Overview

IFR flight planning is a structured process that ensures the flight is legal, safe, and resilient to changing weather and system conditions. Good IFR planning reduces unexpected diversions and workload by anticipating weather limitations, equipment needs, and suitable alternates.

Preflight checklist (practical)

• Weather analysis: Review METARs, TAFs, AIRMETs/SIGMETs, ceilings, visibility, icing and turbulence forecasts, and trends around departure, en route, and destination.
• Alternate planning: Choose alternates that meet regulatory and operator minima; verify published approaches, NOTAMs, and availability of navigation aids.
• Fuel & payload: Calculate fuel for planned route, reserve requirements, and fuel to reach alternates given likely contingencies and expected increased fuel burn in IMC or during holding/diversions.
• Equipment & authorization: Verify required avionics (comms, nav, DME, GPS/RNAV, transponder/ADS-B), MEL restrictions, and any operational approvals (e.g., RNAV authorization, LPV capability).
• Aircraft performance: Compute takeoff/landing distances for expected runway conditions, consider temperature/pressure/weight effects, and plan alternate airports if performance limits are marginal.
• Clearances & communications: Plan route and frequencies, file IFR flight plan, brief expected departure/arrival procedures, and review clearance delivery procedures.
• Contingency planning: Identify likely diversion points, lower minimums for missed approach planning, and emergency procedures for system failures (e.g., loss of GPS, partial panel).

Operational tips

• Build extra time margins for expected delays and alternate routing when severe weather or complex airspace is forecast.
• Where navigation is predicated on a single navaid (e.g., a VOR), verify serviceability and recent operational checks; avoid single-navaid reliance when possible for critical segments.
• Coordinate with dispatch or other pilots/operators to share weather and NOTAM insights when planning in marginal conditions.

Alternate Airport Requirements

Guidance for selecting alternates when filing IFR: ensure the alternate meets weather minimums, runway and approach availability, NOTAMs, airport operating hours, and any MEL/equipment considerations. Consider fuel to fly to the alternate, expected approach minima, and required pilot/aircraft qualifications.

• Weather minima: Confirm forecasted ceilings and visibility meet alternate minimums for the planned approach (or meet specified alternate criteria in applicable regulations).
• Approach availability: Ensure a suitable instrument approach is available at the alternate (e.g., circling, RNP, ILS, or LNAV minima as appropriate for the aircraft).
• Runway and facilities: Check runway length, lighting, and airport hours of operation.
• Fuel planning: Include fuel to reach the alternate and reserve fuel per regulations/operator policy.

VOR Alternate Requirements

When designating an airport whose published alternate approach is a VOR procedure, verify the following before filing or relying on that airport as an alternate:

• Published VOR approach: Confirm a current, published VOR (or VOR/DME) instrument approach procedure exists for the alternate and note whether straight-in or circling minima apply.
• Forecast weather: Verify the weather forecast for the alternate at the estimated time of arrival (ETA) ±1 hour meets the published minima for that VOR approach. Common planning minima used by operators include:
  • Straight-in non-precision approach: ceiling ≥ 800 ft AGL and visibility ≥ 2 statute miles.
  • Circling-only approach: expect higher minima (for example, ceiling ≥ 1,000 ft AGL and visibility ≥ 3 statute miles) — use the published circling minima or the operator's higher minima.
  • No instrument approach at alternate: typically requires ceiling and visibility sufficient for VFR descent and landing; many operators require an alternate with a published instrument approach.
  Always follow applicable regulations and your operator's or company alternate minimums — these example values are commonly used planning baselines, not legal substitutes for operator or regulatory minima.
• NOTAMs / NAVAID status: Check NOTAMs for the alternate and for the VOR ground facility (unserviceability, unusable segments, test outages). If the VOR is unserviceable or NOTAMed, the approach may not be available.
• Aircraft equipment & crew: Ensure the aircraft has serviceable VOR receivers and any required DME or GPS authorization, and that the crew is trained and current for the approach type (especially for circling or nonprecision procedures).
• Runway/lighting and airport hours: Confirm runway length, lighting, and the airport's hours support a safe landing given the approach type and expected conditions.
• VOR serviceability check: Confirm recent VOR operational check(s) as required by equipment/operations (e.g., § 91.171).
• Planning margin: Apply operator-prescribed buffers to published minima (for example many operators add a margin such as +400 ft / +1 SM) and ensure fuel allows diversion under those margins.

IFR Required Equipment

For IFR operations, the aircraft must have the instruments and equipment required by regulation, the aircraft's Type Certificate/AFM/POH, and any operator procedures or MEL. A common mnemonic used to remember the minimum flight instruments for IFR is GRABCARD:

• G — Generator/alternator and electrical source: Adequate electrical power for required equipment.
• R — Radios: Two-way radio communications and navigation radios appropriate for the route and approaches planned (VHF COM/NAV; additional avionics as required).
• A — Altimeter (sensitive): Adjustable for barometric pressure.
• B — Ball (inclinometer): Slip/skid indicator for coordinated flight.
• C — Clock: Installed or pilot-accessible clock with seconds for timing.
• A — Attitude indicator: Gyroscopic attitude reference (required for IMC).
• R — Rate of turn indicator: Gyroscopic turn information (or turn coordinator).
• D — Directional gyro / heading indicator: Reliable heading reference.

