ACS Task IR.VIII.A — Postflight Instrument and Equipment Check

What does ACS Task IR.VIII.A cover?

IR.VIII.A is the final task of the instrument rating checkride and it tests whether you treat the postflight as a deliberate, procedurally complete phase of flight — not an afterthought. The FAA Instrument Rating ACS (FAA-S-ACS-8C) organizes IR.VIII.A into Knowledge, Risk Management, and Skill elements. The core subject matter spans three regulatory areas: verifying instruments and avionics functioned correctly, properly deferring any inoperative equipment, and formally closing the IFR flight plan.

DPEs test this task primarily through oral questioning — they may describe a scenario in which an instrument behaved abnormally during the flight and ask you to walk through your postflight response. A candidate who says "I'd just write it up" without citing the applicable regulatory path will not satisfy the ACS standard.

How do you verify instruments worked correctly during the flight?

The postflight instrument check is a systematic review of every instrument required by 14 CFR 91.205(d) for IFR flight. The required IFR equipment list includes all VFR-day instruments plus:

Walk through each item on shutdown: did the attitude indicator erect properly and remain stable throughout? Did navigation receivers hold signal, sequence waypoints correctly, and display consistent data? Did the altimeter agree within limits? Any anomaly observed during flight — a flickering gyro, a nav receiver that lost GPS lock at an unexpected moment — is a squawk that must be addressed before the next flight.

What is a squawk and how do you record it?

A squawk is any discrepancy, malfunction, or anomaly noted in an aircraft system. After an IFR flight, any equipment anomaly — even intermittent — must be recorded in the aircraft maintenance logbook or discrepancy log so maintenance personnel can evaluate it. Failing to record a known squawk shifts liability to the PIC and may allow an unsafe condition to be discovered (or not discovered) by the next crew.

For aircraft operating under Part 91, the recordkeeping requirement is in 14 CFR 91.213 and Part 43. An equipment entry must describe the inoperative item with enough specificity for a mechanic to identify and evaluate it. "Nav radio intermittent" is insufficient; "COM1 lost audio on transmit during cruise at 8,500 ft, 2026-05-17, squawk logged" is the standard.

What are the two paths to defer inoperative equipment?

When an instrument or piece of equipment is found inoperative before or after flight, a pilot must use one of two regulatory paths before the aircraft can legally fly again — or determine the flight cannot legally proceed.

Path 1: Approved MEL with letter of authorization

Under 14 CFR 91.213(a), an aircraft may be operated with inoperative instruments or equipment if an approved Minimum Equipment List exists for that aircraft and the operator holds an FAA letter of authorization from the Flight Standards office. The MEL specifies exactly which items may be inoperative, under what conditions, and for how long. When deferring under the MEL, the aircraft records must include an entry describing the inoperative instrument or equipment. The aircraft must be operated within all MEL conditions and limitations.

Most small general aviation aircraft — Cessna 172, Piper Archer, Beechcraft Bonanza — do not have an approved MEL. If yours does not, you must use Path 2.

Path 2: The 91.213(d) four-condition deferral

Under 14 CFR 91.213(d), aircraft without an approved MEL may operate with inoperative equipment if all four of the following conditions are met:

1. 1
   The aircraft is an eligible type: rotorcraft, non-turbine-powered airplane, glider, lighter-than-air aircraft, powered parachute, or weight-shift-control aircraft (with or without a master MEL developed for the type).
2. 2
   The inoperative item is not: (a) part of the VFR-day type certification requirements, (b) listed as required on the aircraft's equipment list or Kinds of Operations Equipment List, (c) required by 14 CFR 91.205 for the specific operation, or (d) required to be operational by an airworthiness directive.
3. 3
   The inoperative item is either removed from the aircraft and the cockpit control placarded, or it is deactivated and placarded 'Inoperative.' If deactivation requires maintenance, it must be recorded in accordance with 14 CFR Part 43.
4. 4
   A certificated pilot or a person holding a certificate issued under 14 CFR Part 65 determines that the inoperative equipment does not constitute a hazard to the aircraft.

The critical constraint for IFR operations: condition 2(c) blocks deferral of any item required by 91.205(d). An attitude indicator, directional gyro, altimeter, or any other instrument on the IFR required list cannot be deferred under 91.213(d) for an IFR flight. The aircraft is grounded for IFR until the item is repaired — or an approved MEL specifically permits the deferral.

How do you close the IFR flight plan?

Closing the IFR flight plan is a positive PIC responsibility — it does not happen automatically when you land. Per AIM 5-1-15, your procedure depends on where you are when you land:

If you fail to cancel and ATC cannot confirm your landing, they will initiate overdue action — first alerting FSS and adjacent facilities, then potentially initiating search-and-rescue procedures. A missed cancellation is not a minor administrative failure; it diverts real SAR resources.

You may cancel IFR in flight if you are operating in VMC outside controlled airspace and no longer require IFR separation. Tell ATC "Cancel IFR" and confirm the cancellation is acknowledged before leaving the frequency.

