Pilotage and Dead Reckoning

Tighter than the private standard across the board. You must:

• Verify position within two nautical miles of the flight-planned route (CA.VI.A.S5)
• Arrive at en route checkpoints within three minutes of the initial or revised ETA, and provide a destination estimate (CA.VI.A.S6)
• Maintain the selected altitude ±100 feet and heading ±10° (CA.VI.A.S7)

The three-minute window is against the initial or revised ETA — so a revised estimate you announce and then hit is a pass, not a save. Revising early is the professional move.

Dead reckoning is navigation "solely by means of computations based on time, airspeed, distance, and direction" — the products, adjusted for wind, are heading and groundspeed (PHAK 16-13). Pilotage confirms it: PHAK notes the heading and GS as calculated are "constantly monitored and corrected by pilotage as observed from checkpoints."

What changes for the commercial ride is the loop rate. You are not just confirming you are on course — you are extracting a revised groundspeed at every checkpoint and pushing a revised ETA and fuel burn forward to the destination before anyone asks.

• Variation — the angular difference between true and magnetic north; applied from the isogonic lines on the chart (PHAK 16-7).
• Deviation — error from the airplane's own magnetic fields; unlike variation it depends on heading, and you read it off the compass correction card (PHAK 8-25).
• Northerly turning error — the compass leads or lags in turns near north/south. Rule of thumb: roll out 15° plus half your latitude early on a northerly turn, and the same amount late on a southerly turn (PHAK 8-25).
• Acceleration error — ANDS: Accelerate-North, Decelerate-South, on easterly and westerly headings (PHAK 8-26).
• Oscillation — a combination of all the above; use the average of the swings when setting the heading indicator (PHAK 8-27).

Choose easy-to-locate points — large towns, large lakes and rivers, or combinations of recognizable points, ideally towns with an airport or with a highway and railroad network. Normally pick only towns shown as splashes of yellow on the sectional; do not pick towns drawn as a small circle, because "these may turn out to be only a half-dozen houses" (PHAK 16-18).

Commercial delta: pick checkpoints that also give you a usable groundspeed leg. A checkpoint five miles after the last one produces a groundspeed number with enormous error. Space them so each leg is long enough that the time you record means something.

Topography: the sectional is a topographic chart before it is an aeronautical one — it carries "airport data, navigational aids, airspace, and topography" at a scale of 1:500,000 (1 inch ≈ 6.86 NM), portraying relief and a judicious selection of visual checkpoints for VFR flight; a VFR terminal area chart at 1:250,000 gives a more detailed display of topographical information (PHAK 16-2).

Planning use: study the terrain and obstructions along the route to determine the highest and lowest elevations and the highest obstruction you will meet, so you can pick an altitude that conforms to part 91. Check the route for particularly rugged terrain so it can be avoided, and check departure and arrival areas for tall obstructions — television transmitting towers "may extend to altitudes over 1,500 feet above the surrounding terrain" (PHAK 16-18).

• Maximum elevation figures (MEFs) — the bold numbers in each quadrangle. PHAK 2-9 says to "use maximum elevation figures (MEFs) and other easily obtainable data to minimize chances of an inflight collision with terrain or obstacles."
• Relief portrayal and obstruction symbology — read them off the chart legend. PHAK 16-2 notes that "by referring to the chart legend, a pilot can interpret most of the information on the chart," and that the pilot should also check the legend for other information such as ATC frequencies and airspace.
• Plan the altitude on the ground. PHAK 2-9: "to avoid terrain and obstacles, especially at night or in low visibility, determine safe altitudes in advance by using the altitudes shown on VFR and IFR charts during preflight planning."

The part 91 hook worth saying out loud: if the flight is flown more than 3,000 feet above the terrain, the hemispheric cruising altitude appropriate to your magnetic course is required (PHAK 16-18).

Four things you should be able to say out loud:

• Terrain and obstacle clearance
• Winds aloft — the altitude that buys the best groundspeed for the fuel burned
• Cloud clearance and visibility under the VFR minimums for the airspace
• Radio and navigation reception — VOR signals are line-of-sight; PHAK 16-23 notes the flag comes up when the airplane is too far from the station "or the aircraft is too low"

Add the cruising-altitude rule for the magnetic course you are flying, and the fact that a higher altitude also extends radar coverage if you need help later (PHAK 16-34).

Off the AFM/POH cruise performance chart for your pressure altitude and temperature, then leaned per the POH procedure. PHAK puts the responsibility plainly: preflight planning "should be supported by proper monitoring of past fuel consumption as well as use of specified fuel management and mixture adjustment procedures in flight" (PHAK 16-11), and "for simple aircraft with reciprocating engines" the AFM/POH "provides gallons-per-hour values to assist with preflight planning" (PHAK 16-12).

The examiner cares because the whole flight log — TAS, groundspeed, ETAs, fuel remaining — is built on the power setting you picked. Fly a different setting than you planned and every number downstream is wrong.

For airplanes under VFR you may not begin a flight unless — considering wind and forecast weather — there is enough fuel to fly to the first point of intended landing and, at normal cruising speed, to fly after that for at least 30 minutes by day or 45 minutes by night (91.151).

Treat that as the floor, not the plan. On the commercial ride the useful question is the one the examiner will ask in the air: given the groundspeed you just measured, what is your fuel over the destination? If the answer is trending toward the reserve, the correct answer is a fuel stop or a diversion — see Task VI.C.

Recompute, don't rationalize. Steps in the cockpit:

1. Groundspeed: distance flown divided by actual elapsed time (PHAK 16-11, GS = D/T).
2. Wind correction: if you are also displaced laterally, correct back toward course and add drift correction so you stay within 2 NM of the planned route (CA.VI.A.S5).
3. Revise the ETAs for the remaining checkpoints and the destination on the new groundspeed, and say the new numbers.
4. Revise the fuel: new time en route times your known burn, checked against the gauges and the clock.

