Last updated 14 October 2026. Use of the API and the connector is under the API terms.
What it answers
Give the flight number of a direct flight, or the two flight numbers of a connection, and the date of the first flight. The answer is the grade the site's connection check gives those flights, A to F, from last year's US flight records for that weekday and season, with how often it ended in a missed connection and the card's own notes. It is worked out by the same engine, from the same data, as the cards on the site. Times are from the past year's schedules; check the airline for the current timetable. Grades are estimates and carry no guarantee. Always check your airline's minimum connection time.
A trip with more than one connection: ask once for each connection. If a flight didn't fly within 45 days of that date last year, the answer still grades it, as the site's connection check does, labelled “Didn't run around this date last year: limited data, may not operate.” (with offseason: true). If the flights have too few days in our records to grade at all, the answer says there is not enough history and gives no grade.
The API
GET https://getgatecast.com/api/score?date=2026-11-03&flights=UA2040,UA767&route=BOS-ORD-DEN
flights: one flight number (a direct flight) or two (a connection, in flying order), the airline code and the number.date: the first flight's departure date, YYYY-MM-DD.route(recommended): the airports in flying order, e.g. BOS-ORD-DEN for a connection or BOS-ORD for a direct flight.inbound_delay(optional, connections only): how late the first flight is now, in minutes (negative = early). The answer then addsp_miss_nowandp_miss_now_text, the chance of missing the connection on last year's days the first flight landed about that late (days the first flight was cancelled or diverted are not in this figure; the overall chance counts them),now_basis(which days, and how many), andnext_backup, the next later flight on the same airline (or its regional partner) from last year's timetable. With too few such days it gives no figure and says so. Without it, the answer is unchanged.
A flight number can fly more than one route. If it flew more than one route around that date last year and no airports are given, the answer asks for them and gives no grade; if the airports don't match our records for that number, the answer says what we found and gives no grade.
Send only these fields: never names, booking references or other personal data.
Every answer carries disclaimer, a dated source line (data_period, bundle_date), the times line, attribution and terms, and the header Link: <https://getgatecast.com/terms/#api>; rel="terms-of-service". A graded answer has its grade, grade_cost (the grade from lateness alone), p_miss, the card's label and why lines, modelled, basis (and basis_short, the same in 60 characters or fewer for short replies); a direct flight also has counts: days it was scheduled among the days graded, of which flown and cancelled (cancelled or diverted), late60 (flown days arriving 60 minutes or more late) and the basis of those days and the flights. If you show a grade to anyone, show the disclaimer and the source line with it, as the terms say.
The AI-assistant connector
Add https://getgatecast.com/mcp as a custom connector (Model Context Protocol) in an assistant that supports one. It has one read-only tool, grade_us_flight_itinerary, which asks the same question as the API and gets the same answer. The connector page has the details for assistant users. Nothing is booked, stored or sent anywhere else.
Limits
- 10 answers a minute for each caller; more are refused with status 429.
- There is no daily limit beyond that. Each answer is kept for up to 6 hours, so the same question in that time gets the same stored answer.
- US domestic flights only, one itinerary at a time.
For bulk scoring, files or a commercial licence, email hello@getgatecast.com.
Errors
400 a field is missing or wrong; 404 a flight number is not in our records; 422 the two flights don't connect in our records; 429 over the limit; 503 the flight data could not be loaded. Each error still carries the disclaimer, the source line and the terms link.