What is required to file an IFR flight plan?

To file an IFR flight plan, a pilot must provide information including the aircraft identification, type and equipment suffix, departure and destination airports, estimated time en route, alternate airport (when required), fuel on board, and the proposed route of flight. The flight plan is typically filed with a Flight Service Station or through an approved online or electronic filing system before departure. Per 14 CFR Part 91, the IFR flight plan must be filed and an ATC clearance received before operating in controlled airspace under IFR.

What's the difference between a VFR flight plan and an IFR flight plan?

A VFR flight plan is voluntary and serves primarily as a search-and-rescue tool — it does not provide ATC separation services and does not require a clearance before flight. An IFR flight plan, by contrast, is a regulatory requirement when operating under Instrument Flight Rules, and it activates ATC separation services that keep the aircraft clear of terrain, obstacles, and other IFR traffic. Filing an IFR flight plan also obligates the pilot to meet specific equipment, currency, and weather minimums established by 14 CFR Part 91 and the Aeronautical Information Manual.

Why do you need an alternate airport on an IFR flight plan?

An alternate airport is required on an IFR flight plan when the weather forecast at the destination airport does not meet the '1-2-3 rule' outlined in 14 CFR 91.169 — specifically, if the forecast within one hour before and after the estimated time of arrival shows a ceiling of less than 2,000 feet or visibility less than 3 statute miles. The alternate ensures a pilot has a viable backup destination if the primary airport becomes unusable due to weather or other factors. The alternate airport itself must also meet specific weather minimums at the estimated time of arrival, and those minimums vary depending on whether the airport has an instrument approach and what type of approach is available.

Instrument Flight Rules Flight Plan Requirements

Every instrument-rated pilot knows the feeling: weather is moving in, ceilings are dropping, and the only legal and safe option is to operate under Instrument Flight Rules. But before you push the throttle forward and climb into the clouds, the regulatory framework demands that a specific set of conditions, equipment checks, and paperwork be in place. Understanding IFR flight plan requirements is not just about passing the FAA knowledge test — it is about operating confidently and legally every time you enter the IFR system.

This article walks through every major element the FAA requires for IFR flight plan filing, from the regulatory foundation in 14 CFR Part 91 and the AIM to the practical cockpit-level details that keep you legal and safe.

The Regulatory Basis

The authority for IFR flight operations in the United States stems primarily from 14 CFR Part 91. Section 91.169 governs IFR flight plan requirements, while 91.167 through 91.187 collectively address fuel requirements, equipment, ATC clearances, and position reporting. The Aeronautical Information Manual (AIM) Chapter 5 provides the procedural guidance that complements those regulations.

Operating IFR in controlled airspace without an ATC clearance is not permitted. That clearance is issued in response to a filed flight plan, which means the flight plan itself is the first link in the legal chain that authorizes you to operate in IMC within the National Airspace System (NAS).

What Goes Into an IFR Flight Plan

An IFR flight plan is filed using FAA Form 7233-1 (the standard domestic flight plan form) or its electronic equivalent through outlets such as 1800wxbrief.com or avionics-integrated systems. The AIM Chapter 5-1 describes each field. Here is what must be included:

Aircraft identification: Your full N-number or ICAO designator exactly as it appears in the aircraft registration.
Type of flight plan: Marked as IFR (or a combination such as VFR/IFR for a composite plan).
Aircraft type and special equipment suffix: For example, C172/G indicates a Cessna 172 with a WAAS GPS receiver. The suffix tells ATC what navigation capability you have, which affects routing and approaches available to you.
True airspeed (TAS): Estimated cruise TAS in knots. This is used for ATC planning, not a binding limit.
Departure point: The ICAO identifier of the departure airport.
Proposed departure time: In UTC (Zulu). Your flight plan activates within two hours of this time; if you do not depart within that window, you must refile or amend.
Cruising altitude: The initial requested altitude. ATC will assign an actual altitude in the clearance, which may differ.
Route of flight: Airways, fixes, direct routing, or a combination. Use designated airways (Victor airways below 18,000 feet MSL; Jet routes at and above FL180) or published waypoints.
Destination airport: The ICAO identifier. IFR flight plans must have a specific destination — you cannot file IFR to an unspecified point.
Estimated time en route (ETE): Hours and minutes to destination. This triggers search and rescue if you are overdue by 30 minutes past ETE without closing the flight plan.
Remarks: Any pertinent notes — such as pilot certification level, special equipment, or PIREP information — go here.
Fuel on board: In hours and minutes. ATC uses this for SAR purposes if contact is lost.
Alternate airport: Required when specific weather conditions exist at the destination (see below).
Pilot information and aircraft color: Name, address, phone number, and aircraft color scheme — again, for SAR use.

