What is the maximum stall speed allowed for a light-sport aircraft?

Under the FAA's definition in 14 CFR Part 1 and the applicable ASTM standards, a light-sport aircraft must have a maximum stall speed of no more than 45 knots calibrated airspeed (KCAS) in the clean configuration, with power off, at maximum certificated gross weight. This limit is a certification requirement and helps reduce the energy involved in stall-related accidents. The actual stall speed of a specific LSA in any given flight condition may be lower or — in banked turns or at higher weights — effectively higher than this baseline.

How does bank angle affect stall speed in an LSA?

Banking an aircraft increases load factor because only part of the wing's total lift acts vertically to support the aircraft's weight. To maintain altitude, the pilot increases back pressure, raising the angle of attack closer to the critical AOA and effectively increasing stall speed. At a 60-degree banked turn, the load factor doubles to 2 G and stall speed rises by approximately 41 percent above the wings-level value; even a 45-degree bank raises stall speed by about 19 percent. This is why the base-to-final turn in the traffic pattern is one of the most hazardous phases of flight for stall/spin accidents.

Why does stall speed stay the same on the airspeed indicator at high altitude even though true airspeed is higher?

The airspeed indicator measures dynamic pressure, which is directly related to the aerodynamic forces the wing experiences. Because a wing always stalls at the same critical angle of attack, it stalls at the same dynamic pressure — and therefore the same indicated airspeed — regardless of altitude. However, at high density altitude the air is less dense, so the same dynamic pressure corresponds to a much higher true airspeed and groundspeed. Pilots must account for this when planning runway requirements and obstacle clearance at high-elevation airports, even though the airspeed indicator reads the familiar stall speed.

Stall Characteristics & Stall Speed in Light-Sport Aircraft

Every wing produces lift by redirecting airflow over its upper and lower surfaces. As a pilot increases the angle of attack (AOA) — the angle between the wing's chord line and the relative wind — lift climbs steadily, reaching a maximum at the critical angle of attack. Beyond that point, the smooth, attached airflow over the upper surface separates violently, the pressure differential collapses, and lift drops faster than drag rises. The wing stalls. This is the foundational truth of stall aerodynamics, and no other concept matters more for light-sport pilots: a stall is always and exclusively caused by exceeding the critical angle of attack, regardless of airspeed, attitude, power setting, or weight. A light-sport aircraft (LSA) can enter a full stall while banked steeply at a surprisingly high indicated airspeed, or while climbing under full power, just as readily as it stalls in level slow flight. Understanding why — and what moves the stall speed up or down — is central to both the FAA Sport Pilot Knowledge Test and real-world safety.

The LSA Stall Speed Limit: What 45 KCAS Really Means

The FAA and ASTM International standards that define the light-sport aircraft category impose a firm ceiling: the maximum stall speed in the clean configuration, power off, at maximum certificated gross weight must not exceed 45 knots calibrated airspeed (KCAS). This limit appears in 14 CFR Part 1 (definitions) and Part 61 (Sport Pilot privileges) as a defining characteristic of the category. It is not arbitrary — it directly caps the kinetic energy involved in a stall or stall/spin accident, reducing impact severity and giving a low-time pilot a slightly wider margin for recovery.

The 45-knot figure is a regulatory maximum for aircraft certification, not a universal stall speed that applies to every flight. The actual stall speed your specific aircraft will exhibit on any given flight depends on configuration, loading, and maneuvering. The aircraft's Pilot's Operating Handbook (POH) or Flight Manual contains the authoritative stall speeds for various configurations — and even those published numbers are baseline values measured at max gross weight in controlled test conditions. Understanding how real conditions depart from those baselines is what separates a knowledgeable pilot from one who relies on a single memorized number.

Airspeed Indicator Color Coding and Stall Reference Speeds

The standard airspeed indicator in most LSAs uses color-coded arcs to communicate stall reference speeds at a glance. Two speeds are most important:

VS0 — stall speed in the landing configuration (flaps fully extended, gear down if applicable, power off). This is the lower number and marks the bottom of the white arc.
VS1 — stall speed in a specified configuration, most commonly clean (flaps up). This marks the bottom of the green arc.

Because flaps increase camber and generate more lift at a given AOA, the aircraft can fly slower before stalling in the landing configuration — so VS0 is always lower than VS1. Extending flaps on final approach is not just about increasing drag for a steeper descent; it genuinely lowers the stall speed and widens the margin between approach speed and the stall.

Factors That Change Stall Speed: A Detailed Look

Weight and Load

Lift must equal weight in steady, level, unaccelerated flight. A heavier aircraft requires more lift. At any given angle of attack, the only way to generate more lift is to fly faster. Therefore, a heavier aircraft reaches its critical AOA — and stalls — at a higher airspeed than a lighter one with identical aerodynamics. For practical flying, this means a fully-loaded LSA at max gross weight will stall noticeably faster than the same aircraft flown solo with no baggage. The FAA's PHAK (FAA-H-8083-25) describes the relationship between weight and stall speed using a square-root proportion: stall speed scales with the square root of the weight ratio. If you carry only 75% of max gross weight, stall speed decreases by roughly 13%. Conversely, exceeding the max gross weight — which is illegal and dangerous — raises stall speed above the POH-published value.

