Building your nav log from scratch and why every box on that form matters before your solo cross-country

A navigation log is a prediction of what your airplane will do on a cross-country flight — your headings, times, fuel burn, and visual checkpoints — built before you leave the ground. Completing one accurately is a requirement for the solo cross-country and the private pilot checkride under the Airman Certification Standards. The process is methodical: plot your course, correct for wind, convert to a flyable heading, and calculate time and fuel for every leg.

What Is a Nav Log and Why Does It Matter?

A nav log is not busywork. It’s a structured prediction that you compare against reality in flight. You calculate how long each leg will take, how much fuel you’ll burn, what heading to fly, and what landmarks you’ll see. In the air, you compare actual performance to those predictions. When reality diverges from the plan, the nav log tells you something changed — and gives you the information to figure out what.

The entire process follows one loop: predict, compare, adjust.

How Do I Set Up My Route?

Start with your departure airport, destination, and at least one intermediate waypoint. For a solo cross-country under 14 CFR Part 61, you need at least 150 nautical miles total distance with one leg of at least 50 nautical miles straight-line.

Unfold your sectional chart on a large surface. Draw your course lines in pencil — straight lines from departure to first waypoint, waypoint to waypoint, and final waypoint to destination. Each leg needs a checkpoint at the beginning and end.

Choose checkpoints visible from 3,000 feet AGL or higher: towns, lakes, highway intersections, VORs. A water tower works. A specific house does not. If you can’t find it at altitude, it doesn’t belong on your nav log.

How Do I Find True Course?

Use your plotter aligned along each course line. Read the true course off the nearest line of longitude — the lines running north-south. Reading from a latitude line instead is one of the most common student errors and will throw your course off significantly.

Sanity-check every reading. If you’re flying west to east, your course should be somewhere near 090°. If you read 180°, something went wrong. Common sense catches plotter mistakes before they become in-flight problems.

How Do I Calculate Wind Correction and Groundspeed?

Pull the winds and temperatures aloft forecast from your weather briefing. Identify the wind direction and speed at or near your cruising altitude. If you’re cruising at 4,500 feet, you may interpolate between the surface wind and the 6,000-foot forecast, or use the 3,000- or 6,000-foot winds directly with your instructor’s guidance.

Set up your E6B flight computer (manual or electronic) with the wind direction and speed, your true course, and your true airspeed from the POH. The E6B solves for two values:

• Wind correction angle (WCA) — how many degrees to crab into the wind
• Groundspeed — your actual speed over the ground

For example, with a true course of 095°, true airspeed of 110 knots, and wind from 270° at 15 knots, the E6B might return a WCA of 8° left and a groundspeed of 102 knots.

What Is the Heading Chain From True Course to Compass Heading?

This is the sequence the examiner wants you to demonstrate and explain:

1. True course ± wind correction angle = true heading. (095° − 8° = 087°)
2. True heading ± magnetic variation = magnetic heading. Find the nearest isogonic line on your sectional. Remember: east is least, west is best. With 7° west variation: 087° + 7° = 094° magnetic heading.
3. Magnetic heading ± compass deviation = compass heading. Check your airplane’s compass deviation card. If deviation at 090° is +2°, your compass heading is 096°.

Each step is simple on its own. The examiner is testing whether you understand how the chain links together and can show the math.

How Do I Calculate Time and Fuel for Each Leg?

Distance comes from your plotter. Time is distance divided by groundspeed. Fuel burn is time multiplied by your hourly fuel consumption rate.

For a leg of 42 nautical miles at 102 knots groundspeed:

• Time: 42 ÷ 102 = ~25 minutes
• Fuel burn at 8.5 gallons/hour: approximately 3.5 gallons

Repeat this for every leg. Then total everything: cumulative distance, total estimated time en route, total fuel burn.

How Do I Verify Fuel Reserves Are Legal?

Compare your total fuel burn against actual fuel on board — not maximum tank capacity. Under 14 CFR 91.151, day VFR flights require enough fuel to reach the destination plus a 30-minute reserve at normal cruise.

If your total burn is 18 gallons and you have 40 gallons usable on board, you have 22 gallons remaining — roughly 2.5 hours of reserve. That’s comfortable. But if someone flew the airplane before you and didn’t refuel, you might have 37 gallons instead of a full 56. Your nav log only catches that discrepancy if you enter the real number from your preflight fuel check.

How Do I Use the Nav Log In Flight?

Record your estimated time of departure in Zulu. Every checkpoint arrival time cascades from there. If you depart at 1430Z and your first leg is 25 minutes, you should reach your first checkpoint at 1455Z.

As you pass each checkpoint, write down the actual time of arrival and compare it to your estimate. Consistent late arrivals signal a stronger headwind than forecast, which means higher fuel burn per mile and a shrinking reserve.

Example scenario: You planned a three-leg cross-country — 1 hour 40 minutes total, 14 gallons fuel burn, 36 gallons on board. You arrive 4 minutes late at checkpoint one and 5 minutes late at checkpoint two. You’re 9 minutes behind. Your actual groundspeed is closer to 85 knots than the planned 102. Total flight time jumps to nearly 2 hours, and fuel burn rises from 14 to roughly 17 gallons. Still legal, still safe — but the trend matters. On a tighter plan, those 9 minutes could turn a comfortable arrival into an uncomfortable fuel situation.

The nav log exists not to be right, but to catch when you’re wrong.

What Do Examiners Look for on Checkride Day?

The examiner reviews your completed nav log before you start the engine. They want:

• Neat, legible work completed in pencil (not pen — things change)
• Correct values with math that adds up
• Evidence that you checked weather and NOTAMs
• Separate weight and balance calculations
• Solid fuel planning with real fuel-on-board numbers

Expect questions like: What’s your magnetic heading on leg two? What’s your estimated fuel remaining at the destination? What’s your highest required altitude along the route? If you can’t answer by looking at your nav log, it didn’t do its job.

Bring a clean blank nav log form. Some examiners will ask you to plan a diversion in flight. You won’t build a full nav log airborne, but you’ll estimate a heading, distance, time, and fuel to a diversion airport using the same process in compressed form. That skill comes from having done it on paper enough times that the process is second nature.

Where Can I Learn More?

The complete nav log process is covered in the Pilot’s Handbook of Aeronautical Knowledge, Chapters 15 and 16. Your airplane’s Pilot’s Operating Handbook provides the performance data — true airspeed, fuel consumption, and weight and balance — that feeds into every calculation.

Key Takeaways

• A nav log is a prediction — you build it to compare against reality in flight and catch deviations early
• The heading chain (true course → true heading → magnetic heading → compass heading) is the core skill examiners test
• Use actual fuel on board, not maximum capacity, when calculating reserves
• Track actual vs. estimated times at every checkpoint — consistent delays signal stronger headwinds and higher fuel burn
• Fill out your nav log in pencil and bring a blank form for potential diversions on checkride day