The Alternate Airport Requirement

One of the most commonly tested areas on the instrument knowledge exam is the alternate airport requirement found in 14 CFR 91.169(b) and (c). The rule has two parts.

First, you must file an alternate airport unless the destination airport has a published instrument approach procedure AND the weather forecast for the destination, from one hour before to one hour after your estimated time of arrival (ETA), meets the following: ceiling at least 2,000 feet and visibility at least 3 statute miles. This is the classic 1-2-3 rule: one hour before to one hour after, 2,000-foot ceiling, 3 SM visibility. If those conditions are forecast, no alternate is required. If they are not met — or if the destination has no instrument approach — an alternate must be filed.

Second, if an alternate is required, the alternate airport itself must meet its own weather standards at your estimated time of arrival there:

If the alternate has a precision approach (such as an ILS): forecast ceiling at least 600 feet and visibility at least 2 SM.
If the alternate has only a non-precision approach: forecast ceiling at least 800 feet and visibility at least 2 SM.
If the alternate has no instrument approach: the ceiling and visibility must allow descent from the MEA and landing under basic VFR conditions.

Note carefully: these are filing standards, not operational minimums. When you actually fly the approach at the alternate, you must use the approach minimums published on that procedure.

IFR Equipment Requirements

Filing an IFR flight plan is meaningless if the aircraft is not equipped to operate IFR legally. Under 14 CFR 91.205(d), the required instruments and equipment for IFR flight in controlled airspace include, at minimum:

Gyroscopic rate-of-turn indicator (or a third attitude instrument system)
Slip-skid indicator
Sensitive altimeter adjustable for barometric pressure
Clock with hours, minutes, and seconds
Attitude indicator
Heading indicator
Radios suitable for the route and area to be flown
Generator or alternator of adequate capacity
DME or RNAV equipment at or above FL240 if VOR navigation is used

The common mnemonic for this list is discussed below. Additionally, transponder requirements under 91.215 (Mode C capability in most controlled airspace) apply. In RVSM airspace (FL290–FL410), additional equipment and authorization are required.

Memory Aid

The mnemonic GRABCARD covers the required instruments for IFR flight under 91.205(d):

G — Generator or alternator
R — Radios (navigation and communication suitable for the route)
A — Altimeter (sensitive, adjustable)
B — Ball (slip-skid indicator)
C — Clock (with sweep second hand or digital equivalent)
A — Attitude indicator
R — Rate-of-turn indicator
D — Directional gyro (heading indicator)

Run through GRABCARD during your preflight to confirm IFR legality before ever filing.

Fuel Requirements for IFR Flight

Under 14 CFR 91.167, no person may operate a civil aircraft in IFR conditions unless there is enough fuel to complete the flight to the first airport of intended landing, then fly from that airport to the alternate airport (if one is required), and then fly for an additional 45 minutes at normal cruising speed. This differs from the VFR fuel reserve (30 minutes day, 45 minutes night for airplanes) and is a commonly tested distinction. The 45-minute IFR reserve applies regardless of day or night.

Opening, Amending, and Closing the Flight Plan

A filed IFR flight plan does not open automatically. In controlled airspace, it is activated when ATC issues your clearance and you depart. In uncontrolled airspace, you may need to open the flight plan yourself by radio or phone. Critically, you are responsible for closing your IFR flight plan when you land at an airport without an operating control tower. If you land at a towered airport, the tower normally closes it for you. Failure to close results in search-and-rescue resources being activated 30 minutes after your ETE expires — a serious and resource-wasting event.

Common Test Traps

The 1-2-3 rule window: Many students misremember the alternate airport exemption. The correct forecast period is one hour before to one hour after ETA — not just at ETA. If any part of that three-hour window dips below 2,000 feet ceiling or 3 SM visibility, an alternate is required.
Filing minimums vs. approach minimums: The weather standards for selecting an alternate (600/2 for precision, 800/2 for non-precision) are planning standards only. The actual minimums you fly when you arrive are whatever is published on the approach plate — often lower.
IFR fuel reserve is always 45 minutes: Unlike VFR rules, the IFR 45-minute reserve does not change between day and night. Many students incorrectly apply the VFR 30-minute daytime rule to IFR operations.
No alternate needed ≠ no alternate exists: Being exempt from filing an alternate because forecast weather is good does not mean you should not think about one. It is a regulatory minimum, not a strategic ceiling — good ADM means always having a contingency.
Flight plan expiration: An IFR flight plan held by ATC will be purged if you do not depart within approximately two hours of your proposed departure time. Always amend your departure time if delays occur to avoid having no active flight plan when you call for your clearance.