ACS tolerances

The Private Pilot Airplane ACS (FAA-S-ACS-6C, effective May 31, 2024) anchors VIII.F tolerances around effective communication and navigation under simulated instrument conditions while maintaining the basic instrument scan. The numerical altitude / heading / airspeed tolerances aren't restated here — the maneuver inherits them from the underlying basic instrument tasks (A, B, C, D).

The tolerances at a glance

Parameter	Target	Tolerance	Reference
Underlying flight tolerances	Altitude ±100, heading ±10°, airspeed ±10 kt	(inherited from VIII.A-D)	VIII.A.S2, B.S2, C.S2, D.S2
ATC communication	Effective use	No specific tolerance	VIII.F.S1
Nav system use	Effective use	No specific tolerance	VIII.F.S1
Automation while scanning	Effective use of automation, scan maintained	No specific tolerance	VIII.F.S2

Plus structural requirements:

• Communicate with ATC and use radio navigation aids effectively — VIII.F.S1
• Demonstrate effective use of automation while maintaining instrument scan — VIII.F.S2

Inherited flight tolerances

The maneuver doesn't suspend the basic instrument tolerances. While managing comm and nav:

• Altitude must stay within ±100 ft of the assigned value.
• Heading must stay within ±10°.
• Airspeed must stay within ±10 KIAS.

A radio call that takes long enough for the airplane to drift outside these tolerances is a bust — on the underlying basic instrument standard, not on the comm task itself.

"Effective" — what the standard means

VIII.F.S1 and S2 use the word "effective" rather than publishing a numerical tolerance. The DPE evaluates qualitatively:

• Does the pilot communicate clearly (callsign, position, request)?
• Does the pilot read back assignments correctly?
• Does the pilot use nav aids correctly (VOR identified, GPS waypoint correct, CDI tracked)?
• Does the automation work in the pilot's favor, not against them?

A pilot who fumbles a transmission can still demonstrate effectiveness if they recover — they're showing they can handle the workload. A pilot who delivers a perfect transmission but loses 200 ft of altitude during it has failed effectiveness even though the radio work was clean.

What the maneuver tests vs. what it doesn't

Tests:

• Workload management between flight, comm, and nav.
• Scan protection during secondary tasks.
• Pre-briefed and ad-hoc radio work.
• Effective automation use.

Doesn't test:

• Specific ATC procedures (read-back, clearances) at IFR-rating depth — those are CFII content.
• Detailed GPS programming (waypoint entry, approach loading) — basics only.
• Autopilot programming or troubleshooting beyond basic use.

The maneuver is PPL-appropriate: it confirms the pilot can handle modest workload under simulated instrument conditions, not that they have IFR-level proficiency.

The scan is the standard the standard rides on. Every "effective" judgment by the DPE depends on the underlying flight tolerances being met. A pilot who lets the airplane drift while communicating has failed the maneuver regardless of how well the radio call went. The discipline: protect the scan first, manage the secondary task in increments.