Section 4: Airport Operations — Patterns, Signs, Beacons, and Reading the Chart Supplement

First split: TOWERED fields have ATC and manned aircraft MUST communicate; UNTOWERED fields have no controller - radio use is recommended, not required, over a shared Common Traffic Advisory Frequency (CTAF, often the UNICOM frequency). Second split: civil (public), military/federal (closed), private (permission required). For a drone pilot the payoff is situational: knowing which kind of field is nearby tells you whether a controller exists to coordinate with and how predictable the traffic will be.

Charts orient to TRUE north (the geographic pole); instruments read MAGNETIC north, which drifts - fast enough lately to make news, per his aside. The angle between them at your location is VARIATION, expressed east or west (his home: ~11 degrees, 'in two or three years, it could be completely different'). Conversion is the classic mnemonic: EAST IS LEAST, WEST IS BEST - subtract easterly, add westerly variation going true-to-magnetic. Isogonic lines on sectionals map the variation, previewed here for the Charts chapter.

Take the MAGNETIC heading, round to the nearest 10 degrees, drop the zero: 180/360 becomes Runway 18/36. Ends differ by 180 degrees - 18 apart in the numbers. Parallels wear L/C/R (and 36R is 18L from the other end); at four-plus parallels one runway's NAME shifts ~10 degrees from its true paint-line heading. Because variation drifts, numbers genuinely change: 040 crept to 044, rounded to 050, and 4/22 was repainted 5/23. The X across a runway means closed. Exam certainty: runway orientation is ALWAYS magnetic, never true.

In order: UPWIND (climbing off the runway - takeoffs and landings run into the wind), CROSSWIND (still climbing, roughly 600-1,000 ft), DOWNWIND (level at 1,000 ft AGL, opposite the landing direction - standard entry is 'midfield downwind'), BASE (descending turn, begun abeam the numbers), FINAL (descent to the runway). Manned pilots typically call about 10 miles out. Direction default: LEFT turns everywhere unless marked - the segmented circle's L-shaped ticks flag right-pattern runways, and the Chart Supplement annotates ONLY right traffic: 'the fact that it doesn't say anything tells us that it is indeed a left traffic.'

WINDSOCK: inflation shows strength (limp = calm, rigid = strong); the tail points DOWNWIND, so read the wind from the opposite end. TETRAHEDRON: the point aims INTO the wind. WIND T: airplane-shaped; the wings face the source, tail downwind. His field-craft additions for drone pilots without an airport: tree movement, dropped grass clippings, wave direction on water - enough to plan a takeoff that won't drift into obstacles.

Signs: BLACK background = location ('you are on Taxiway Alpha 4'), YELLOW = direction to somewhere else. Taxiways are letters, runways two-digit numbers. The HOLD-SHORT line - double yellow, solid plus dashed - is the taxiway/runway boundary; manned aircraft need ATC clearance to cross, and LAHSO operations put such a line mid-runway where two active runways intersect. Do-not-enter signs end discussion.

The BEACON operates sunset to sunrise - or during the DAY when visibility drops below VFR minimums, which is the exam's favorite version of the question. Colors: civil = alternating white/green; military = white-white-green; water = white/yellow; heliport = white-yellow-green.

The CHART SUPPLEMENT (renamed from the AFD) covers the US in 9 free regional volumes on a 56-day cycle: legend, airport listings, notices, associated data, airport diagrams. His worked decode of Prescott (KPRC): 7 miles north of town, UTC-7 (Arizona skips DST), field elevation 5,045 ft, beacon; traffic-pattern altitude 6,045 MSL (1,000 AGL) for light aircraft, 1,500 AGL for turbine/high-performance; runway 3/21 at 7,619 x 150 ft asphalt; right-traffic runways annotated, the rest left by silence.

NOTAMs carry what the 56-day cycle can't: NOTAM D (field/taxiway/lighting changes) and FDC NOTAMs (procedures, airspace, TFRs) are the testable pair; he mentions drone-specific ones informally as 'DRODAMs' (rare). ATIS: a per-airport recorded broadcast, refreshed hourly, lettered phonetically from Alpha each day - and it omits sky/visibility entirely when the ceiling beats 5,000 ft and visibility exceeds 5,000: 'good enough that you don't have to worry about it.'

Near-airport doctrine: outside controlled airspace no authorization is needed, but you must not interfere with any aircraft operation - know the pattern, stay out of short final. On the field itself, the badge-only SIDA area is real security (he reported violators as an airport employee).

The ACS hazard shelf: 'flying the wire' - power lines and their guy wires vanish against terrain; mitigate with a physical site walk plus sectional review. Lasers at aircraft get reported to ATC. Thermal plumes over industrial sites bring turbulence and electronics misbehavior. Birds go to ATC or bird NOTAMs. Cable-tethered balloons - nearly invisible, but charted on sectionals.