Airspeed Indicator Markings

The airspeed indicator restates the airspeed limits in colour, so that a glance at the needle answers the question the numbers answer more slowly. Learn the four markings as ranges with meanings attached, not as decoration on the dial face.

At a glance

• White arc60 – 98 KIAS
• Green arc66 – 130 KIAS
• Yellow arc130 – 172 KIAS
• Red line172 KIAS

What each marking means

The four markings

• White arc, 60 to 98 KIAS — the operating range with the flaps fully extended.

• Green arc, 66 to 130 KIAS — the normal operating range.

• Yellow arc, 130 to 172 KIAS — the caution range, to be used only in smooth air.

• Red line, 172 KIAS — the maximum speed for all operations, v_NE.

Figure: Airspeed indicator markings (redrawn).

Where the arcs overlap

The white and green arcs overlap between 66 and 98 KIAS, which is the band in which the aeroplane may be flown either clean or with the flaps fully out. Below 66 KIAS only the white arc is present; above 98 KIAS the flaps must be in, and the green arc runs on alone to 130 KIAS.

Notice that the top of the green arc, the bottom of the yellow arc and v_NO are all the same 130 KIAS, and that the top of the yellow arc, the red line and v_NE are all 172 KIAS. The dial is telling you the same two limits in a second language.

Check yourself

• What are the lower and upper ends of the white arc, and what does that range represent?

• What speed range does the green arc cover?

• Under what condition may the yellow arc be used?

• At what speed is the red line, and what limit does it correspond to?

• Over what speed range do the white and green arcs overlap?

Study aid — always fly your aircraft's current AFM/POH.