IFR operating rules and publications

Know which source supplies which authority

The regulations establish legal operating requirements. The approved aircraft manual and supplements establish the installation's operating limitations. The Aeronautical Information Manual (AIM) explains procedures, services and recommended practices; an advisory description is not automatically a new regulation. Charts and NOTAMs supply the current procedure and facility information needed to apply those requirements.

Use the current versions together. A handbook illustrates a concept but may retain an older product name or procedure. A clearance authorizes a particular operation within the ATC system; it does not waive an aircraft limitation, required equipment or a regulation unless the applicable rule actually permits that authorization. If uncertain, identify the controlling source and resolve the conflict before accepting the operation.

AIM 5-5-1: roles, regulatory responsibilities and supplemental guidance · §91.9: approved operating limitations · §91.123: clearance/instruction compliance

File a proposal; receive the authority to fly it

Section 91.173 requires a filed IFR flight plan and an appropriate ATC clearance before operating under IFR in controlled airspace. Filing supplies information to the system; it is not permission to depart or enter cloud. The issued route may differ from the filed route. Loading the filed route into a navigator does not change that distinction.

The current ICAO-format IFR filing identifies the aircraft, flight rules/type, aircraft type and wake category, communications/navigation/surveillance capabilities, departure airport and UTC time, cruise speed/level and route, destination and estimated elapsed time, alternate when required, and applicable other/supplementary information such as fuel endurance, people aboard and contact/survival data. File capabilities the aircraft and pilot actually qualify to use; a checked equipment box cannot approve an installation. Lesson 17 applies these fields to a complete ground planning exercise.

Read a clearance as instructions with a clearance limit, route, altitude and any departure restrictions, plus the assigned communications and surveillance information. Compare it with terrain, aircraft performance and approved navigation capability. Read back the relevant instructions and resolve anything unclear immediately under §91.123. “As filed” adopts the filed route only when actually issued as part of the clearance; it does not make a previously filed proposal operative by itself.

When departing a nontowered airport, obtain a usable clearance and departure release using the published contact method. Hold for release means do not depart using that IFR clearance until ATC releases the flight. A release time establishes the earliest departure time. A clearance void time requires being airborne before that time. If it expires, do not depart IFR on the expired release authority; contact ATC as instructed for intentions and a new release.

Current AIM 5-2-7 clarifies that expiration of the void time withdraws authority to depart IFR; it does not itself cancel the entire departure clearance or flight plan. Notify ATC as soon as possible if not off in time, within the assigned notification limit. Do not confuse that notification interval with extra time to take off.

§91.173: IFR flight plan and clearance in controlled airspace · §91.123(a): compliance and immediate clarification · AIM 5-1-6: IFR filing and capability information · AIM 5-2-7: departure releases, hold for release and void times

Use the altitude rule for the actual airspace

In controlled airspace, §91.179 requires the altitude or flight level assigned by ATC for IFR level cruising flight, unless otherwise authorized. Do not leave an assigned 6,000 feet for 5,000 simply because the new course is eastbound. Request an amendment when the assigned altitude is unsuitable.

For IFR level cruising flight in uncontrolled airspace below 18,000 feet MSL, the rule uses magnetic course: 0°–179° takes odd thousands, and 180°–359° even thousands, with the specified exceptions for holding or turning. These are whole-thousand IFR altitudes, not VFR's added 500 feet. Use course over the ground, not the wind-corrected heading.

Minimum IFR altitude requirements are separate from the direction-of-flight cruising rule. Section 91.177 uses the applicable published minimums; where none are prescribed, it requires 2,000 feet above the highest obstacle within 4 NM of the course in designated mountainous areas, or 1,000 feet in other areas, except as provided for takeoff/landing or FAA authorization. Published crossing and climb requirements also matter.

When both MEA and MOCA are published, operation down to the MOCA requires available applicable navigation signals; for VOR navigation the rule limits this to within 22 NM of the VOR. A chart altitude cannot be treated as a blanket guarantee of every communication, navigation or radar service. Learn the chart legend and procedure context before relying on it.

VFR-on-top is an IFR clearance with additional responsibilities: appropriate VFR cruising altitude and VFR weather/cloud clearance, plus the applicable IFR minimums, routing, reporting and communication requirements. It does not cancel the IFR flight plan. A sunny view above cloud is not itself a VFR-on-top authorization.

§91.179(a)–(b): controlled/uncontrolled IFR cruising altitudes · §91.177: minimum altitude, MOCA/VOR limits and climb/crossing requirements · AIM 5-5-13: VFR-on-top responsibilities

Radar contact changes some reports, not all duties

Unless otherwise authorized, §91.183 requires a continuous watch on the appropriate frequency in controlled-airspace IFR. Report designated or specifically requested reporting points, unforecast weather and information relating to safety. Under radar control, the ordinary position-point reports are reduced to those ATC specifically requests. “Radar contact” does not remove the weather or safety-report obligations.

AIM 5-3-2 explains compulsory and on-request reporting-point symbols and position-report content: identification, position, time, altitude, next-point estimate and the following point, with relevant remarks. Resume the applicable nonradar reports when radar contact/service is lost or terminated. Maintain an accurate estimate using the actual winds and groundspeed.

AIM 5-3-3 recommends additional reports without a specific request, including vacating an assigned altitude, a missed approach, reaching/leaving a holding fix, inability to climb/descend at least 500 feet per minute, and applicable equipment impairment. It also describes the nonradar final-approach and corrected-estimate reports. Treat these procedure recommendations carefully while distinguishing them from the underlying regulatory reports.

