ACS tolerances

The Private Pilot Airplane ACS (FAA-S-ACS-6C, effective May 31, 2024) anchors instrument-climb tolerances around airspeed, heading, and level-off precision at the target altitude. The tolerances mirror straight-and-level (VIII.A) on heading and airspeed; the altitude tolerance is reframed as a level-off precision because the maneuver is climbing.

The tolerances at a glance

Parameter	Target	Tolerance	Reference
Climb airspeed	Target (typically V_Y)	±10 KIAS	VIII.B.S2
Heading	Selected heading	±10°	VIII.B.S2
Level-off altitude	Target altitude	±100 ft (level-off precision)	VIII.B.S2

Plus the structural requirement:

• Establish a constant-airspeed climb solely by reference to instruments — VIII.B.S1

Airspeed ±10 KIAS

The climb is constant-airspeed — the pilot holds the target speed throughout the climb. The ASI is primary for pitch in this regime; airspeed drift signals a pitch error before altitude or VSI catches up.

The ACS doesn't specify which target airspeed — typically V_Y for routine climbs. The standard is constant at the target, not "at V_Y specifically." A briefed target of 80 KIAS that's held at 80 ± 5 throughout the climb meets the standard even if V_Y is different.

Heading ±10°

Same as straight-and-level (VIII.A.S2). The HI is primary for bank; small bank corrections handle drift.

In a climb, left-turning tendencies are more active than in cruise (cross-ref to IV.A PRI for the P-factor, torque, accelerated slipstream, spiraling slipstream discussion). Right rudder is actively used to hold heading without bank.

Level-off altitude ±100 ft

This is the climb-specific tolerance. The standard isn't "altitude held during the climb" (altitude is changing — there's no fixed value during the climb). The standard is the level-off occurs within ±100 ft of the target altitude.

A bust pattern:

• Through the target by more than 100 ft (late level-off, momentum carries the airplane past the target).
• Short of the target by more than 100 ft (early level-off, settling at 200 ft below target and unable to recover without another power adjustment).

Anticipation is the prevention: lead the level-off by 10% of the climb rate.

Solely by reference to instruments

VIII.B.S1 requires the maneuver to be flown without external visual references. Same standard as VIII.A.S1; the discipline is identical.

The level-off precision is the new skill. Straight-and-level holds an altitude; the climb tests whether you can hit a target altitude on the way up. Lead by 10%; pitch and power together; verify on the primary altimeter at the new straight-and-level condition.