Commercial Pilot ACS Study Guide: Pilotage and Dead Reckoning

Modern navigation technology makes it easy to follow a magenta line, but a commercial pilot is expected to understand the fundamentals that make that line meaningful.

Pilotage and dead reckoning require you to combine chart interpretation, aircraft performance, weather, wind correction, time, distance, and fuel planning into an accurate picture of where the airplane should be—and then verify that picture in flight.

For the commercial pilot checkride, the goal is not simply to demonstrate that you can reach your destination. You should be prepared to explain how you planned the flight, why you selected your route and checkpoints, and how you would recognize and correct a deviation.

**What Is Pilotage? **

Pilotage is navigation by reference to visible landmarks and their relationship to features depicted on an aeronautical chart.

Useful checkpoints may include:

• Airports
• Cities and towns
• Highways and major roads
• Rivers, lakes, and reservoirs
• Railroad tracks
• Mountain ranges or prominent terrain
• Other easily identifiable charted features

A good checkpoint should be distinctive, visible, and easy to positively identify from the air.

Avoid relying on small or ambiguous landmarks that could easily be confused with something else.

Commercial Pilot Tip

Don’t just identify a checkpoint—be prepared to explain why you chose it. Consider visibility, terrain, airspace, altitude, and whether the feature can reasonably be identified from your planned route.

**What Is Dead Reckoning? **

Dead reckoning determines position based on calculations involving direction, time, speed, distance, and wind.

Before departure, you calculate where the aircraft should be based on factors such as:

• True course
• Wind direction and velocity
• Wind correction angle
• True heading
• Magnetic variation
• Magnetic heading
• True airspeed
• Groundspeed
• Distance
• Estimated time en route
• Fuel consumption

In flight, you compare those calculations with what is actually happening.

If a checkpoint was expected after 12 minutes but appears after 15, that difference tells you something. Your groundspeed may be lower than planned, the winds may differ from the forecast, or your original calculation may need to be reevaluated.

Pilotage + Dead Reckoning

These two methods are most effective when used together.

Dead reckoning predicts where you should be.

Pilotage confirms where you actually are.

A commercial pilot should continuously compare the two rather than blindly relying on either method.

For example, if your calculations predict that you should cross a reservoir at 10:20, but the reservoir is still several miles ahead at that time, recognize the discrepancy and determine why before it develops into a larger navigation, fuel, or situational-awareness problem.

**Selecting the Route **

The shortest route is not automatically the best route.

Route planning should account for:

• Airspace
• Terrain and obstacles
• Weather
• Winds
• Airport availability
• Emergency landing options
• Navigation checkpoints
• TFRs and NOTAMs
• Aircraft performance
• Fuel requirements

A slightly longer route may provide better terrain clearance, more recognizable checkpoints, improved emergency options, or easier airspace management.

A DPE may ask:

“Why did you choose this route?”

Your answer should demonstrate aeronautical decision-making—not simply that it was the straightest line between two airports.

**Selecting Altitude **

Cruising altitude affects much more than regulatory compliance.

Consider:

• Terrain and obstacles
• Airspace
• Winds aloft
• Aircraft performance
• Visibility and cloud clearance
• Outside air temperature
• Density altitude
• Emergency landing options
• Fuel consumption

Higher is not always better, and lower is not always faster. Select an altitude that makes sense for the conditions and be prepared to defend your decision.

**Selecting Checkpoints **

Checkpoints should be spaced closely enough to provide meaningful position verification throughout the flight.

Look for features that are:

Large. Easy to see from your planned altitude.

Distinctive. Difficult to confuse with another feature.

Charted. Clearly represented on the navigation chart.

Near the route. You should not need to make significant deviations simply to identify them.

Pay particular attention to how the checkpoint will look from the air, not just how obvious it appears on a sectional chart.

**Plotting the Course **

A commercial applicant should understand the calculations behind the planned flight rather than relying entirely on an electronic flight planning application.

The basic process moves from your desired course to the heading you actually need to fly.

True Course → Wind Correction → True Heading → Variation → Magnetic Heading

Remember that course describes the intended path across the ground, while heading describes where the aircraft’s nose is pointed.

Wind is the reason those numbers may not be the same.

**Wind Correction Angle **

A crosswind pushes the airplane away from its intended ground track unless the pilot compensates for it.

The wind correction angle (WCA) is the correction applied to the aircraft’s heading to maintain the desired course.

Think of it this way:

Heading controls where the nose points.
Course describes where the airplane travels over the ground.

