> ## Documentation Index > Fetch the complete documentation index at: https://docs.flightportrait.com/llms.txt > Use this file to discover all available pages before exploring further. # Open questions > Callsigns whose route observation settled at one end only, most-seen first. Each row says which end is missing, which is known, where the aircraft was last heard, and how far its rotation says the other end is. Answers go to the contribution door, not this API. Rate: 300 per 600 s (bucket `gaps`). Cache: 10 min edge. ## OpenAPI ````yaml /openapi.json get /v1/gaps openapi: 3.1.0 info: title: FlightPortrait network API description: >- Open data from the FlightPortrait receiver network. No API key. **Stability.** Operations marked `x-stability: stable` only ever gain fields; names and types are frozen. Operations marked `x-stability: map` exist for the first-party map and can change with it. **Field dialects.** `/v1/aircraft` and `/v2/point` pass readsb's wire fields through unchanged (`hex`, `t`, `r`, `gs`, ...) so ecosystem tooling works as-is. Every other resource uses full words: `reg`, `type`, `org`, `dst`. Airport codes in history resources are IATA; `/v1/airports/{code}` accepts IATA or ICAO. Event times are unix seconds UTC; registry timestamps are ISO 8601 UTC; board and schedule times are HH:MM in the origin airport's local time. **Data honesty.** History is observation, never an official registry. Gaps mean the network's sources did not hear it, nothing more. Responses carry `coverage: "observed"` as a reminder. The one exception is the airport departures board, whose rows may be inferred from published timetables — each board row carries its own `source` (observed / published / both); a published row is not a receiver observation. Likewise a flight's `route_source`: `observed` when both ends were seen, `observed+catalog` when the community supplied the end coverage never reached, `catalog` when it supplied both. Catalog answers are checked against observation and reviewed before they are served, and observation outranks them whenever it speaks. This API is read-only; answers go to the contribution door at contribute.flightportrait.com. **Errors.** Every non-200 body is `{"error": , "detail": }` with `Cache-Control: no-store`. 404 `not_found` / `not_observed`, 422 `invalid_request`, 429 `rate_limited` (with `Retry-After` and `RateLimit-*` headers), 503 `stale_snapshot` (live snapshot older than 60 s) or `artifact_unavailable` (a history artifact is not loaded). **Rate limits.** Per IP, per bucket, over a 600 second window; each operation notes its bucket and default limit. 429 means wait for `Retry-After` seconds. Data is ODbL 1.0. Credit "FlightPortrait network feeders" and link the credits page, which lists every source the data draws on and the credit each one asks for; republishing carries them too. Credits: https://flightportrait.com/network/credits.html Terms: https://flightportrait.com/network/terms version: 1.0.0 servers: - url: https://data.flightportrait.com security: [] tags: - name: Live description: What the network hears now. - name: History description: Observed airframes, flights, airports. - name: Stations description: Feeder roster. - name: Reference description: Airlines, alliances, types. - name: Contributions description: What observation could not settle, and the community answers to it. - name: Meta description: Index and health. paths: /v1/gaps: get: tags: - Contributions summary: Open questions description: >- Callsigns whose route observation settled at one end only, most-seen first. Each row says which end is missing, which is known, where the aircraft was last heard, and how far its rotation says the other end is. Answers go to the contribution door, not this API. Rate: 300 per 600 s (bucket `gaps`). Cache: 10 min edge. operationId: gaps parameters: - name: airline in: query required: false schema: anyOf: - type: string minLength: 2 maxLength: 3 - type: 'null' description: ICAO airline prefix. title: Airline description: ICAO airline prefix. - name: side in: query required: false schema: anyOf: - type: string pattern: ^(origin|dest)$ - type: 'null' title: Side - name: limit in: query required: false schema: type: integer maximum: 200 minimum: 1 default: 50 title: Limit - name: offset in: query required: false schema: type: integer minimum: 0 default: 0 title: Offset responses: '200': description: OK content: application/json: schema: type: object properties: total: type: integer description: Rows matching the filters. offset: type: integer gaps: type: array items: type: object properties: callsign: type: string side: type: string description: 'The missing end: origin or dest.' known: type: string description: The settled end, IATA. hint: type: - string - 'null' description: >- The missing end's leading code when observation saw it too rarely to settle it. chain: description: >- Every known stop in order when the callsign is a chain with one end unseen; the missing end goes before or after it. Null for a single leg. oneOf: - type: array items: type: string - type: 'null' type: type: - string - 'null' description: Dominant aircraft type on the leg. n_recent: type: integer description: Sightings in the last 90 days. last_seen: type: string description: Last date observed, YYYY-MM-DD. last_heard: description: >- Where the most recent truncated leg was last heard, with its track in degrees true. Null when unknown. oneOf: - type: object properties: lat: type: number lon: type: number track: type: - integer - 'null' - type: 'null' rotation_km: type: - integer - 'null' description: >- How far the missing end is, from the time the airframe takes to come back. Null until a few rotations were seen. suggested: type: array items: type: string description: >- Airports the evidence allows for the missing end, best first: at the rotation's distance, within the type's range, along the last heard track, ranked by how much the airline is seen flying there. Empty until the rotation is known. coverage: type: string description: >- Always "observed": evidence from our receivers and open trace archives, never a published schedule or registry. const: observed required: - total - offset - gaps - coverage example: total: 1 offset: 0 gaps: - callsign: SIA842 side: dest known: SIN type: B78X n_recent: 13 last_seen: '2026-09-06' last_heard: lat: 12.41 lon: 106.92 track: 21 rotation_km: 3150 suggested: - TFU - CTU coverage: observed '422': description: Validation Error content: application/json: schema: $ref: '#/components/schemas/HTTPValidationError' '429': description: >- Rate limited. Wait Retry-After seconds. Headers: Retry-After, RateLimit-Limit, RateLimit-Remaining, RateLimit-Reset. content: application/json: schema: properties: error: type: string description: >- Machine code: not_found, not_observed, invalid_request, rate_limited, stale_snapshot, artifact_unavailable, upstream_unavailable. detail: type: string description: Human-readable explanation. type: object required: - error - detail example: error: rate_limited detail: slow down '503': description: >- Live snapshot older than 60 seconds (stale_snapshot) or a required history artifact is not loaded (artifact_unavailable). Retry-After is set. content: application/json: schema: properties: error: type: string description: >- Machine code: not_found, not_observed, invalid_request, rate_limited, stale_snapshot, artifact_unavailable, upstream_unavailable. detail: type: string description: Human-readable explanation. type: object required: - error - detail components: schemas: HTTPValidationError: properties: detail: items: $ref: '#/components/schemas/ValidationError' type: array title: Detail type: object title: HTTPValidationError ValidationError: properties: loc: items: anyOf: - type: string - type: integer type: array title: Location msg: type: string title: Message type: type: string title: Error Type input: title: Input ctx: type: object title: Context type: object required: - loc - msg - type title: ValidationError ````