To file an IFR flight plan, you build the plan (route, altitude, fuel, alternate, and equipment codes on FAA Form 7233-4), send it to Flight Service through an app like ForeFlight or Garmin Pilot, the 1800wxbrief.com website, or by phone at 1-800-WX-BRIEF at least 30 minutes before your proposed departure time, then contact Clearance Delivery or Ground before takeoff to copy the ATC clearance the plan generates. Federal regulations require both a filed plan and a clearance before you can operate IFR in controlled airspace, and the clearance you fly is the one ATC issues, not necessarily the one you filed.
When You Have to File
Under 14 CFR 91.173, you cannot operate in controlled airspace under IFR unless you have filed an IFR flight plan and received an ATC clearance.1eCFR. 14 CFR 91.173 – ATC Clearance and Flight Plan Required Two situations trigger the requirement most often. The first is weather below VFR minimums. In most controlled airspace (Class C, D, and E below 10,000 feet), VFR flight requires at least 3 statute miles of visibility and cloud clearances of 500 feet below, 1,000 feet above, and 2,000 feet horizontal. Surface-designated airspace around airports also requires at least a 1,000-foot ceiling.2eCFR. 14 CFR 91.155 – Basic VFR Weather Minimums When conditions fall below any of those numbers, you need to be IFR.
The second is altitude. Class A airspace, from 18,000 feet MSL up to Flight Level 600, is IFR-only regardless of weather.3Federal Aviation Administration. Designation of Airspace Classes You can also file IFR on a clear day at any altitude for the added safety of ATC separation, and the same rules apply once you do.
What Goes on the Form
An IFR flight plan is filed on FAA Form 7233-4, the ICAO-format international flight plan. Under 14 CFR 91.169, which incorporates the information requirements from 91.153, the plan must include the aircraft identification and type, the pilot-in-command’s name and address, the departure point and proposed time, the route of flight, cruising altitude and true airspeed, destination, estimated time en route, fuel on board in hours, the number of persons aboard, and an alternate airport when one is required.4eCFR. 14 CFR 91.169 – IFR Flight Plan Information Required
Equipment and Navigation Codes
The ICAO form includes fields for the aircraft’s navigation and communication equipment. Item 10a captures basic capabilities such as VOR, DME, and GPS through single-letter codes. Item 18 holds the Performance-Based Navigation (PBN) field, where you declare which RNAV and RNP specifications you can meet. If you plan to fly GPS-based Q-routes, T-routes, or RNAV SIDs and STARs, you file the letter “R” in Item 10a and the appropriate PBN code in Item 18. For example, “C2” indicates RNAV 2 using GNSS on a domestic Q-route, and “D2” indicates RNAV 1 GNSS on an RNAV SID or STAR.5Federal Aviation Administration. Appendix 4 – FAA Form 7233-4 International Flight Plan ATC uses these codes to decide which routes and approaches you’re equipped to fly. Wrong code, wrong routing.
Fuel
IFR fuel planning follows 14 CFR 91.167. You must carry enough fuel to fly to your destination, then from the destination to your alternate if one is required, and then fly for an additional 45 minutes at normal cruising speed. For helicopters, the final reserve is 30 minutes.6eCFR. 14 CFR 91.167 – Fuel Requirements for Flight in IFR Conditions Normal cruising speed means routine cruise, not a fuel-saving crawl. These are legal minimums. Weather, holds, and reroutes routinely eat into them.
The 1-2-3 Rule for Alternates
You can skip filing an alternate only if your destination has a published instrument approach and the forecast shows at least a 2,000-foot ceiling and 3 statute miles of visibility from one hour before through one hour after your ETA.4eCFR. 14 CFR 91.169 – IFR Flight Plan Information Required Pilots call this the 1-2-3 rule. Miss any of the three thresholds and an alternate must be filed.
The alternate must also meet weather minimums at your estimated arrival there. Standard alternate minimums are a 600-foot ceiling and 2 statute miles visibility for a precision approach such as an ILS, and an 800-foot ceiling and 2 statute miles visibility for a nonprecision approach.4eCFR. 14 CFR 91.169 – IFR Flight Plan Information Required Some airports publish higher nonstandard alternate minimums, so check the approach plates before assuming the defaults apply.
Picking a Route ATC Will Accept
You can file any combination of airways, fixes, and direct segments, but ATC is much more likely to clear you as filed if your route follows established traffic flow. The FAA publishes preferred IFR routes in the Chart Supplement to reduce reroutes and traffic management delays.7Federal Aviation Administration. Facility Operation and Administration – Preferred IFR Routes Program If a preferred route exists between your city pair, file it.
