ACS tolerances

The Private Pilot Airplane ACS (FAA-S-ACS-6C, effective May 31, 2024) anchors power-off stall tolerances around recognition of the first indication, the recovery technique (reduce AoA → power → wings level), and minimum altitude loss during the recovery.

The tolerances at a glance

Parameter	Target	Tolerance	Reference
Bank during entry	Straight ahead OR up to 20°	±10° in turning entry	VII.B.S2
Recognition	First indication of stall	Verbal announcement	VII.B.S3
Recovery technique	Reduce AoA → power → wings level	Correct sequence	VII.B.S4
Altitude loss	Minimum consistent with recovery	No prescribed ceiling	VII.B.S4

Plus structural requirements:

• Clear the area before beginning — VII.B.S1
• Establish the landing configuration and airspeed — VII.B.S1
• Induce the stall smoothly (no abrupt pitch input) — VII.B.S2
• Recognize and announce the first indication — VII.B.S3
• Recover using the AoA-first sequence — VII.B.S4

Bank during entry

VII.B.S2 specifies the stall may be induced straight ahead or in a 20° banked turn. Both forms are typically demonstrated on a checkride. The turning entry adds:

• Higher accelerated stall speed (V_S × √n; at 20° bank, n = 1.06 — only 3% higher than wings-level).
• Asymmetric drop if the airplane is uncoordinated — one wing stalls first.

The ±10° tolerance on bank applies during the turning entry — the pilot must hold a consistent bank angle through the stall.

Recognition — verbal announcement required

VII.B.S3 requires the pilot to announce the first indication. Recognition is half of the standard; announcement is the other half. Silent recovery isn't a passing demonstration even if mechanically correct.

The DPE wants to hear "Stall warning" or "Stall" as the cue appears.

Recovery technique

VII.B.S4 specifies the recovery as reducing AoA, applying power, and minimizing altitude loss. The order matters and reflects the modern stall-recovery doctrine:

1. Reduce AoA (forward pitch input).
2. Apply power (throttle full forward).
3. Level wings (coordinated aileron + rudder).
4. Recover to climb while minimizing altitude loss.

Reversing the order — adding power first while still pulling — keeps the wing stalled and doesn't recover the airplane.

Altitude loss — minimum, not zero

VII.B.S4 says minimize altitude loss — it doesn't publish a numerical floor. The standard is "the smallest altitude loss consistent with proper recovery." Trying to limit altitude loss by pulling through the recovery re-stalls the wing and is a worse bust than a normal recovery with 200 ft of altitude loss.

In practice, a clean recovery in a typical trainer costs 100–300 ft. The DPE evaluates the technique and the proportional altitude loss, not a fixed number.

The standard is recovery quality, not stall avoidance. The maneuver requires you to enter the stall fully — feel the break, see the nose drop, hear the buffet — then recover. Pulling out before the stall fully develops isn't a passing demonstration; it's avoiding the maneuver.