ACS Task IR.III.A — Compliance with ATC Clearances

What is ACS Task IR.III.A and what does it cover?

IR.III.A falls within Area of Operation III — ATC Clearances and Procedures — of the FAA Instrument Rating ACS (FAA-S-ACS-8C) . The task evaluates three categories of competency: Knowledge, Risk Management, and Skills, all centered on how you receive, interpret, and execute ATC clearances in IFR operations.

This task is evaluated primarily during the oral portion of the checkride. The DPE will issue a simulated departure clearance — often complex, with multiple segments — and evaluate whether you read it back correctly, catch errors, and demonstrate knowledge of deviation authority, void times, and "unable" calls. It is also observed in flight when ATC issues instructions during the practical portion.

What knowledge elements does IR.III.A require?

The ACS identifies three core knowledge areas for this task, all traceable to 14 CFR 91.123 and the AIM:

What does 14 CFR 91.123 actually require?

14 CFR 91.123(a) states that when an ATC clearance has been obtained, no PIC may deviate from it except in an emergency. If a clearance is amended in flight, the pilot must comply with the amended clearance upon receipt unless an emergency exists.

Section (b) is the emergency deviation authority: the PIC may deviate from any rule in Part 91 to the extent necessary to meet an emergency. Critically, the PIC must notify ATC of the deviation as soon as possible. If ATC requests a written report of the deviation, the pilot must submit one. This is a bright-line requirement — deviation without notification is not authorized.

The CRAFT mnemonic: what to read back

AIM 4-4-7 requires pilots to read back ATC clearances so ATC can confirm they were received correctly. The CRAFT mnemonic organizes the mandatory elements:

Every element must be read back verbatim. If ATC corrects your readback, the corrected version is the clearance you must fly. Per AIM 4-4-7(b) , ATC controllers are required to listen to readbacks and correct any errors they hear. A clearance that is not corrected after readback is considered correctly received and accepted.

Additional mandatory readback items

Beyond CRAFT, the following items always require a readback per AIM 4-4-7 :

• ATC-assigned runway for takeoff or landing
• Taxi instructions that include a runway crossing or hold-short instruction
• Any change to your assigned altitude or heading while airborne
• Altimeter settings (when issued as part of an instrument approach clearance)

What are the risk management elements for IR.III.A?

The ACS requires applicants to demonstrate risk management judgment around two scenarios: what to do when you cannot comply with a clearance, and the risks of accepting a clearance you do not fully understand.

When to say "unable"

"Unable" is the correct and required response any time you cannot comply with an ATC clearance — due to aircraft performance limits, equipment failure, weather, or crew workload. Per AIM 4-4-7 , state the reason briefly. ATC will then work to provide an alternative.

Accepting a clearance you cannot or will not comply with is never correct. It creates a false picture of your actual track in the ATC system and may cause traffic separation loss. If you accept a clearance, you are committed to flying it unless an emergency develops.

Void times and their risk

When ATC issues a clearance for departure from an uncontrolled airport, they include a clearance void time — the time by which you must be airborne. Per AIM 5-2-6 , if you do not depart before the void time:

1. 1
   Your clearance is automatically cancelled at the void time.
2. 2
   You must contact ATC within 30 minutes of the void time to advise your intentions.
3. 3
   If ATC does not hear from you within 30 minutes, they may initiate search and rescue.
4. 4
   You may not depart IFR after the void time without a new clearance.

Amended clearances and readback errors

Amended clearances issued in flight require immediate compliance and a full readback of the changed elements. The risk of a partial or missed readback is that you may fly the wrong route, altitude, or frequency without ATC being aware. If ATC does not correct your readback within a reasonable time, request clarification — do not assume silence means the clearance is correct.

What skill elements does the DPE evaluate on IR.III.A?

The ACS Skill element for IR.III.A is direct: the applicant must use correct and concise phraseology when reading back and acknowledging ATC clearances and instructions. "Correct" means verbatim CRAFT readback. "Concise" means no extraneous narrative — standard aviation phraseology only.

The DPE evaluates this in two settings:

1. Oral exam: A simulated clearance is delivered, and you must read it back in real time, catching any errors or discrepancies.
2. In flight: When ATC issues instructions during the practical test, the DPE evaluates your readback, compliance, and timing.

What does the DPE look for on IR.III.A?

