Systems – Airspeed Indicator | Training Blog

What Do the Colored Markings on an Airspeed Indicator Mean

An airspeed indicator does more than display indicated airspeed (IAS).

It also provides important visual cues that help pilots operate the aircraft safely throughout every phase of flight.

These colored markings identify speed ranges where certain operations are permitted—or prohibited—and understanding them is essential for safe aircraft operation.

While the exact airspeeds vary from one aircraft to another, the meaning of each colored arc remains the same.

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✈️ Why This Matters (Performance + Structural Safety)

The colored markings on the airspeed indicator help pilots:

• Operate within the aircraft's structural limits
• Use flaps safely
• Avoid excessive aerodynamic loads
• Recognize when turbulence requires slower airspeeds
• Prevent overspeed damage

​Every colored arc represents a limitation established during aircraft certification—not merely a recommendation.

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🎯 The Four Primary Airspeed Marking
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⚪ White Arc — Flap Operating Range
The white arc represents the speed range in which the wing flaps may be safely operated.

Lower Limit: Vso
Stall speed in the landing configuration (typically with full flaps).

Upper Limit: Vfe
Maximum flap extended speed.
Flying above Vfe with the flaps extended may result in structural damage to the flap system.

The white arc is commonly used during:

• Approach
• Landing
• Go-arounds
• Short- and soft-field operations

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🟢 Green Arc — Normal Operating Range
The green arc represents the normal operating speed range for the aircraft.

Lower Limit: Vs1
Stall speed in a specified (clean) configuration.

Upper Limit: Vno
Maximum structural cruising speed.

Within the green arc, the aircraft may be operated normally in both smooth and moderately turbulent air.

This is where the airplane spends most of its time during cruise flight.

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🟡 Yellow Arc — Caution Range
The yellow arc is the caution range.

Aircraft should be operated in this range only in smooth air and with caution.

Because aerodynamic loads increase rapidly with speed, turbulence encountered in the yellow arc can create structural loads beyond the aircraft's design limits.

The closer you get to the red line, the smaller your safety margin becomes.

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🔴 Red Line — Never Exceed Speed (Vne)
The red radial line marks:

Vne — Never Exceed Speed
This is the maximum permissible airspeed.

Operating above Vne may result in:

• Structural failure
• Control surface flutter
• Loss of aircraft control

Unlike the yellow arc, there are no conditions under which intentional flight beyond the red line is permitted.

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🛩 Operational Scenarios

Scenario 1
You're established on final approach with full flaps.
You notice IAS increasing above Vfe.

What should you do?

Reduce airspeed promptly while maintaining aircraft control.
Flaps are not designed to withstand speeds above their operating limit.

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Scenario 2
You're cruising on a calm day near Vno.
Unexpected moderate turbulence develops.

Should you remain at the same airspeed?

No.
Reduce airspeed into the green arc to decrease structural loading caused by gusts.

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Scenario 3
You're descending from altitude.
The airplane continues accelerating toward the red line.

Why is this dangerous?

Exceeding Vne can lead to structural failure or control surface flutter, even if the airplane appears to be flying normally.

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⚠️ Common Training Mistakes

• Thinking the colored arcs are only for checkrides
• Confusing Vs1 with Vso
• Believing the yellow arc is simply a "higher cruise speed"
• Assuming Vne provides a safety buffer
• Ignoring turbulence while operating near Vno

The colored markings aren't suggestions—they're operating limitations.

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🧩 The Big Takeaway

The airspeed indicator provides more than airspeed information.

Its colored markings help pilots safely operate the aircraft throughout every phase of flight.

White Arc: Flap operating range (Vso to Vfe)
Green Arc: Normal operating range (Vs1 to Vno)
Yellow Arc: Caution range—smooth air only
Red Line: Never exceed speed (Vne)

Understanding these markings helps protect both the airplane and its occupants by keeping operations within the aircraft's certified design limits.

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🗓 Next Week

Weather – Nonstandard Temperature

What effect does nonstandard temperature have on altimeter readings?

Next week, we'll explore how temperatures warmer or colder than the standard atmosphere affect your true altitude—even when your altimeter appears to be indicating correctly.

​We'll explain why pilots remember the saying, "From High to Low, Look Out Below," and discuss how cold temperatures can place an aircraft significantly lower than its indicated altitude. Understanding this relationship is especially important when operating near terrain, obstacles, or on instrument approaches.