What T-100 is and who files it
T-100 is the monthly traffic and capacity filing that the US Department of Transportation (DOT) requires from airlines. The Bureau of Transportation Statistics (BTS) describes the T-100 data bank as domestic and international market and segment data without carrier financial information, with monthly data from 1990.
- Large certificated US carriers: File Form 41 Schedule T-100 every month under 14 CFR Part 241 (Sec. 19-1).
- Commuter and small certificated US carriers: File Schedule T-100 monthly under 14 CFR 298.61.
- Foreign carriers: Each foreign air carrier that DOT authorizes to fly passengers or cargo to or from the United States files Schedule T-100(f) under 14 CFR Part 217.
Under 14 CFR Part 241 (Sec. 19-3(c)) and 14 CFR 217.3(d), T-100 and T-100(f) reports are due within 30 days after the end of each reporting month. On TranStats, BTS publishes a U.S. Carriers database and an All Carriers database, each with Domestic Market, Domestic Segment, International Market, International Segment, and combined Market and Segment tables.
Segment data versus market data
T-100 Segment and T-100 Market count the same flights in two ways. 14 CFR Part 217 (Appendix A) gives the core example: a flight routed A-B-C-D produces three nonstop segment records (A-B, B-C, C-D) and six on-flight market records (A-B, A-C, A-D, B-C, B-D, C-D).
Under 14 CFR Part 241 (Sec. 19-2(d)), segment data are summarized by aircraft type, within service class, within each airport pair. Market records are summarized by service class within each airport pair, without regard to aircraft type.
"Revenue passengers transported" (code 130, a segment field) counts everyone on board over one flight stage, including passengers already on board from an earlier stage. "Revenue passengers enplaned" (code 110, a market field) is an unduplicated count of passengers boarding a flight for the first time.
The main fields and service classes
14 CFR Part 241 sets out the main T-100 items for US carriers, in Sec. 19-5 (reported and DOT-computed items) and Sec. 19-4 (service classes):
- Segment side: Aircraft type, departures performed (510) and scheduled (520), available seats (310), available payload (270), passengers transported (130), freight (237) and mail (239) transported, airborne hours (610) and ramp-to-ramp hours (630).
- Market side: Passengers (110), freight (217) and mail (219) enplaned.
- Computed by DOT: Great-circle distance in statute miles (501), plus revenue passenger-miles, available seat-miles and ton-miles, counting 200 pounds per passenger, baggage included, for passenger ton-miles.
- Service class (Sec. 19-4, US carriers): F (scheduled passenger/cargo), G (scheduled all-cargo), L (nonscheduled civilian passenger/cargo), P (nonscheduled civilian cargo), N and R (nonscheduled military).
Under 14 CFR 217.5, foreign carriers report fewer items, with freight and payload in kilograms and no mail or departures-scheduled item. The published T-100 Segment (All Carriers) table gives payload, freight and mail in pounds and air time and ramp-to-ramp time in minutes.
Release timing and revisions
As of October 2026, the TranStats download pages list July 2026 as the latest month for T-100 Domestic Segment and Domestic Market (U.S. Carriers) and for T-100 Segment and Market (All Carriers). The TranStats release log shows July 2026 data added to the domestic and international tables on October 9, 2026, and June 2026 data on September 14, 2026, roughly a 10-week lag for both.
Each release can revise earlier months. The October 9, 2026 release also updated December 2023 through April 2026 in T-100 Domestic Segment (All Carriers).
Written descriptions do not all match the TranStats release log. The TranStats database description says international data come out three months after domestic data, and a BTS Restricted Data page dated December 4, 2024 describes a six-month restriction on international data. The current 14 CFR Part 241 Sec. 19-6(b), amended in January 2023, makes detailed international data public once DOT determines the database is complete.
Lookup tables for joining the data
TranStats data download as comma-delimited (CSV) files, with a separate lookup table for each coded field, from carrier and airport IDs to aircraft type, distance group, service class and data source. Some codes are arbitrary, so the lookup table is needed to read them. Very large tables cannot be downloaded with all months or all fields selected at once.
- UniqueCarrier: The two-letter Carrier field holds the commonly used IATA code, which is not always unique; BTS advises UniqueCarrier for analysis across years.
- AirlineID: Identifies an airline regardless of code or name changes.
- AirportID: Used because an airport can change its code and codes can be reused.
- CityMarketID: Groups airports that serve the same city market.
- DataSource: DU, DF, IU and IF separate domestic and international data from US and foreign carriers.
Common ways the data is misread
- Adding up segment passengers: Passengers transported counts a through passenger on every stage of a multi-stop flight; passengers enplaned (code 110) is the unduplicated count.
- Reading service class as cabin: Class F combines first class, coach and mixed passenger/cargo service, so T-100 does not count business-class passengers separately.
- Reading aircraft codes as model numbers: T-100 aircraft type codes are numbers assigned by DOT. In the BTS lookup table, as of October 2026, code 637 is the Boeing 777-300/300ER and code 777 is the Bombardier Challenger 850.
- Crediting a codeshare to the marketing airline: Under 14 CFR Part 241 (Sec. 19-2(e)) and 14 CFR 298.61, code-shares, blocked-space deals and wet leases are reported by the carrier in operational control of the aircraft, meaning the carrier whose flight crews operate it, not by the marketing carrier.
- Treating a foreign carrier's gateway as the origin: On flights through a foreign carrier's homeland, US traffic to or from third-country points is combined with the homeland gateway airport, and the actual point is not disclosed.
- Treating a download as final: BTS revises earlier T-100 months when adding a new one.
What T-100 does not cover
- Financial data: The T-100 data bank does not include carrier financial information.
- Ticket data: T-100 has no ticket-value fields. BTS publishes ticket data in the Airline Origin and Destination Survey (DB1B), a quarterly 10% ticket sample covering 1993 to 2025, and from July 2025 in DB1C, a monthly 40% sample.
- Flight numbers: Neither segment nor market records are kept by flight number.
- Foreign-to-foreign flights: The TranStats T-100 tables leave out flights with both ends in a foreign country.
- Military flights: Service classes N and R are excluded from the public domestic data.
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