# Data Dictionary - US Flight Delays & On-Time Performance - monthly carrier × airport reliability panel, cleaned

**Units:** stated per column in the descriptions below (this is a relational table; columns mix units).

| column | type | description |
|---|---|---|
| `carrier` | str | Reporting airline code |
| `origin` | str | Origin airport (IATA) |
| `origin_city` | str | Origin city |
| `origin_state` | str | Origin US state |
| `year` | int | Year |
| `month` | int | Month (1-12) |
| `n_flights` | int | Scheduled flights |
| `pct_on_time` | float | % of operated flights arriving <15 min late |
| `pct_cancelled` | float | % of flights cancelled |
| `pct_diverted` | float | % of flights diverted |
| `avg_dep_delay` | float | Average departure delay (minutes) |
| `avg_arr_delay` | float | Average arrival delay (minutes) |
| `avg_carrier_delay` | float | Avg minutes of carrier-caused delay per operated flight |
| `avg_weather_delay` | float | Avg minutes of weather delay per operated flight |
| `avg_nas_delay` | float | Avg minutes of national-airspace delay per operated flight |
| `avg_security_delay` | float | Avg minutes of security delay per operated flight |
| `avg_late_aircraft_delay` | float | Avg minutes of late-aircraft delay per operated flight |

*Source: U.S. DOT, Bureau of Transportation Statistics - Reporting Carrier On-Time Performance (TranStats).*