DPEs evaluate IR.III.A along these dimensions:

• Verbatim CRAFT readback — all five elements, in order, without paraphrase
• Correct phraseology on 'unable' if the simulated clearance contains an element you cannot accept
• Accurate recall of 91.123(b) emergency deviation authority and the mandatory ATC notification requirement
• Knowledge of void time mechanics and the 30-minute notification window
• Understanding that silence from ATC after readback does not automatically validate a clearance — you must request clarification if uncertain

A common DPE technique: deliberately read back a slightly incorrect altitude during the simulated clearance scenario — then observe whether the applicant catches the DPE's correction and acknowledges the change. This tests whether the applicant is actively listening to ATC responses, not just transmitting.

What are the most common errors on IR.III.A?

• Paraphrasing instead of reading back CRAFT verbatim ('Got it, 4,000 feet' instead of 'Climb and maintain 4,000')
• Omitting the transponder code from the readback — the most frequently dropped CRAFT element
• Confusing the 'expect' altitude as the initial assigned altitude (e.g., treating 'expect 8,000 in 10 minutes' as an immediate clearance to climb)
• Failing to say 'unable' when the simulated clearance asks for something operationally impossible, instead accepting it passively
• Not knowing the 91.123(b) ATC notification requirement for emergency deviations — knowing you 'can' deviate is not sufficient without knowing you must notify
• Stating the void time wrong in the readback — off by even 1 minute is considered an error

Frequently Asked Questions

Q: What items must you always read back on an IFR clearance?

Per AIM 4-4-7, the full CRAFT elements — Clearance limit, Route, Altitude, Frequency, and Transponder code — must be read back verbatim. ATC-assigned runway, taxi instructions, hold-short instructions, and any altimeter setting changes are also mandatory readback items.

Q: Can you deviate from an ATC clearance in an emergency?

Yes. 14 CFR 91.123(b) authorizes the PIC to deviate from an ATC clearance to the extent necessary in an emergency. The pilot must notify ATC of the deviation as soon as possible. If requested by ATC, the pilot must also submit a written report.

Q: What does "unable" mean as an IFR pilot?

Saying "unable" informs ATC you cannot comply with their clearance or instruction — due to aircraft performance, weather, equipment, or other limiting factors. Per AIM 5-3-1, state the reason briefly. ATC will then issue an amended clearance or hold you for a better solution.

Q: What is the difference between a clearance and an advisory?

A clearance is a specific ATC authorization to proceed under stated conditions; compliance is mandatory per 14 CFR 91.123(a). An advisory (traffic, weather, pirep) is informational only — no pilot action is required unless the advisory becomes a clearance or instruction.

Q: What must you do if ATC issues an amended clearance that requires a route change?

Read back the entire amended clearance, including the new route. If the amendment contradicts your filed plan in a way you cannot accommodate, say "unable" immediately and state the reason. Never silently accept a clearance you do not intend to or cannot comply with.

Q: What is a void time and how does it affect clearance compliance?

A clearance void time is a specific clock time assigned by ATC for uncontrolled-airport departures. If you do not depart by that time, the clearance is cancelled. Per AIM 5-2-6, you must advise ATC of your intentions within 30 minutes of the void time or ATC may initiate search and rescue.

Q: How does IR.III.A relate to 14 CFR 91.173?

14 CFR 91.173 requires an IFR clearance before entering controlled airspace. IR.III.A evaluates whether you can properly receive, read back, and comply with that clearance once issued — the two requirements work in sequence: get the clearance (91.173), then execute it correctly (IR.III.A).

Q: What does the DPE specifically look for on IR.III.A during the oral exam?

The DPE will typically deliver a simulated departure clearance and ask you to read it back correctly, then probe your knowledge of 91.123 deviation authority, the "unable" call, void times, and what constitutes a mandatory readback item per AIM 4-4-7.

Sources

• 14 CFR 91.123 — Compliance with ATC Clearances and Instructions (Cornell LII)
• 14 CFR 91.123 — eCFR
• 14 CFR 91.173 — ATC Clearance and Flight Plan Required (Cornell LII)
• AIM 4-4-7 — ATC Clearances and Instructions (FAA)
• AIM 5-2-6 — Departure Procedures: Clearance Void Times (FAA)
• FAA Instrument Rating ACS (FAA-S-ACS-8C)
• FAA Instrument Flying Handbook (FAA-H-8083-15B)

This article was researched from FAA primary sources (ACS, 14 CFR Part 91, AIM) and citing current regulatory text — drafted by MockDPE. Last updated: May 2026. If you spot an inaccuracy, email corrections@mockdpe.org.