How to read a VFR nav log, column by column

Updated

A nav log looks like a wall of abbreviations until you know that every row answers the same few questions. Where am I going, which way do I point, how fast do I go, how long does it take, and what is left in the tanks. This guide goes through the columns of an AirPlotter nav log in the order they appear, and says which ones you look at in the cockpit.

One row for each leg

Each row is a leg, and it is named after the point where the leg ends. So the row called LETO describes the flight from the previous point to LETO. The first row is the departure, with the take-off time and the fuel you have after taxi.

Between the legs you will see a few computed rows. TOC is the top of climb, TOD is the top of descent and BOD is the bottom of descent. They mark the places where the profile changes, and AirPlotter puts them there for you. If you plan an alternate, the leg to it has its own shaded row.

The navigation columns

Alt is the planned altitude in feet. An arrow beside it shows that you climb or descend on that leg.

Wind is the direction the wind blows from, in degrees true, and its speed in knots. It is the forecast for that leg's altitude and time.

OAT is the outside air temperature in degrees Celsius, with its difference from the standard atmosphere (ISA) beneath it. A warm day shows a positive number.

TC and WCA are the true course of the leg and the wind correction angle, which is how far you turn into the wind to stay on the course. Wind correction angle and ground speed explains where the number comes from.

TH and Var are the true heading, which is the course corrected for the wind, and the magnetic variation of the leg with its direction, such as 1°E or 1°W.

MH is the magnetic heading, the heading to fly on the compass. It is the true heading corrected for the variation, and it is the one number of the navigation group that you read in flight.

TAS and GS are the true airspeed and the ground speed, in knots. The TAS is a figure of your aircraft. The ground speed is what the wind makes of it, and it is the figure that sets your timing.

Distance and time

Dist shows the length of the leg in nautical miles, and under it the total from the departure.

ETE is the estimated time en route: the minutes of the leg, with one decimal, and under it the total so far in hours and minutes.

ETO is the estimated time over the point, in UTC and rounded to the minute. It is the figure you compare against your watch to know whether you are early or late.

Fuel

The Fuel column shows the fuel burned on the leg and the fuel left after it, in the unit you set for the aircraft. The last row shows what you land with. For how the amounts are made, read the guide to VFR fuel planning.

Radio and airspace

Freq lists the frequencies you need to have ready on that leg. The ones to call come first, with the ATIS first and then ground, tower, information and approach. The ones to listen on come after them, marked MON, and then your own frequencies. When a row has more than fit, a button shows the rest.

Airspace names the airspaces that the leg flies through. NOF marks a no-overflight zone, and an exclamation mark means the airspace is not open to VFR, so you do not enter it.

The columns to fill in flight

The last three columns are blank, and the cells are highlighted so you can write in them with a pen: ATO is the actual time over the point, ATE is the actual time en route and AFR is the actual fuel remaining. Comparing them with ETO, ETE and the fuel left shows you early whether a wind is stronger than forecast.

Full, Standard and Minimal

The nav log opens with all the columns, called Full. When that is more than you want in the cockpit, switch the preset:

  • Standard is Full without OAT, TAS and TH, which are planning figures you do not read in flight.
  • Minimal is the waypoint, MH, GS, ETE, ETO, the frequencies and airspace, and the three write-in columns. It is what you need to fly the route.

The waypoint column is always there. If you tick or untick a column by hand, the preset shows Custom until you choose one again.

What to look at in the air

In flight you read only a few columns: the waypoint you are going to, the MH to fly, the ground speed and ETO to check your progress, the frequencies to call and the airspace ahead. The rest are the working that led to those numbers, and they are there so you can check the plan on the ground.

To try it, add a route in the planner, open the nav log and look at each column against this guide.