Standard Instrument Departures (SIDs) and Standard Terminal Arrival Routes (STARs) are published procedures that bridge the terminal environment and the en route airway structure. SIDs give you a charted climb path out of a busy airport; STARs organize the descent sequence into one. Both cut controller workload and frequency congestion.8Federal Aviation Administration. Aeronautical Information Manual – Departure Procedures When you include a SID or STAR in your plan, it becomes part of your filed route. If you’d rather not fly a STAR, put “NO STAR” in the remarks section.9Federal Aviation Administration. Aeronautical Information Manual – Section 4 Arrival Procedures
For short IFR trips between metropolitan areas, generally two hours or less, the Tower En Route Control (TEC) program keeps the whole flight inside approach control airspace using a network of predetermined low-altitude routes. TEC is primarily designed for non-turbojet aircraft at or below 10,000 feet. You file it through normal channels and add “TEC” in the remarks. Available TEC routes are published in the Chart Supplement alongside preferred routes.
How and Where to Submit the Plan
You can file through an Electronic Flight Bag app such as ForeFlight or Garmin Pilot, through the Leidos Flight Service website at 1800wxbrief.com, or by calling Flight Service at 1-800-WX-BRIEF (800-992-7433) and filing with a specialist.10Leidos Flight Service. 1800WXBrief The FAA recommends filing at least 30 minutes before your proposed departure time so the system can process the plan and have a clearance ready when you call for it.11Federal Aviation Administration. ENR 1.10 – Flight Planning The 30 minutes is a recommendation, not a regulatory requirement, but skipping it usually means waiting on the ramp.
A filed plan does not sit in the system indefinitely. Most Air Route Traffic Control Centers automatically purge a flight plan that hasn’t been activated within about two hours of the proposed departure time.11Federal Aviation Administration. ENR 1.10 – Flight Planning Running late? Refile or call to extend the proposed time before the plan disappears.
Copying the Clearance
Once the plan is in the system, contact Clearance Delivery at a towered airport, or Ground Control where there’s no separate Clearance frequency, to pick up your clearance. Most pilots copy it using the mnemonic CRAFT: Clearance limit (usually the destination), Route, Altitude (initial assigned), Frequency (departure control), and Transponder code. Read back the clearance exactly as given so the controller can confirm you copied it correctly. If any element doesn’t match what you filed, question it now, not after takeoff.
Don’t be surprised when the cleared route differs from what you filed. ATC amends routes for traffic flow, weather, and spacing. You might file direct and get three airways and two waypoints back. That’s the clearance you fly.
Non-Towered Airports and Void Times
At airports without an operating control tower, you typically receive the clearance by radio or phone from a remote ATC facility. It will include a void time: a specific clock time by which you must be airborne, after which the clearance expires. If you can’t make the void time, notify ATC as soon as possible of your intentions, and in any case no more than 30 minutes after the void time.8Federal Aviation Administration. Aeronautical Information Manual – Departure Procedures
Miss that 30-minute window and you’re considered overdue; search and rescue procedures begin, and all other IFR traffic into or out of that airport is held until ATC hears from you or 30 minutes elapse.8Federal Aviation Administration. Aeronautical Information Manual – Departure Procedures A missed void time does not cancel the plan or the clearance, but it withdraws your authority to depart IFR until ATC issues a new release.
ATC may also issue a “hold for release” instruction, which means you have a clearance but cannot depart until ATC gives you a specific release time. Hold-for-release applies only to IFR departure. You’re free to depart VFR if you cancel the IFR plan first, though picking up a clearance airborne in a busy area is not guaranteed.
Closing the Plan After Landing
At a towered airport, the plan closes automatically when the tower observes your landing. Nothing extra is required.
At a non-towered airport, closing is on you. Cancel with the approach controller while still on frequency during the approach, or call Flight Service by phone after landing. This is the step pilots forget after a long flight in hard IMC, and forgetting has consequences. When an IFR aircraft becomes overdue, the FAA initiates a communications search using INREQ (information request) and ALNOT (alert notice) procedures to locate it; ARTCCs distribute the alert notices, and the process escalates into search and rescue coordination with local authorities.12Federal Aviation Administration. FAA Order JO 7110.10 – Overdue Aircraft Make the cancellation call part of your post-landing flow, right after the avionics come off.