Bank Angle and Load Factor

This is the factor that surprises the most pilots. When an aircraft banks, total lift must be divided into a vertical component (supporting weight) and a horizontal component (providing the centripetal force for the turn). To keep the vertical component equal to weight, total lift must increase — and that requires either more speed or a higher angle of attack. In a coordinated 60° banked turn, the load factor reaches 2.0 G, and the stall speed increases by approximately 41% above the wings-level value. A clean stall speed of 40 KCAS becomes roughly 56 KCAS in that 60° bank. Even a 30° bank produces a load factor of about 1.15 G, raising stall speed by roughly 7%. The practical danger zone is the traffic pattern: a low, slow, coordinated turn from base to final with even modest bank angles can push stall speed up to or past the approach speed, especially if the turn is rushed and back pressure is applied.

Flap Configuration

Extending flaps increases wing camber and, for partial flap settings, wing area. Both effects increase the coefficient of lift at any given AOA, allowing the wing to generate the same lift at a lower airspeed. The result is a lower stall speed in the flaps-extended configuration compared to the clean configuration. This is why the white arc on the airspeed indicator (the flap-operating range) begins at the lower VS0 speed. In the traffic pattern, using the recommended flap setting for approach gives the pilot a genuine aerodynamic buffer — the stall speed is legitimately lower, not just the indicated approach speed.

Power Effects

Power influences stall speed in two ways. First, thrust has a direct vertical component in nose-high attitudes, partially supporting the aircraft's weight and reducing the lift the wing must generate. Second, propeller slipstream accelerates the airflow over the inboard wing sections, increasing the effective dynamic pressure there and delaying local flow separation. Together, these effects make power-on stalls occur at a lower indicated airspeed than power-off stalls. A pilot who exclusively practices power-off stalls may be unprepared when a full-power departure stall breaks at an airspeed well below the expected clean stall speed shown in the POH.

Density Altitude

Density altitude does not change the indicated airspeed at which a stall occurs — the wing stalls at the same indicated airspeed (IAS) regardless of altitude, because IAS reflects dynamic pressure, which is what the wing actually experiences. However, at high density altitude, the same indicated airspeed corresponds to a much higher true airspeed (TAS) and groundspeed. An LSA approaching a high-elevation airport at 55 KCAS indicated is covering the ground significantly faster than the same IAS at sea level. Runway length requirements and obstacle clearance margins increase accordingly, even though the stall margin on the airspeed indicator looks identical.

Key Numbers and Rules to Memorize

LSA maximum stall speed: 45 KCAS, clean, power off, at max gross weight.
VS0 = bottom of white arc (landing configuration stall speed).
VS1 = bottom of green arc (clean configuration stall speed).
Load factor at 60° bank: 2.0 G; stall speed increase: approximately 41%.
Load factor at 45° bank: approximately 1.41 G; stall speed increase: approximately 19%.
Load factor at 30° bank: approximately 1.15 G; stall speed increase: approximately 7%.
Critical AOA for most general aviation wings: approximately 15–20° (varies by airfoil; exact value is airfoil-specific).
Stall speed scales with the square root of the load factor: VSbank = VSlevel × √(load factor).

Common Test Traps

"A stall happens only at low airspeed." Completely false. Exceed the critical AOA at any speed — high or low — and the wing stalls. Abrupt back pressure at high speed in a dive recovery can produce a high-speed stall.
Confusing VS0 and VS1. VS0 is the landing configuration stall speed (white arc bottom); VS1 is the clean or specified configuration stall speed (green arc bottom). They are not interchangeable.
Assuming 45 KCAS is the stall speed in all conditions. It is the regulatory maximum for certification at max gross weight, clean, power off. Actual stall speed in a banked, loaded, flaps-up situation may be higher. Always use the POH stall speed tables.
Thinking power-on stall speed equals power-off stall speed. Power-on stalls typically occur at a lower IAS. A pilot surprised by this may over-rotate during a go-around and enter an inadvertent stall.
Ignoring the base-to-final turn. This low-altitude, low-speed, often-hurried maneuver is one of the deadliest scenarios in light aviation. Even a 30–45° banked coordinated turn meaningfully raises stall speed above the wings-level POH figure.

Memory Aid

To recall the factors that raise stall speed above the published baseline, use WBCP: Weight increased, Bank angle increased, Clean configuration (flaps up), Power off. When any of these conditions shift in the opposite direction — lighter weight, wings level, flaps extended, power applied — stall speed decreases from the baseline. Apply this checklist mentally before every slow-flight or approach phase and you will rarely be caught off guard by an unexpected stall margin.

Stall Characteristics and Stall Speed in Light-Sport Aircraft