What are the VOR logbook check requirements under 91.171?

The postflight period is also the correct time to verify your VOR check entry remains current before the next IFR departure. Under 14 CFR 91.171(a), no person may operate a civil aircraft under IFR using VOR equipment unless that equipment was checked within the preceding 30 days. The check method determines the tolerance:

Per 14 CFR 91.171(d), the person performing the check must enter the date, place (or the airway and the point used), bearing error, and their signature in the aircraft log or other record. No entry — no legal IFR flight using VOR.

Risk Management elements in IR.VIII.A

The ACS risk management elements for this task center on one core question: what is the consequence of leaving a discrepancy unaddressed?

Leaving an intermittent squawk unrecorded is the most common risk. An attitude indicator that fluttered briefly during cruise may be a worn gimbal bearing. The next crew may fly that aircraft into IMC with no warning. Recording the squawk is the PIC's last line of defense.

Misapplying 91.213(d) creates the second major risk. If a pilot concludes that an IFR-required instrument can be deferred under 91.213(d) without checking condition 2(c), they may depart IFR illegally. The 91.205(d) check is not optional — any item on that list is automatically disqualified from 91.213(d) deferral for IFR operations.

Forgetting to cancel the IFR flight plan is operationally simple but regulatory serious. Per AIM 5-1-15, the consequence is a potential SAR activation. The habit should be: close the plan before shutting down the radio.

Skill elements: the postflight inspection sequence

The ACS Skill element requires you to conduct the postflight check in a systematic, complete sequence. A defensible approach:

1. 1
   Shut down per POH checklist. Note any abnormal indications during shutdown (gyro spin-down anomalies, avionics warnings, circuit breaker trips).
2. 2
   Review the flight mentally: any instrument that behaved unexpectedly during the flight? Nav receiver anomalies, altimeter inconsistencies, attitude indicator lag?
3. 3
   Record all squawks in the aircraft logbook or discrepancy log with sufficient detail for maintenance evaluation.
4. 4
   For any inoperative item: determine if it is required by 91.205(d) for IFR — if yes, the aircraft cannot fly IFR until repaired. If not required by 91.205(d), apply the 91.213(d) four-condition test or MEL provisions.
5. 5
   Verify the IFR flight plan is closed: confirm ATC closed it on landing, or cancel by radio/phone before leaving the ramp.
6. 6
   Check the VOR logbook entry: confirm the check was within the preceding 30 days if the next flight will require VOR navigation under IFR.
7. 7
   Secure the aircraft per applicable procedures. Leave a note for the next crew if any squawk is deferred.

What the DPE Looks For

DPEs use IR.VIII.A to evaluate procedural completeness and regulatory fluency. Three qualities distinguish a strong candidate:

1. Regulatory precision on 91.213: Can you explain both the MEL path (91.213(a)) and the 91.213(d) deferral path, and correctly identify which instruments are excluded from 91.213(d) deferral for IFR operations? Most candidates know "you can defer it" without knowing the conditions.
2. IFR flight plan closure habits: Many candidates overlook this. DPEs look for candidates who explicitly name AIM 5-1-15 and describe the non-towered airport procedure — not just "I'll call ATC."
3. VOR check currency awareness: A candidate who can cite the 30-day window, the four check methods, the tolerances, and the required logbook entry demonstrates the kind of procedural completeness the ACS demands.

Common Errors in IR.VIII.A

• Treating the postflight as optional — failing to describe a systematic, instrument-by-instrument review and assuming 'nothing seemed wrong' is sufficient.
• Misidentifying the 91.213(d) conditions — most commonly stating that any inoperative item can be deferred if placarded, without knowing the 91.205(d) carve-out.
• Confusing the MEL path with 91.213(d) — these are two separate paths; MEL requires FAA approval and a letter of authorization, 91.213(d) does not.
• Assuming the IFR flight plan closes automatically at landing — it only closes automatically at a towered airport when ATC acknowledges your landing under an IFR clearance.
• Not knowing the VOR check tolerance difference between ground checks (±4°) and airborne/in-flight checks (±6°).
• Failing to describe what must be in the VOR check logbook entry — date, place, bearing error, and signature are all required by 91.171(d).
• Skipping the hazard determination step under 91.213(d)(4) — a certificated pilot or Part 65 certificate holder must affirmatively determine the item poses no hazard; this is not automatic.

Practice Questions

Frequently Asked Questions

Sources

• 14 CFR 91.213 — Inoperative Instruments and Equipment (Cornell LII)
• 14 CFR 91.205 — Powered Civil Aircraft with Standard Airworthiness Certificates (Cornell LII)
• 14 CFR 91.171 — VOR Equipment Check for IFR Operations (Cornell LII)
• AIM 5-1-15 — Canceling an IFR Flight Plan (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) and cross-referenced against Cornell LII for current regulatory text by MockDPE. Last updated: May 2026. If you spot an inaccuracy, email corrections@mockdpe.org.