Methodology & data quality
Every number should survive a second look.
Arrival Atlas is historical descriptive analytics. It summarizes official flight records; it does not forecast, predict, or guarantee the outcome of a future trip.
Source of record
Official BTS on-time performance data
The source is the US Bureau of Transportation Statistics Reporting Carrier On-Time Performance table. Arrival Atlas downloads official pre-zipped monthly files and preserves each URL, ETag, source modification date, download timestamp, byte count, and SHA-256 checksum in a local lineage manifest.
Metric dictionary
Formulas and denominators
| Metric | Formula | Denominator / population |
|---|---|---|
| Scheduled flights | Count of reporting-carrier flight records scheduled for the selected cohort. | All selected records |
| Operated flights | Scheduled flights that were not cancelled. Diverted flights are operated flights. | Scheduled flights |
| On-time arrival rate | Observed arrivals with ArrDelay < 15 minutes ÷ observed arrivals. | Non-cancelled, non-diverted flights with ArrDelay |
| Cancellation rate | Cancelled flights ÷ scheduled flights. | Scheduled flights |
| Diversion rate | Diverted flights ÷ scheduled flights. | Scheduled flights |
| Median / P75 / P90 delay | Exact continuous quantiles of BTS ArrDelay within the displayed cohort. | Non-cancelled, non-diverted flights with ArrDelay |
| 30+ / 60+ minutes late | Observed arrivals at or above the threshold ÷ observed arrivals. | Non-cancelled, non-diverted flights with ArrDelay |
| Delay-cause distribution | Positive reported minutes for carrier, weather, NAS, security, and late-aircraft causes ÷ total positive reported cause minutes. | Flights where BTS reports attributable cause minutes |
Reproducible pipeline
Raw → cleaned → application-ready
Raw monthly ZIPs
Immutable BTS downloads stay outside Git. A manifest records origin, checksum, size, ETag, and extraction date.
Cleaned Parquet
Columns are typed, exact flight keys are deduplicated, identifiers are retained, and invalid durations are flagged.
Origin partitions
DuckDB calculates exact cohort metrics, then emits compact Zstandard Parquet files used by the web application.
Inclusion and comparison rules
- • US domestic scheduled flights reported in the BTS source table.
- • Calendar month uses the scheduled flight month.
- • Departure band uses scheduled local origin time.
- • Carrier identity retains stable DOT ID plus the historical reporting code.
- • Rankings apply only inside one route/month/time cohort.
- • A minimum of 100 observed arrivals is required to receive a rank.
- • Current-period comparisons use the same calendar month one year earlier.
Exclusions and known limitations
- • Cancelled flights never receive a zero-minute delay.
- • Cancelled and diverted flights are excluded from delay distributions.
- • Missing cause minutes stay missing; they are not assigned to “other.”
- • Codes and ownership can change; names are display labels, not stable keys.
- • Reporting-carrier data may differ from the marketing airline a traveler sees.
- • The dataset excludes unreported, international, and non-scheduled operations.
- • Weather and operational conditions for a future trip may be materially different.
Publication gate