Tell ATC when a clearance cannot be safely met, and request what is needed: a workable altitude, route, delay or approach. Include the actual limitation and the assistance requested. Under §91.187, relevant navigation or communication malfunctions in controlled-airspace IFR must be reported as soon as practical. Never accept an unworkable instruction merely because the controller offered it.

§91.183: listening watch, reporting points, weather and safety · §91.187: IFR malfunction reports · AIM 5-3-2 and 5-3-3: position and additional reports · AIM 5-5-2 and 5-5-9: clearance and aircraft-performance responsibilities

Use ATC help while retaining pilot responsibility

ATC provides applicable traffic separation, clearances, vectors and information within the service and airspace involved. Pilots retain responsibility for aircraft control, fuel, equipment capability and weather decisions. Terrain responsibility depends on the procedure and clearance; an assumed future vector is not a terrain plan for an unpublished departure.

Radar surveillance and radio coverage are limited by terrain, altitude, equipment and workload. Traffic advisories can omit aircraft that are not detected or cannot be reported while the controller handles higher priorities. Safety alerts depend on the controller recognizing the developing hazard. When weather permits, see and avoid remains a pilot responsibility regardless of the flight plan.

ATC weather displays help with broad precipitation awareness but do not guarantee a safe gap or show every hazard. Ask for assistance early, state the deviation needed and maintain a safe alternative. A controller's ability to offer a route through weather does not establish that this airplane can safely use it.

These responsibilities apply through departure, en route and arrival. Review the clearance at each transition, compare it with the current chart and aircraft state, and speak up before a restriction becomes impossible. A frequency change, approach clearance or advisory-frequency instruction does not by itself mean IFR has been canceled.

AIM 5-5-1, 5-5-2, 5-5-7, 5-5-8 and 5-5-10: pilot/controller responsibilities and service limits · AIM 5-1-16: navigation infrastructure and unpublished RNAV departure terrain responsibility · ACS V.B.K2: responsibilities, communication and ATC services

Assemble a current route-to-runway information set

Use current IFR en route charts for routes, fixes, navigation facilities, altitude restrictions and airspace. Use the Terminal Procedures Publication (TPP) for applicable departure, arrival and approach procedures, takeoff/obstacle information, alternate minima and related notes. Use the Chart Supplement for airport data, runways, lighting, communications, services and facility remarks. Preferred routes and ATC planning information can guide a proposal without guaranteeing that route will be cleared.

Special use airspace (SUA) must be assessed by type, lateral/vertical limits, scheduled activity and controlling agency. Prohibited areas exclude the operation; restricted areas require the applicable authorization and can contain invisible military hazards. On a joint-use restricted-area IFR route, ATC can clear traffic through when it is inactive and released; otherwise the route must avoid it unless the appropriate permission applies. Active military operations areas (MOAs) may be available to nonparticipating IFR traffic when ATC can provide separation, or may require a reroute. A MOA is not treated as a prohibited area, and a filed direct line is not SUA authorization.

Use chart margins, current SUA status, appropriate NOTAMs and the using/controlling agency to determine the effect on the flight. Temporary restricted areas and temporary MOAs may not appear on the chart. Evaluate the reroute's terrain, weather, time and fuel before departure instead of assuming that scheduled inactivity guarantees passage.

Review the appropriate NOTAMs for departure, destination, alternates, route facilities and airspace, including GPS interference/testing, runway/taxiway closures, approach changes, navigation outages and temporary restrictions. Check effective times in UTC and the affected procedure, runway or facility. A valid chart can be modified by a current NOTAM; a current airport forecast does not show a runway closure.

A paper chart, electronic chart and navigator database have separate validity checks. Verify the edition/effective period and that the loaded procedure matches the current published one. A database screen saying a fix exists does not prove the whole approach is current or authorized. Obtain the applicable current information and follow the installed system's database restrictions before using it.

Example: an EFB shows a familiar approach, but a procedure NOTAM makes it unavailable and a runway NOTAM closes the other usable runway during the ETA window. Treat the airport's operational usability as changed even when its weather is excellent. Outdated information can become a navigation, terrain or landing hazard.

AIM 5-1-1, 5-1-3 and 5-1-6: preflight information, NOTAMs and IFR plans · FAA Aeronautical Information Services: digital charts, Chart Supplements and TPP products · AIM 3-4-1 through 3-4-9: SUA types, IFR coordination and status · ACS I.C.K1b/e/f/g/h, K4/K5: current publications and filing · ACS II.C.R2: outdated publications/databases

End IFR intentionally and ensure the plan is closed

Under §91.169(d), after an activated flight plan is canceled or completed, the PIC must notify an FAA Flight Service Station or ATC facility. Current AIM 5-1-15 explains that an IFR flight plan to an airport with a functioning control tower is automatically closed upon landing. At an airport without a functioning tower, the pilot must initiate cancellation; plan the radio, published telephone or other available communication method before arrival.

A pilot may cancel IFR in VFR conditions outside Class A. Before canceling airborne, confirm that the remaining operation can safely and legally continue VFR, including terrain, cloud clearance, airspace and visibility. Seeing the runway through a gap does not necessarily establish those conditions. It can be appropriate to retain IFR through landing and cancel afterward.

Canceling ends the IFR separation/service arrangement described in the AIM. If VFR radar advisories are desired, request them and follow applicable airspace instructions; do not assume they continue automatically. A change to the airport advisory frequency is not cancellation. Prompt closure after a nontowered landing releases protected airspace and prevents unnecessary overdue/search actions.

§91.169(d): cancellation/completion notification · §91.123(a): cancellation in VFR conditions except Class A · AIM 5-1-15: cancellation, functioning-tower closure and pilot initiation elsewhere

FLIGHT SCENARIO

What would change your plan?