IFR flight planning has gotten complicated with all the apps and digital tools flying around. As someone who still practices manual nav log calculations, I learned everything there is to know about Jeppesen IFR nav logs and why they’re not obsolete. Paper flight planning still matters. Here’s why.
What’s Actually On the Form
A Jeppesen nav log breaks your flight into waypoint-by-waypoint segments. Each leg gets distance, course, wind data, fuel burn, and timing calculations. Cumulative totals run at the bottom — total fuel required, total flight time, estimated arrival. That’s what makes these forms endearing to us planning nerds — everything you need for a safe flight, organized on one sheet.
ATC cares about your total fuel and ETA. The nav log is how you derive those numbers from first principles rather than blindly trusting an app.
Why Paper When We Have ForeFlight?
Probably should have led with this section, honestly. ForeFlight and similar apps do the calculations automatically. So why bother with manual planning?
First: manual planning forces you to think through the flight. You catch errors that apps don’t flag. Understanding the math means understanding what the numbers actually mean.
Second: checkrides. DPEs expect manual planning proficiency. Oral exams drill into the math. You can’t just say “my iPad figured it out.”
Third: backup. Batteries die. GPS units fail. Screens crack. Paper doesn’t need a power source. When technology fails at flight level 250, you’ll be glad you know how to work a nav log.
The Math (Quick Version)
Start with true course from your chart. Calculate wind correction angle using an E6B or electronic calculator. True heading equals true course plus WCA.
Apply magnetic variation to get magnetic heading. Apply compass deviation to get compass heading. Sounds complicated, but it becomes automatic with practice.
Ground speed comes from the E6B. Time equals distance divided by ground speed. Fuel equals time times burn rate. Simple arithmetic that keeps you alive.
Where People Mess Up
Forgetting fuel reserves. The FARs specify minimums, but smart pilots plan well beyond those. Running a tank dry because you calculated to the FAA minimum is technically legal but deeply stupid.
Using wrong magnetic variation. It changes across the country and it changes over time. Check each waypoint individually.
Ignoring winds aloft. At altitude, winds are significant. A 50-knot headwind changes your fuel picture dramatically. Always get current forecasts.
The Modern Approach
File what ForeFlight generates. Carry a paper nav log as backup. Cross-reference for errors. The hybrid approach gives you the best of both worlds — digital efficiency with manual verification. I’ve caught ForeFlight errors this way. Not often, but once is enough to justify the habit.