A revised ETA you then meet within three minutes satisfies CA.VI.A.S6.

Before beginning the flight the PIC must become familiar with all available information concerning that flight. For a flight not in the vicinity of an airport, that includes:

• Weather reports and forecasts
• Fuel requirements
• Alternatives available if the planned flight cannot be completed
• Any known ATC traffic delays

For any flight, it also includes runway lengths at airports of intended use and the AFM takeoff and landing distance data (91.103).

Note the phrase "alternatives available if the planned flight cannot be completed" — diversion planning is a regulatory preflight item, not just good airmanship.

The head-down time is the hazard. Managed by:

• Ground work stays on the ground — courses, distances, checkpoints, and waypoints entered before takeoff. PHAK 16-33 warns to enter user-defined waypoints "prior to flight, not on the fly."
• Look outside between computations. PHAK's own guidance for cockpit computation is to "take advantage of all possible shortcuts and rule-of-thumb computations" precisely because attention must be divided between flying, computing, and scanning (PHAK 16-34).
• Use ATC — VFR radar traffic advisories from an approach or center facility (PHAK 14-26), covered in Task VI.B.
• Aviate first. PHAK 16-35: "Give priority to flying the aircraft while dividing attention between navigation and planning."

• Time: T = D ÷ GS. 210 NM at 140 knots is 210 ÷ 140 = 1.5 hours, i.e. 1:30.
• Distance: D = GS × T. 1 hour 45 minutes at 120 knots is 120 × 1.75 = 210 NM.
• Groundspeed: GS = D ÷ T. 270 NM in 3 hours is 90 knots.

Minutes to hours: divide by 60. Hours to minutes: multiply by 60 — 0.75 hour is 45 minutes (PHAK 16-11).

Cockpit shortcut worth having: at 120 knots groundspeed you cover 2 NM per minute, so miles-to-go divided by two is minutes-to-go. Scale from there.

"A wind triangle, the pilot's version of vector analysis, is the basis of dead reckoning" — a graphic explanation of the effect of wind upon flight, from which "GS, heading, and time for any flight can be determined" (PHAK 16-13).

Three vectors:

• Wind — direction and speed
• Air vector — true heading and TAS
• Ground vector — true course and groundspeed

You know the true course off the chart, the TAS off the POH, and the wind from the forecast — solve for the other two. On the ride you do it on a flight computer or an E6B app, not with a pencil, but you must be able to say what it is solving.

PHAK 16-9 names the pieces: heading is where the nose points, track is the actual path over the ground, and the angle between them is the drift angle.

PHAK 16-16 gives the chain and the signs:

• TC — the course line measured clockwise from true north on the mid-meridian.
• ± WCA → TH. The wind correction angle comes from the wind triangle and is expressed in degrees right or left of the TC: added to TC if the wind is from the right, subtracted if the wind is from the left.
• ± variation → MH. Off the isogonic line: added to TH if west, subtracted if east.
• ± deviation → CH. Off the compass correction card in the airplane.

Then GS comes off the same triangle, total distance off the chart scale, and ETE = distance ÷ GS (PHAK 16-16 to 16-17). Get the WCA wrong and you are off course; get the GS wrong and every ETA and fuel number is wrong.

Because it moves both halves of the dead reckoning problem. Density altitude is pressure altitude corrected for nonstandard temperature; PHAK 8-7 works the example of a field at 5,048 feet MSL where standard temperature is 5 °C — pressure altitude and density altitude are both 5,048 feet, but at 30 °C the density altitude rises to 7,855 feet, and at −25 °C it falls to 1,232 feet.

Consequences for the leg: at higher density altitude a normally aspirated engine makes less power, so the cruise TAS and fuel flow you read off the POH chart must be taken at the actual pressure altitude and temperature, not the planned ones. Get the TAS wrong and every ETA on the log is wrong before you take off.

The skill element asks you to use the magnetic direction indicator in navigation, including turns to headings — which in practice means flying a heading with the heading indicator failed or caged.

• Set up the turn at a standard rate and apply the northerly turning error correction: roll out 15° plus half your latitude before the desired heading on northerly headings, and the same amount past it on southerly headings (PHAK 8-25).
• East and west roll out on the number — there is no turning error there, but expect the acceleration error (ANDS) if you change airspeed on those headings (PHAK 8-26).
• Let the card settle in wings-level, unaccelerated flight before you believe it; PHAK 8-27 notes oscillation is a combination of all the errors, and you should use the average indication between swings.

Prepared on the ground:

• Leg distances, true course, wind correction angle, true heading
• Variation and deviation to a compass heading
• TAS and planned groundspeed
• Leg times and cumulative times
• Fuel burned versus fuel remaining

PHAK 16-17 also lists the underlying preflight material — current sectional plus adjoining charts, computer or calculator, plotter, plus the Chart Supplement and NOTAMs for each airport of intended landing.

Used in flight: a time recorded at every checkpoint. That single habit produces actual groundspeed, the revised ETA, the revised fuel, and — if you ever lose the picture — the last known position that Task VI.D is built on.

PHAK 16-17 warns the chart "may be up to 6 months old"; the effective date is printed at the top of the front. So:

• Check the Chart Supplement U.S. for the latest airport information — it "should be used in preference to the information on the back of the chart, if there are differences."
• Check NOTAMs, issued every 28 days, for hazardous conditions or changes since the Chart Supplement was issued.
• Check the sectional chart bulletin for major changes since the chart's publication date.

Same discipline applies to the EFB in your lap — currency of the underlying data is the pilot's problem, not the app's. See Task VI.B.