Lesson 7.1 Pilotage & Dead Reckoning

Lesson 7.1 – Pilotage & Dead Reckoning

Pilotage and dead reckoning are the foundational methods of VFR navigation. Even when GPS is available, every pilot must be proficient in these skills. These topics are tested on the FAA Private Pilot knowledge exam.

Reference:

FAA Pilot’s Handbook of Aeronautical Knowledge (PHAK), Chapter 16 – Navigation

Pilotage

Pilotage is navigation by reference to visible landmarks on the ground. Choose checkpoints that are unique and easy to identify from the air (roads, rivers, towns, distinctive towers, etc.). Select checkpoints roughly 10–15 minutes apart when possible.

Dead Reckoning

Dead reckoning is navigation by calculating direction and distance from a known position using heading, speed, and time.

Basic relationship:

Distance = Speed × Time

Key terms for the written exam:

True Course (TC) – Direction measured on the sectional chart with a plotter.
Magnetic Course – True Course corrected for magnetic variation.
Magnetic Heading – Magnetic Course corrected for wind.
Compass Heading – Magnetic Heading corrected for deviation.
Groundspeed – Actual speed over the ground.
True Airspeed (TAS) – Speed of the airplane through the air.

True North vs. Magnetic North

True North points to the Geographic North Pole.
Magnetic North is the direction a magnetic compass points.
The difference between them is called magnetic variation.

Sectional charts are drawn with reference to True North. When you measure a course on the chart, you obtain a True Course. You must apply magnetic variation to convert it to a Magnetic Course.

VOR radials are oriented to Magnetic North, not True North.

Magnetic Variation and Isogonic Lines

Magnetic variation is shown on sectional charts by dashed magenta lines called isogonic lines. Each line is labeled with the amount of variation and whether it is East or West (example: 5°E or 12°W). The line of zero variation is called the agonic line.

In the United States:

West of the agonic line → variation is generally Westerly
East of the agonic line → variation is generally Easterly

Rule for converting True Course to Magnetic Course:

East is least, West is best.

Easterly variation → Subtract
Westerly variation → Add

Examples:

True Course 090° with 7° East variation → Magnetic Course = 083°

True Course 090° with 7° West variation → Magnetic Course = 097°

Magnetic Deviation

Deviation is the error caused by magnetic fields inside the airplane (radios, engine, electrical equipment, metal structure, etc.).

Deviation is different on every heading and in every airplane.
It is recorded on a compass correction card mounted near the magnetic compass.
The card tells you what compass heading to steer to achieve a desired magnetic heading.

Order of Corrections (Important for the Written Exam)

True Course (measured on the chart)
Apply Variation → Magnetic Course
Apply Wind Correction → Magnetic Heading
Apply Deviation → Compass Heading

Tools Required for the Knowledge Test

Plotter – Measures true courses and distances on the sectional chart.
Mechanical Flight Computer (E6B) – Solves time/speed/distance, wind correction, true airspeed, density altitude, and fuel problems.

Important: Electronic devices and phone apps are generally not allowed on the FAA knowledge test. You must know how to use the mechanical E6B and a paper plotter.

Combining Pilotage and Dead Reckoning

Measure True Course and distance on the chart with a plotter.
Apply magnetic variation to obtain Magnetic Course.
Use the E6B to calculate wind correction, heading, groundspeed, and time.
Apply deviation from the compass card to get Compass Heading.
Use visual checkpoints (pilotage) to confirm you are on course and on time.

Key Points for the Written Exam

Courses measured on sectional charts are True.
VOR radials are Magnetic.
East variation is subtracted; West variation is added (“East is least, West is best”).
Deviation is found on the airplane’s compass correction card.
Know the correct order: True → Variation → Magnetic → Wind → Heading → Deviation → Compass.
You must be able to use a plotter and mechanical E6B.

Key Points for the Written Exam

Courses measured on sectional charts are True.
VOR radials are Magnetic.
East variation is subtracted; West variation is added (“East is least, West is best”).
Deviation is found on the airplane’s compass correction card.
Know the correct order: True → Variation → Magnetic → Wind → Heading → Deviation → Compass.
You must be able to use a plotter and mechanical E6B.