Disruptions
Did the detector see the meltdowns coming, and how fast did each carrier recover?
The detector scores every carrier's day, and every day at the 30 busiest airports, against its own previous four weeks. Its threshold was chosen on 2015 to 2022 by the cost of a false alarm against a missed disruption, and graded on the reporting years against a table of known disruptions, each with a citation.
The known disruptions and when they were flagged
| Event | Onset | Window | Units | Flagged | First alert | Days after onset |
|---|---|---|---|---|---|---|
| Boeing 737 MAX grounding | 2019-03-13 | fitting | WN;AA;UA | yes | 2019-03-13 | 0 |
| COVID-19 collapse in air travel | 2020-03-15 | fitting | all | yes | 2020-03-17 | 2 |
| Winter Storm Uri in Texas | 2021-02-14 | fitting | DFW;DAL;IAH;HOU;AUS;SAT | yes | 2021-02-14 | 0 |
| Southwest scheduling crisis | 2022-12-21 | fitting | WN | yes | 2022-12-22 | 1 |
| Winter Storm Elliott | 2022-12-21 | fitting | all | yes | 2022-12-22 | 1 |
| FAA NOTAM system outage | 2023-01-11 | reporting | all | yes | 2023-01-11 | 0 |
| Alaska 1282 and the 737-9 grounding | 2024-01-06 | reporting | AS;UA | yes | 2024-01-06 | 0 |
| CrowdStrike outage and Delta's recovery | 2024-07-19 | reporting | DL | yes | 2024-07-19 | 0 |
| Hurricane Milton | 2024-10-08 | reporting | TPA;MCO;SRQ;RSW;PIE;SFB | yes | 2024-10-08 | 0 |
| Newark radar outages and flight caps | 2025-04-28 | reporting | EWR | yes | 2025-05-01 | 3 |
| Alaska Airlines IT outage and ground stop | 2025-10-23 | reporting | AS | yes | 2025-10-23 | 0 |
| FAA flight reductions during the federal shutdown | 2025-11-07 | reporting | all | yes | 2025-11-08 | 1 |
| January 2026 winter storm | 2026-01-24 | reporting | all | yes | 2026-01-24 | 0 |
Source: BTS Reporting Carrier On-Time Performance (real); model: detector; population: every scheduled flight, 2015 to 2026-07; as of 2026-10-01.
The operating point
A false alarm costs 1.0 and a missed disruption 50.0; the threshold with the least total cost on the fitting years was 29.0, inside the grid. On the reporting years it flagged 8 of 8 disruptions with 297 false alarm episodes.
The cost curve bottoms out at a threshold of 29.0
Total cost on the fitting years by alert threshold: false alarm episodes plus missed disruptions at their stated costs
Cost
Source: BTS Reporting Carrier On-Time Performance (real); model: detector; population: every scheduled flight, 2015 to 2026-07; as of 2026-10-01.
The two carrier meltdowns
Southwest Airlines took 9 days to get back to its peers and Delta Air Lines 5; across every alert episode, how fast a carrier recovers is a trait of the carrier
Daily cancellation rate of the carrier against other carriers at its ten busiest airports
Southwest Airlines, December 2022
Share of scheduled flights cancelled
- Southwest Airlines
- Other carriers at the same airports
Delta Air Lines, July 2024
Share of scheduled flights cancelled
- Delta Air Lines
- Other carriers at the same airports
Source: BTS Reporting Carrier On-Time Performance, model: the disruption detector, every scheduled flight, 2015 to 2026-07, as of 2026-10-01.
The alerts in the reporting years
| Unit | First day | Days | Peak score |
|---|---|---|---|
| airport TPA | 2024-09-26 | 2 | 166.7 |
| airport TPA | 2024-10-08 | 4 | 166.7 |
| airport MCO | 2024-10-09 | 3 | 166.3 |
| airport DCA | 2026-01-25 | 4 | 166.1 |
| airport IAH | 2025-01-21 | 2 | 166.1 |
| airport JFK | 2026-02-22 | 3 | 166.1 |
| airport DAL | 2023-01-30 | 4 | 164.2 |
| airport BWI | 2026-01-25 | 2 | 163.2 |
| airport DFW | 2026-01-24 | 5 | 158.6 |
| airport IAH | 2024-07-08 | 2 | 157.5 |
| airport PHL | 2026-01-25 | 4 | 155.7 |
| carrier OH | 2026-01-24 | 5 | 154.4 |
| carrier YX | 2026-01-24 | 4 | 151.1 |
| airport EWR | 2026-01-25 | 2 | 150.4 |
| airport CLT | 2026-01-24 | 5 | 149.6 |
| airport JFK | 2026-01-25 | 3 | 146.9 |
| airport DCA | 2025-01-06 | 2 | 146.7 |
| airport CLT | 2026-01-31 | 2 | 146.0 |
| airport DFW | 2025-01-09 | 2 | 142.1 |
| airport BNA | 2026-01-24 | 4 | 141.5 |
| airport DFW | 2023-01-30 | 4 | 140.2 |
| airport ATL | 2025-01-10 | 2 | 139.9 |
| carrier YX | 2026-02-22 | 3 | 133.7 |
| carrier B6 | 2026-01-25 | 3 | 130.6 |
| airport BOS | 2026-01-25 | 3 | 130.2 |
Source: BTS Reporting Carrier On-Time Performance (real); model: detector; population: every scheduled flight, 2015 to 2026-07; as of 2026-10-01.
Recovery by carrier
| Carrier | Alert episodes | Median days | Mean days | Longest |
|---|---|---|---|---|
| US Airways | 1 | 1.0 days | 1.0 days | 1 |
| Virgin America | 4 | 1.0 days | 1.2 days | 2 |
| Endeavor Air | 34 | 1.0 days | 1.7 days | 10 |
| Republic Airways | 42 | 1.0 days | 1.9 days | 11 |
| Envoy Air | 25 | 1.0 days | 2.0 days | 10 |
| Alaska Airlines | 9 | 1.0 days | 2.4 days | 10 |
| ExpressJet Airlines | 10 | 1.0 days | 2.5 days | 11 |
| American Airlines | 14 | 1.5 days | 2.6 days | 9 |
| JetBlue Airways | 34 | 2.0 days | 2.0 days | 6 |
| PSA Airlines | 23 | 2.0 days | 2.4 days | 11 |
| Delta Air Lines | 20 | 2.0 days | 2.5 days | 12 |
| United Airlines | 20 | 2.0 days | 2.7 days | 13 |
| Frontier Airlines | 13 | 2.0 days | 2.8 days | 14 |
| Southwest Airlines | 9 | 2.0 days | 2.9 days | 8 |
| Allegiant Air | 13 | 2.0 days | 3.2 days | 14 |
| SkyWest Airlines | 4 | 2.0 days | 3.8 days | 10 |
| Spirit Airlines | 16 | 2.5 days | 2.8 days | 7 |
| Horizon Air | 2 | 3.0 days | 3.0 days | 3 |
| Mesa Airlines | 4 | 4.0 days | 5.2 days | 12 |
| Hawaiian Airlines | 6 | 5.0 days | 6.5 days | 14 |
Source: BTS Reporting Carrier On-Time Performance (real); model: detector; population: every scheduled flight, 2015 to 2026-07; as of 2026-10-01.
What the ops director would push back on
The known events table is short, so a disruption that is real but not in the table counts as a false alarm, which overstates the false alarm rate. The peer control in the event studies is the other carriers at the same airports, who were hit by the same storm and carried some of the stranded carrier's passengers; the storm is differenced out, and the published excess is a floor.