Airports & Carriers¶

The airfield model (AP*): a small registry of airports and carriers, the takeoff/landing classification that drives the player and AI ground state machines, parking-spot assignment, the ILS-style approach path, free-flight teleport, and the carrier-deck attachment that makes a parked aircraft ride a moving ship. This is the behaviour behind the _STRIPProc (runway) and _CARRIERProc (carrier) object classes that objects.md names.

Provenance: Ghidra static analysis of the game executable with FA.SMS symbols applied; recorded in the symbol database and applied to the Ghidra project. Progress: reconstruction matrix. Markers follow spec-authoring.md: confirmed · inferred · unknown.

The registry (#493)¶

APInit/APAdd/APDelete/APFind maintain up to 0x28 AIRPORT records (0x134 bytes each, at _airports), keyed on the backing object id (+0xE6). The airport object carries the runway/deck geometry the rest of the system reads: touchdown point (+0xAA), runway heading (+0xDA), glideslope (+0x10D), and the parking-spot array (+0x111, count at +0xE0). APNearest is the core query — nearest airport to a point, filtered by side (friendly-only for AI recovery), the landable class flag (object type +9 bit 0x8000), and optionally a valid landing type or a live-and-owned test. confirmed

Takeoff & landing classification¶

APTakeoffType and APLandingType map a plane + airport pair to a state the flight state machine enters, reading the plane's capability bits (class +0xBA: VTOL 0x8, catapult 0x2, carrier 0x20) against the airport's facility bytes (+0xE8..+0xEC): confirmed

result	takeoff	landing
vertical (VTOL)	`10`	`0x18`
catapult launch	`7`	—
carrier deck	`0xD` (taxi)	`0x18`
arrested	—	`0x16`
conventional runway	`0x11`	`0x17`

These are the exact states PlayerUpdateState (input.md § ServicePlayer, #492) and the AI recovery logic transition into. APOnCatapult is the "am I on the cat spot" test that gates the catapult launch. confirmed

Parking & traffic¶

Each airport owns a fixed set of parking spots; APAssignPark/APGetPark/APUnassignPark/ APClearParks hand them out to _curId and release them (a plane holds at most one spot, across all airports). APStripFree sequences runway traffic — it asks every other plane controlled by the same airport (via that plane's class proc call 8) whether the strip is clear before a takeoff or landing roll begins. confirmed

Approach & teleport¶

APApproachPath computes the glideslope steering to the home field: the cross-track and vertical offsets from the touchdown point, rotated into the runway heading, plus a range-scaled throttle and gear cue — the numbers an ILS needle or an AI final-approach controller consumes. APHomeAirport selects the destination (the last flight-plan waypoint if one exists, else the nearest landable friendly field). APTeleport is the free-flight convenience jump to the nearest airport — on the runway (0), short final with the hook down (1), or airborne at 10k/40k (2/3) — each re-seeding the flight model via FMInitPlane. confirmed

Carrier decks¶

A carrier is an airport that moves, so a parked aircraft must ride it. APCheckCarrier (called each frame from ServicePlayer) tests whether the player is stopped on a carrier deck (APOnDeck — a downward collision probe inside the ship's bounding box) and, if so, attaches it via APAddToCarrier: APSetOffset records the aircraft's position relative to the deck (rotated offset + heading delta) in an OBJ_ON_CARRIER slot (occupancy table at 0x58E870), so each frame the aircraft is carried with the ship. APRemoveFromCarrier detaches on rollout, and APObjOnShip answers "is object N currently riding a carrier, and which one". confirmed

Airports: the AP registry keys airports by object id; APNearest + APTakeoff/LandingType drive the ground state machine, APApproachPath the final, and APCheckCarrier attaches a parked aircraft to a moving carrier deck.

Functions¶

Full record: db/symbols/airports.csv.

VA	Symbol	Role
`0x4BA8E0`	`APNearest`	nearest airport to a point, side/landable filtered
`0x4BAA10`	`APTakeoffType`	classify takeoff (VTOL/catapult/deck/runway)
`0x4BAAC0`	`APLandingType`	classify landing (vertical/arrested/runway)
`0x4BAC70`	`APStripFree`	is the runway clear of other AI traffic
`0x4BE6A0`	`APApproachPath`	glideslope steering to the home field
`0x4BE8E0`	`APTeleport`	free-flight jump to the nearest airport
`0x4BEB90`	`APCheckCarrier`	attach/detach a parked aircraft to a carrier deck
`0x481150`	`AtFriendlyAP`	on the ground near the nearest airport
`0x48F6A0`	`APCommentProc`	tower/LSO chatter (takeoff/cat/ball/wind/welcome calls)

Open Questions¶

1. The AIRPORT and OBJ_ON_CARRIER record layouts¶

The 0x134-byte AIRPORT record and the 0x18-byte OBJ_ON_CARRIER slot are read field-by-field here (touchdown +0xAA, heading +0xDA, glideslope +0x10D, parking array +0x111), but neither is a declared struct in db/types/. A full layout — and confirming which fields come from the .NT/.OT object-type files versus runtime — would let the objects.md _STRIPProc/_CARRIERProc rows point at a struct.

Status: open — re-static (map the AIRPORT / OBJ_ON_CARRIER records into db/types/).

objects.md — the _STRIPProc / _CARRIERProc object classes this drives.
input.md — PlayerUpdateState / ServicePlayer consume the takeoff/landing states and call APCheckCarrier.
campaign.md — APTeleport and APHomeAirport serve the free-flight and recovery flows.
physics.md — FMInitPlane, which APTeleport re-seeds.