1. Understanding an IFR Clearance

An ATC clearance authorizes an aircraft to operate under specified conditions. It may establish the aircraft’s route, altitude, departure procedure, or clearance limit.

A standard IFR clearance can be organized using the acronym CRAFT:

Consider this example of a simulated clearance:

“Cleared to Prescott Airport via radar vectors, then as filed. Climb and maintain 5,000, expect 7,000 ten minutes after departure. Departure frequency 120.7, squawk 4621.”

The pilot must understand each component before accepting the clearance and configure the aircraft accordingly.

Important: An altitude identified as “expect” is not authorization to climb to that altitude. The pilot must maintain the assigned altitude until receiving further authorization, except when applicable lost communication procedures require otherwise.

2. Pilot Responsibilities and Clearance Compliance

Once an ATC clearance has been accepted, the pilot is expected to comply with its instructions unless an amended clearance is obtained or an applicable exception permits deviation.

Pilots are responsible for:

• Accurately copying and acknowledging clearances.

• Reading back critical instructions.

• Requesting clarification when instructions are unclear.

• Maintaining assigned headings, altitudes, and routes.

• Advising ATC when unable to comply with an instruction.

• Requesting amended clearances when operational circumstances require a change.

A clearance does not authorize a pilot to violate an applicable regulation, disregard aircraft limitations, or operate the aircraft unsafely.

For example, if ATC assigns a climb gradient that exceeds the aircraft’s performance capabilities, the pilot should advise ATC and request an alternative rather than accept an instruction the aircraft cannot safely accomplish.

The pilot in command retains responsibility for the safe operation of the aircraft.

3. Clearance Readbacks and Effective Communication

Accurate communication reduces the risk of altitude deviations, navigation errors, and misunderstandings between pilots and controllers.

Pilots should use standard aviation phraseology and read back critical clearance elements, including assigned altitudes, headings, runway hold-short instructions, and other instructions as appropriate.

A useful communication sequence is:

Listen → Copy → Understand → Read Back → Verify → Execute

Before acting on a clearance, confirm that it was issued to your aircraft, particularly when another aircraft has a similar call sign.

If a clearance is incomplete, unclear, or inconsistent with the aircraft’s capabilities, request clarification immediately.

Pilots should avoid making assumptions about ATC’s intentions.

4. Amended Clearances and IFR Route Changes

IFR clearances may change during flight because of traffic, weather, airspace restrictions, or operational requirements.

An amended clearance may include:

• A new heading or route.

• An altitude change.

• Direct navigation to a waypoint.

• A different arrival or instrument approach.

• Revised speed restrictions.

When receiving an amended clearance, pilots should verify the new instructions, update the appropriate navigation equipment, and confirm that the aircraft is following the revised clearance.

For GPS-equipped aircraft, particular attention should be given to verifying the active waypoint, selected navigation source, and flight plan sequencing.

Risk management consideration: Avoid allowing avionics programming to interfere with aircraft control. When necessary, request vectors or additional time from ATC to safely manage the change.

5. Clearance Void Times and Departure Procedures

At airports without an operating control tower, pilots may receive an IFR departure clearance containing a clearance void time.

A clearance void time establishes the time by which the aircraft must be airborne for the clearance to remain valid.

Pilots must understand the difference between:

• Release time: The earliest time the aircraft is authorized to depart under the clearance.

• Clearance void time: The time after which the aircraft is no longer authorized to depart using that clearance.

• Hold for release: An instruction prohibiting departure until ATC provides a release.

If the aircraft cannot depart before the clearance void time, the pilot must not depart under that clearance and must obtain further authorization.

Pilots should also understand the applicable notification requirements if a departure is not completed.

6. Lost Communication Procedures

A radio failure during IFR operations requires pilots to apply established procedures while maintaining aircraft control and situational awareness.

When operating in instrument meteorological conditions, pilots must determine the appropriate route and altitude based on the last clearance, ATC instructions, and applicable regulations.

Two commonly used memory aids are:

AVEF — Route Priority

MEA — Altitude Selection

Fly the highest of the following applicable altitudes for the route segment:

• Minimum IFR altitude.

• Expected altitude advised by ATC.

• Assigned altitude in the last clearance.

If operating in VFR conditions after a two-way radio failure, the applicable regulation generally requires the pilot to continue under VFR and land as soon as practicable.

Lost communication procedures also require understanding clearance limits, expected further clearance times, and approach initiation requirements.

7. Emergency Authority and ATC Coordination

An emergency may require a pilot to deviate from an ATC clearance to protect the aircraft and its occupants.

The pilot in command has the authority to take necessary action when an emergency requires immediate attention.

Examples may include:

• An engine failure requiring an immediate diversion.

• Severe icing that prevents maintaining an assigned altitude.

• An equipment malfunction affecting navigation or aircraft control.

• Hazardous weather requiring an immediate course change.

When circumstances permit, advise ATC of the emergency, describe the assistance needed, and communicate any necessary deviations.

Aviate, navigate, communicate remains the appropriate priority when managing an emergency.

8. Practical Checkride Preparation

During the Instrument Rating practical test, applicants should be prepared to receive, interpret, and comply with actual or simulated ATC clearances while operating by reference to instruments.

The examiner may evaluate the applicant’s ability to:

• Copy and accurately read back clearances.

• Configure communication and navigation equipment.

• Maintain assigned headings, altitudes, and airspeeds.

• Intercept and track assigned courses.

• Recognize and resolve clearance discrepancies.

• Manage workload while receiving amended instructions.

Consider the following scenarios:

Scenario 1: Unable to Comply

ATC assigns an altitude that exceeds the aircraft’s current climb capability. How should you respond?

Scenario 2: Amended Clearance

While navigating to an assigned waypoint, ATC issues a new direct-to clearance. What steps should you take before changing course?

Scenario 3: Lost Communications

You experience a complete radio failure in IMC while receiving radar vectors. How would you determine the appropriate route and altitude?

Scenario 4: Clearance Misunderstanding

You receive an altitude assignment but are uncertain whether ATC instructed you to climb to 6,000 or 7,000 feet. What should you do?

These scenarios reinforce the importance of maintaining aircraft control, communicating effectively, and applying sound aeronautical decision-making.

Final Takeaway

Compliance with ATC clearances requires more than accurately repeating instructions. Instrument pilots must understand the authorization they have received, recognize when a clearance cannot be safely accepted, and maintain situational awareness while responding to changing instructions.

Developing consistent communication habits, maintaining proficiency with navigation equipment, and understanding pilot-in-command responsibilities are essential to safe IFR operations.

Effective IFR communication begins with understanding the clearance, verifying the instructions, and executing them accurately.

FAA References

• Instrument Rating – Airplane Airman Certification Standards 

• Aeronautical Information Manual — ATC Clearances and Aircraft Separation 

• Instrument Flying Handbook 

• 14 CFR §§ 91.3, 91.123, and 91.185.

This study guide is intended to supplement FAA publications and aircraft-specific procedures. Always follow current regulations, applicable FAA guidance, and instructions from Air Traffic Control.