulative fatigue over time.

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Look at an airspeed indicator or vertical speed tape, as below, in a piston-powered airplane and you’ll see a yellow range of indicated speeds. This is called the “caution range.” Since typical piston airplanes can’t cruise in this speed range under most circumstances, we often don’t spend a lot of time learning how very different the airframe overstress protection scheme is when operating in the yellow arc instead of the green one. It’s not like the FAA decided to spice up airspeed indicators with a splash of color: There is a very real reason for the caution range of the airspeed indicator.