15.pilotage-and-dead-reckoning. Pilotage and Dead Reckoning
Pilotage and dead reckoning are the two foundational visual navigation methods every pilot learns. They are typically used together on a VFR cross-country flight, with each compensating for the weaknesses of the other. Mastery of these techniques is required by the FAA before a student progresses to radio navigation and GPS, because they remain the primary backup when electronic systems fail.
Pilotage
Pilotage is navigation by reference to visible landmarks. The pilot selects prominent features along the planned route — towns, rivers, highways, railroads, lakes, towers, and distinctive terrain — and tracks progress by visually identifying them on a sectional chart. Pilotage works best at low to moderate altitudes where ground detail is clear and over terrain rich in unique features.
Good checkpoint selection is essential:
- Choose features that are unique and unmistakable (a single tower among many is a poor choice; a bend in a river next to a town is excellent).
- Space checkpoints roughly every 10–15 NM, or about every 5–10 minutes of flight, so corrections can be made before drift becomes large.
- Prefer features visible from multiple directions and altitudes (lakes, large highways, rail intersections).
- Avoid relying solely on linear features that parallel your course — they make lateral drift hard to detect.
Pilotage breaks down over featureless terrain (open water, dense forest, desert, snow cover) and at night or in reduced visibility. In those conditions, dead reckoning carries the navigation load.
Dead Reckoning
Dead reckoning (DR) is navigation by computation: using a known starting point, a measured true course, a forecast wind, and the airplane's true airspeed, the pilot calculates the heading to fly and the groundspeed and estimated time en route (ETE) to the next checkpoint. The work is done before takeoff on a navigation log using an E6B or electronic flight computer, and is updated in flight as actual winds reveal themselves.
The core relationships are:
- True Course (TC) — direction of the line between two points on the chart, measured from true north.
- Wind Correction Angle (WCA) — angle the airplane is crabbed into the wind to maintain TC.
- True Heading (TH) = TC ± WCA.
- Magnetic Heading (MH) = TH ± magnetic variation (east is least, west is best).
- Compass Heading (CH) = MH ± deviation (from the compass correction card).
- Groundspeed (GS) = TAS adjusted for the headwind/tailwind component.
- ETE = distance ÷ groundspeed.
- Fuel required = ETE × fuel burn rate, plus reserves.
Example
Planned leg: TC 090°, distance 60 NM, TAS 110 kt. Forecast wind 360° at 20 kt. Variation 8°W. From the wind triangle, WCA is roughly +10° (right crab into the north wind) and GS is approximately 108 kt.
- TH = 090 + 10 = 100°
- MH = 100 + 8 = 108°
- ETE = 60 ÷ 108 × 60 ≈ 33 minutes
The pilot flies a compass heading of about 108° (after applying any deviation) and expects to reach the next checkpoint in 33 minutes.
Combining the Two
In practice, the pilot flies the calculated heading from dead reckoning while verifying position by pilotage. At each checkpoint:
- Note the actual time over the checkpoint and compare to the ETA.
- Compute actual groundspeed from time and distance flown.
- Revise the ETA to destination and recompute fuel remaining.
- If the airplane is left or right of course, apply a correction. A useful rule is the double-the-error method: if you are 2 NM off course after 30 NM, turn into the wind by twice the error angle until back on course, then halve the correction to maintain track.
Lost Procedures
If checkpoints stop appearing where expected:
- Maintain the planned heading and note the time — do not start randomly turning.
- Climb if possible to extend visual range and improve radio reception.
- Cross-reference any visible landmark against the chart.
- Use available aids: VOR cross-bearings, GPS, or contact ATC on 121.5 MHz for assistance.
Why It Still Matters
Even in the GPS era, the FAA requires demonstrated proficiency in pilotage and dead reckoning on the private pilot practical test. They are the backup when the magenta line disappears, they sharpen situational awareness, and they force the pilot to think about wind, time, and fuel — the variables that ultimately decide whether a flight ends safely.