16.3 Lost Procedures and Diversion

ACS PA.VI.D is lost procedures: methods to determine position, and assistance available (radar, communications). PA.VI.C is diversion: select an alternate and get there with heading, time, and fuel. PA.I.D.K6 intercepts were introduced in 15.4; this section adds the AIM 5-6 visual signals you must not invent.

You are not sure where you are

PHAK Chapter 16: if a town or city cannot be seen, the first thing to do is climb, mindful of traffic and weather. Height buys a longer visual horizon, VHF line-of-sight, VOR reception, and a better chance Approach can paint you. ACS PA.VI.D.S2 is the same idea: maintain an appropriate heading and climb as necessary. Hold the last good heading. Random 20° “corrections” turn a 4-mile miss into a 15-mile mystery.

Schools teach the 4 Cs as a memory stack that matches that PHAK/ACS sequence:

1. Climb — if ceiling, airspace, and fuel allow. Circle in place if you must climb through a layer of landmarks you have not identified yet; do not cruise deeper into the unknown.
2. Confess — say the words: “uncertain of position.” Denial is how people fly into a TFR they would have been vectored around.
3. Comply — fly the heading, altitude, and frequency you are given. Read them back.
4. Conserve — best-endurance power and mixture once you are level, until you have a field and a time. Fuel is the clock.

Communicate is often inserted as a fifth C (climb, communicate, confess, comply, conserve) because ACS PA.VI.D.K2 is assistance: ATC, Flight Service, 121.5. Call the facility you were already talking to. If you were on flight following, you are already a discrete code — ask for a position and a heading. If you were not, try Approach, Center, or Flight Service on the charted frequency, then 121.5. If it is an emergency (fuel, weather, night with no field), squawk 7700 and say so. 7600 is lost comm, not lost nav.

Then actually find yourself (PA.VI.D.K1 / S1 / S3):

• Reset the heading indicator to the compass in straight, unaccelerated flight.
• Orient the sectional to the heading.
• Match a unique landmark — a shoreline, a T-shaped lake, a town-plus-rail-plus-highway — not “some fields.”
• Tune and identify a VOR; center FROM to read the radial; a second VOR (or DME) crosses the line into a fix.
• GPS NRST is a method, not a religion. Confirm the airport or VOR it names against the chart before you turn.

The triangle of uncertainty is last known position, plus the time since that fix, plus every degree you might have been off heading or every knot you might have been off groundspeed. After 12 minutes at 100 knots you have flown 20 NM. A 10° heading error is already about 3.5 NM off the planned line, and you do not know which side. The area of possible position is a widening triangle, not a point. That is why 15.2 wanted a checkpoint every 10–15 NM, and why you climb and stop the clock from running farther before you guess.

If you cannot fix yourself, select a course of action (PA.VI.D.S5): radar vector, divert, or — if fuel or weather is collapsing — declare and land. A precautionary landing at a suitable airport beats a forced landing in the last pasture after you “just flew a little farther.”

Diversion — a new plan, not a panic turn

PA.VI.C is what you do when the original destination is no longer the right airport: weather below your personal minimums, a closed runway, fuel that will not make 91.151, a sick passenger, a failed vacuum. Select first:

• Runway long and wide enough for this weight and wind (Chart Supplement, not the tiny sectional number alone).
• Weather you can actually land in (AWOS/ATIS, not the METAR from two hours ago).
• Fuel, services, and lighting if you will arrive late.
• Airspace you can enter (a convenient Class B airport is not convenient without a clearance).

Then compute, even roughly: true course off the chart, variation, a wind guess, a heading, distance, groundspeed, time, fuel at the present flow plus 91.151. GPS direct is a cross-check, not the ACS skill. Communicate: tell ATC or Flight Service the new destination, amend or close the old VFR plan, and call the new CTAF or tower in time to fit the pattern. Write the new ETA. A diversion that “saves” 10 minutes and spends 12 gallons circling the wrong field is not a diversion.

Intercept procedures — AIM 5-6 only

Do not write a Hollywood script. AIM 5-6-13 is the list. Interceptors usually approach from behind, often in pairs. You must, without delay:

1. Adhere to visual devices, visual signals, and radio instructions from the interceptor.
2. Call on guard 121.5 (or 243.0 if you have UHF): identity, position, nature of flight.
3. Squawk 7700 unless ATC instructs otherwise.
4. Keep complying until positively released. If ATC and the interceptor disagree, seek clarification — do not ignore the fighter.

Published visual meanings (AIM TBL 5-6-1 / 5-6-13):

• Interceptor rocks wings (day), from slightly above and ahead, normally to the left, then a slow turn onto a heading — you have been intercepted; follow me. Night: same plus irregular flashing of nav lights. You rock wings (day) or flash nav lights irregularly (night) and follow.
• Interceptor abrupt 90°+ climbing breakaway that does not cross your nose — you may proceed. Acknowledge by rocking wings.
• Interceptor circles the aerodrome, lowers landing gear, and overflies the runway in the landing direction — land at this aerodrome. You lower the gear, follow, overfly the runway, and land if it looks safe. Night: same plus steady landing lights.
• A time-critical divert maneuver is the interceptor crossing your nose (minimum 500 feet, from slightly below) while rocking wings (or flashing lights / afterburner at night). Turn immediately in the direction indicated. A second crossing with flares is a warning to comply now.

Rocking your own wings is the acknowledgment, not a request to negotiate. Prevention remains cheaper: current TFRs, a DVFR plan before an ADIZ, the DC SFRA discrete-code rules from Chapter 5.

PAR scenario: Checkpoint was due 8 minutes ago, no lake, haze, 14 gallons usable, 9.0 gph. Climb 1,000 feet if the ceiling and airspace allow, hold heading, call Approach: “uncertain of position, request radar identification.” If they are silent, 121.5 and, if fuel or weather is the problem, 7700. If they point you at a 5,000-foot paved field 20 NM left, that is a diversion — heading, 12 minutes, about 2 gallons plus reserve — not a random left turn toward a cluster of lights. If the traffic that showed up is a fighter rocking its wings, you are no longer in the lost-procedures lesson: 121.5, 7700, follow.