What Are the Color-Coded Arcs on the Airspeed Indicator and What Do They Represent?

Why Your Airspeed Indicator Is a Color-Coded Safety System

The airspeed indicator is one of the most information-dense instruments in the cockpit. Unlike a simple speedometer, it uses a deliberate system of color-coded arcs and radial lines to communicate structural limits, aerodynamic boundaries, and safe operating ranges at a glance. For your private pilot checkride, your designated pilot examiner (DPE) will almost certainly ask you to explain what each color means — and a vague answer will not cut it. This question comes straight from Chapter 8 of the Pilot's Handbook of Aeronautical Knowledge (PHAK), FAA-H-8083-25, and it rewards candidates who know not just what the colors are, but what the underlying speeds represent and why they matter in real flight.

Breaking Down Each Arc: From White to Red

Start with the white arc, which runs from the bottom of the instrument up to a speed marked VFE — the maximum flap extended speed. The lower limit of the white arc is Vs0, your aircraft's stall speed in the landing configuration, meaning full flaps and gear down if applicable. The entire white arc represents the safe flap operating range. Whenever you are flying with flaps extended, you need to be within this arc. One of the most common errors students make is believing the white arc represents normal operations — it does not. It is specifically and exclusively about flap operations. Exceeding VFE with flaps deployed risks structural damage to the flap hinges and the airframe.

The green arc is the one you will spend most of your flight inside. It spans from Vs1 — stall speed in the clean configuration, meaning flaps and gear up — to VNO, the maximum structural cruising speed. This range is your normal operating envelope. In smooth air, in turbulence, in climbs and descents, the green arc is where your aircraft is designed to be flown routinely. Think of it as your everyday highway. Vs1 at the bottom of the green arc and Vs0 at the bottom of the white arc are two distinct speeds, and confusing them is a mistake that will cost you credibility in front of your examiner.

Above the green arc lies the yellow arc, which extends from VNO up to VNE — the never-exceed speed. This caution range is frequently misunderstood. Flying in the yellow arc is not absolutely prohibited, but it comes with a critical condition: you may only operate here in smooth air. In turbulent conditions, the additional gust loads combined with high indicated airspeed can stress the airframe beyond its design limits. The yellow arc is a warning, not a wall — but treat it with respect. Students who tell their examiner the yellow arc means the aircraft will immediately break apart are just as wrong as those who think it is perfectly routine to cruise there in bumpy air.

Finally, the red radial line at the top of the yellow arc marks VNE. This speed must never be exceeded under any circumstances, in any conditions. Exceeding VNE can lead to catastrophic structural failure. There is no asterisk, no exception for smooth air. It is the hard limit of the airframe's certified envelope.

The Blue Line and a Note on Multi-Engine Aircraft

If you happen to be flying a multi-engine aircraft — or if your examiner wants to probe your broader systems knowledge — you may also encounter a blue radial line on the airspeed indicator. This marks Vyse, best single-engine rate of climb speed, sometimes called 'blue line' by multi-engine pilots. It represents the airspeed that gives the best climb performance when one engine has failed. While this line is not relevant to single-engine private pilot training, knowing it exists demonstrates a well-rounded understanding of the instrument.

How to Talk About This on Your Checkride

When your examiner asks about the airspeed indicator arcs, the goal is not just to recite colors and abbreviations — it is to demonstrate that you understand how these limits connect to real aerodynamic and structural principles. Know that VNO is the top of the green arc and the bottom of the yellow arc, while VNE is the red line. These two speeds are close together on the instrument but represent fundamentally different thresholds: one is the boundary of normal operations, the other is the absolute limit of the airframe. Mixing them up is one of the most common mistakes students make, and examiners notice immediately.

Practice answering this question by physically pointing to each arc on the POH or instrument diagram for your training aircraft and stating the specific speed values — not just the color names. Knowing that the Cessna 172S has a VNO of 129 knots and a VNE of 163 knots is far more impressive than a generic answer. The PHAK gives you the framework; your Pilot's Operating Handbook gives you the numbers. Use both.

If you want to practice questions like this in a realistic oral exam format, try SimulatedCheckride.com.