With a crosswind, the aircraft must be pointed slightly into the wind to maintain the planned course.

**Time, Speed, and Distance **

Know the basic relationship:

Distance = Groundspeed × Time

From that relationship:

Time = Distance ÷ Groundspeed

Groundspeed = Distance ÷ Time

Remember that navigation calculations use groundspeed, not simply indicated or true airspeed.

A 110-knot true airspeed does not necessarily mean the airplane covers 110 nautical miles in one hour. A headwind decreases groundspeed, while a tailwind increases it.

**True Airspeed and Density Altitude **

As altitude and density altitude increase, true airspeed differs increasingly from indicated airspeed.

Understanding this relationship matters because true airspeed is used when solving the wind triangle, while groundspeed ultimately determines your actual progress across the ground.

A commercial pilot should be able to explain how atmospheric conditions influence:

• True airspeed
• Groundspeed
• Aircraft performance
• Fuel planning
• Estimated time en route

Don’t treat navigation and aircraft performance as separate subjects—they directly affect one another.

**Magnetic Compass Errors **

Be prepared to discuss the limitations of the magnetic compass, including:

• Variation
• Deviation
• Magnetic dip
• Northerly turning error
• Acceleration and deceleration errors
• Oscillation

Electronic navigation equipment may be available, but the ACS still expects the commercial applicant to understand and properly use magnetic direction information.

**Topography **

Reading terrain on a sectional chart is an important part of both navigation and risk management.

Understand features such as:

• Contour lines
• Maximum elevation figures
• Spot elevations
• Mountain passes
• Towers and obstacles
• Terrain shading

Terrain awareness should influence route selection, altitude, checkpoint selection, and emergency planning.

This becomes especially important when flying in mountainous areas or regions where rapidly rising terrain limits diversion and emergency landing options.

**Power Setting Selection **

Your planned cruise performance should come from the aircraft’s approved performance information—not a guess based on what the airplane “normally does.”

Know how your selected power setting affects:

• Cruise speed
• Fuel burn
• Range
• Endurance
• Engine operation
• Time en route

If your flight planning assumes a particular cruise speed and fuel burn, you should understand what power setting produces those numbers.

**Planned vs. Actual **

One of the most important commercial-level concepts is recognizing when the flight is not progressing according to plan.

During the flight, compare:

Planned groundspeed vs. actual groundspeed

Planned ETA vs. actual progress

Planned fuel consumption vs. actual fuel remaining

Planned course vs. actual position

If the numbers do not agree, don’t simply continue with the original plan.

Determine what changed and recalculate.

A stronger-than-forecast headwind, for example, doesn’t only affect arrival time. It can also change your fuel reserves and potentially whether continuing to the destination remains a good decision.

Risk Management

Pilotage and dead reckoning require significant attention inside and outside the cockpit. The ACS specifically addresses collision hazards, distractions, task prioritization, loss of situational awareness or disorientation, and unplanned fuel or power consumption.

Avoid becoming so focused on charts, calculations, or avionics that you stop flying the airplane or maintaining an effective outside scan.

A useful priority remains:

Aviate → Navigate → Communicate

Navigation is important, but aircraft control and situational awareness always come first.

Checkride Preparation

Before your commercial practical test, make sure you can confidently:

• Prepare and use a flight log
• Explain pilotage and dead reckoning in practical terms
• Select and identify effective checkpoints
• Explain why you selected your route and altitude
• Calculate headings, groundspeed, time, distance, and fuel
• Apply wind correction
• Explain true versus magnetic direction
• Discuss magnetic compass errors
• Interpret terrain and topographic information
• Compare planned performance with actual results
• Recalculate when conditions differ from the original plan
• Maintain awareness of your position throughout the flight

The ACS requires the applicant to verify the aircraft’s position within two nautical miles of the flight-planned route.

Final Takeaway

Pilotage and dead reckoning are not outdated skills—they are the foundation of understanding how an airplane moves through the atmosphere and across the ground.

For the commercial pilot, the standard goes beyond following a planned route. You should understand the calculations behind it, recognize when reality differs from the plan, and make timely corrections based on the information available.

Use technology as a resource, but make sure you understand the navigation principles operating behind the screen.

FAA References

• Commercial Pilot for Airplane Category Airman Certification Standards, FAA-S-ACS-7B
• Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25C, Chapter 16 — Navigation
• Airplane Flying Handbook, FAA-H-8083-3C
• FAA VFR Navigation Charts