MDWOCT

Book the early departure. Flights leaving between 5am–8am arrive on time 90.1% of the time, against 70.4% for the evening window. That is 20 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 1,574 flights scheduled in it.

Across the week, Wednesday is the strongest day at 87.9% on time and Sunday the weakest at 70.3%. 18 points is a smaller lever than departure hour, but it is free.

42% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 58,000 reported delay minutes here, that single category outweighs weather by 42 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 58,282 reported delay minutes.

Cancellations are rare at 0.17%, below the national 0.53% 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 6.3% 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.