Additional required or commonly necessary equipment for IFR:

• Pitot-static system and pitot heat: Required for accurate airspeed and altitude information in IMC; pitot heat is essential in icing conditions.
• Transponder & ADS-B: Mode C/S transponder and ADS‑B Out where required by airspace; verify equipment meets current airspace mandates.
• Approach-specific avionics: DME, GPS/RNAV and associated approvals when required for RNAV/VNAV or GPS-based approaches; ILS receivers where ILS approaches are planned.
• Approach-specific avionics: Ensure required avionics and approvals are installed, serviceable, and current for the planned approaches. Be specific about equipment and flight levels when VOR navigation is required:
  • DME or RNAV (GPS): If VOR navigation is required for the route, note that operations at and above FL240 require approved DME or a suitable RNAV system per § 91.205(e). Ensure DME is serviceable or that the RNAV (GPS) system and databases are current.
  • GPS/RAIM/WAAS: When using GPS for RNAV or LPV approaches, verify RAIM availability (or WAAS integrity) for the planned route and ETA; ensure navigation database currency and any required authorization for the airspace/procedure.
  • LPV / LNAV-VNAV / VNAV: Confirm the aircraft has the specific vertical guidance capability required by the approach (baro-VNAV, WAAS/LPV capability, or approved RNAV system) and the crew/aircraft are authorized for such minima.
  • ILS: If planning ILS approaches, ensure localizer and glideslope receivers are serviceable and the aircraft is equipped and certified for the required approach category and minima.
  • Backup means: Plan for loss of GPS or DME (e.g., predicted RAIM outages) by identifying alternate navigation means or alternate airports with suitable approaches.
• Lighting: Position lights, anti-collision lights, and landing lights as required by operations and night flight rules.
• Charts & databases: Current approach plates, enroute charts, and navigation database updates where the equipment depends on them.
• MEL / Dispatch procedures: Do not dispatch IFR with required equipment inoperative unless authorized by MEL or specific operator procedures.
• Maintenance & checks: Ensure required inspections are current and any required operational checks (e.g., VOR checks under § 91.171) are completed.

Regulatory reference: 14 C.F.R. § 91.205 (minimum instruments and equipment). The regulation specifies the following minimum instruments and equipment for powered civil aircraft with standard U.S. airworthiness certificates.

Minimum items (selected verbatim from 14 C.F.R. § 91.205)

Visual-flight rules (day) — paragraph (b):

• Airspeed indicator.
• Altimeter.
• Magnetic direction indicator.
• Tachometer for each engine.
• Oil pressure gauge for each engine using a pressure system.
• Temperature gauge for each liquid-cooled engine.
• Oil temperature gauge for each air-cooled engine.
• Manifold pressure gauge for each altitude engine.
• Fuel gauge indicating the quantity of fuel in each tank.
• Landing gear position indicator, if the aircraft has a retractable landing gear.
• An approved aviation red or aviation white anticollision light system (as applicable by manufacture date and certification).
• For operation over water beyond power-off gliding distance from shore, approved flotation gear and at least one pyrotechnic signaling device (unless operating under part 121).
• An approved safety belt with approved metal-to-metal latching device for each occupant 2 years of age or older; shoulder harness requirements as applicable by manufacture date.
• An emergency locator transmitter (if required by § 91.207).

Visual-flight rules (night) — paragraph (c) additions:

• All instruments and equipment specified in paragraph (b).
• Approved position lights.
• An approved aviation anticollision light system.
• If the aircraft is operated for hire, one electric landing light.
• An adequate source of electrical energy for all installed electrical and radio equipment.
• One spare set of fuses, or three spare fuses of each kind required, accessible to the pilot in flight.

Instrument flight rules (IFR) — paragraph (d) additions:

• Instruments and equipment specified in paragraph (b) and, for night flight, paragraph (c).
• Two-way radio communication and navigation equipment suitable for the route to be flown.
• Gyroscopic rate-of-turn indicator (with limited exceptions for certain aircraft).
• Slip-skid indicator.
• Sensitive altimeter adjustable for barometric pressure.
• A clock displaying hours, minutes, and seconds with a sweep-second pointer or digital presentation.
• Generator or alternator of adequate capacity.
• Gyroscopic pitch and bank indicator (artificial horizon).
• Gyroscopic direction indicator (directional gyro or equivalent).

For operations at and above FL240 where VOR navigation equipment is required, § 91.205(e) requires approved DME or a suitable RNAV system.

Oxygen Requirements

Summarized requirements for supplemental oxygen (14 C.F.R. § 91.211):

• Cabin pressure altitudes 12,500–14,000 ft MSL: Flight crew must be provided with and use supplemental oxygen for any part of the flight exceeding 30 minutes at those altitudes.
• Cabin pressure altitudes above 14,000 ft MSL: Flight crew must be provided with and use supplemental oxygen during the entire time at those altitudes.
• Cabin pressure altitudes above 15,000 ft MSL: Each occupant must be provided with supplemental oxygen.
• Pressurized cabins — FL250 and above: An additional 10-minute supply of supplemental oxygen must be available for each occupant for use if a descent is required following loss of cabin pressurization; at and above FL350, one pilot at the controls must wear and use an oxygen mask that is secured and sealed, with additional requirements when only one pilot is at the controls.
• Reference: Full regulatory text: 14 C.F.R. § 91.211.

Note: Operators may have more restrictive policies; always follow operator manuals and airworthiness limitations.