Flight planning, step by step
A nav log is not paperwork. It is the document that tells you, in flight, whether what is happening matches what you expected — and that is the whole point of making one.
Last updated August 2026
1. Route
Start with the straight line, then bend it for good reasons: terrain, airspace, restricted areas, and a landable field within gliding reach where you can arrange it. A direct track that crosses fifteen miles of unbroken forest at 2,500 feet is shorter than the one that follows the valley, and worse.
For IFR, routes are usually expressed as fixes and airways —
KFFZ IFNUR PXR V105 DRK KSEZ. Each airway expands into the fixes along
it, and each has a minimum enroute altitude you must be able to make.
2. Cruise altitude
Three constraints, all of which must be satisfied:
- Terrain and obstacles — with a real margin, not a token one.
- Cruising altitude rules — above 3,000 feet AGL VFR, easterly headings (0–179° magnetic) take odd thousands plus 500, westerly (180–359°) even thousands plus 500. IFR uses odd and even thousands on the same split.
- Winds and performance — higher is usually more efficient, until the headwind or the climb fuel eats the gain.
Then check it against the weather: an altitude in cloud is not available to you VFR, and an altitude in icing conditions is not available to most light aircraft at all.
3. Winds aloft
Winds aloft forecasts are given in true direction, in knots, for standard levels. They are what turn a still-air estimate into a usable one.
For each leg you need the wind correction angle and the groundspeed. The arithmetic is a wind triangle; in practice you let software or a flight computer do it, but the sanity check is worth internalising: a headwind component costs you time and fuel roughly in proportion, and a crosswind component costs you heading, not much speed.
Do not average the winds across a long leg if the forecast changes materially along it. Break the leg at the point the forecast changes and treat the halves separately, or you will arrive with a fuel figure that was never right at any point in the flight.
4. Headings
The chain, in order:
- True course — measured off the chart.
- True heading — true course corrected for wind.
- Magnetic heading — true heading corrected for magnetic variation. West variation is added, east subtracted.
- Compass heading — magnetic heading corrected for the aircraft's own deviation card.
Variation is not a rounding error. It runs past 20° in parts of the western United States and considerably more in Alaska, which is enough to miss an airport entirely on a hundred-mile leg.
5. Time, fuel and reserves
Distance divided by groundspeed gives leg time; leg time times burn rate gives leg fuel. Then add, honestly:
- Taxi and run-up — small but real.
- Climb fuel — significantly higher burn than cruise, and it is a large fraction of a short flight.
- Reserve — VFR day requires 30 minutes at cruise, VFR night and IFR 45 minutes. Those are legal minimums, not planning targets.
- Alternate — if the destination forecast requires one, the fuel to get there and then hold your reserve on top.
Legal reserve is the number below which you have broken a rule, not the number at which you should start worrying. Pick a personal minimum — an hour is a common choice — and treat reaching it as a decision point rather than a milestone you pass.
6. Alternates
For IFR, the familiar rule of thumb is 1-2-3: an alternate is required unless, for one hour either side of your ETA, the forecast ceiling is at least 2,000 feet and visibility at least 3 statute miles. Then check the alternate itself has the approaches and the forecast minimums to be usable when you would actually arrive there.
For VFR there is no such rule, which makes it more important rather than less. Pick the field you would divert to on each segment before you depart, and know its frequencies and runway lengths.
7. Brief the weather last, and re-brief
Work through METARs and TAFs for departure, destination and alternate; the winds aloft you used; AIRMETs and SIGMETs along the route; TFRs; and NOTAMs for anything closed or out of service. Then check it again before you actually leave. A briefing from four hours ago is a historical document.
Doing it in Flight Kneeboard
Enter a route in the route field — plain identifiers, or fixes and airways, which expand automatically. Open Planner to set aircraft profile, cruise altitude, power setting and fuel on board, then Flight plan & briefing produces the nav log with winds-corrected times, climb, cruise and descent performance, a fuel plan broken down by taxi, enroute and reserve, and departure and destination airport information. It can be printed or saved as a PDF to take with you.
The numbers are only as good as the aircraft profile behind them. Set yours from your own POH figures and your own observed burn, not the book's optimistic one.