> ## 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. # One question > The open question for one callsign, the answers on file, and the catalog answer in force if there is one. 404 when observation has no question for it. Rate: 300 per 600 s (bucket `gaps`). Cache: 10 min edge. ## OpenAPI ````yaml /openapi.json get /v1/gaps/{callsign} 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/{callsign}: get: tags: - Contributions summary: One question description: >- The open question for one callsign, the answers on file, and the catalog answer in force if there is one. 404 when observation has no question for it. Rate: 300 per 600 s (bucket `gaps`). Cache: 10 min edge. operationId: gap parameters: - name: callsign in: path required: true schema: type: string description: Callsign or flight ident, 2-12 alphanumerics. title: Callsign description: Callsign or flight ident, 2-12 alphanumerics. responses: '200': description: OK content: application/json: schema: 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. catalog: description: >- The community answer in force, if any: the whole route, IATA. oneOf: - type: object properties: route: type: array items: type: string valid_from: type: string - type: 'null' answers: type: array items: type: object properties: origin: type: string dest: type: string status: type: string description: pending or approved. verdict: type: - string - 'null' description: >- corroborated, contradicted, unverified, or contested. description: Answers on file, oldest first, rejected ones left out. example: 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 answers: [] '404': description: Not found or not observed. 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 '422': description: Malformed input. 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 '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 ````