OO→SEA

JetBlue Airways cancels 4.6% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.

The early departures do better, though not dramatically: 89.4% on time for the 5am–8am window against 82.6% for 5pm–8pm. Worth taking if the schedule allows, not worth an extra connection. The 8pm–5am window is the busiest, with 5,823 flights scheduled in it.

August is the worst month at 77.8% on time, 12 points below October, the best at 89.5%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. September was the busiest month here, with 2,658 flights.

Extreme weather accounts for 19% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 3.1 times the usual weather exposure. The split is drawn from 255,536 reported delay minutes.

Cancellations are rare at 0.75%, below the national 1.89% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

Badly late arrivals are rare here: only 4.3% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.

28,580 flights sit behind these numbers, which is a large enough sample that the headline rate is not moving on noise. Where a sub-group falls below 30 flights the site shows a dash instead of a percentage.

Put together: take the 5am–8am departure, avoid August if the dates are flexible, and if two carriers are within a few dollars of each other, Envoy is the one with the record behind it. None of that guarantees an on-time arrival; it moves the odds by 32 points, which is the most any booking decision can do. 28,323 completed flights over 12 months sit behind that.