G4

The spread between PVU and FLL is 25 points, wide enough that it should decide the booking. On a hundred trips that is 25 more arrivals inside the on-time window.

The 8pm–5am window is where this operation falls apart: 59.5% on time, against 90.9% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 2pm–5pm window is the busiest, with 26,967 flights scheduled in it.

June is the worst month at 68.8% on time, 14 points below September, the best at 83.0%. 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. July was the busiest month here, with 13,978 flights.

Across the week, Wednesday is the strongest day at 80.4% on time and Sunday the weakest at 70.5%. 10 points is a smaller lever than departure hour, but it is free.

Extreme weather accounts for 11% 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 1.8 times the usual weather exposure. The split is drawn from 2,856,407 reported delay minutes.

39% 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 2.86 million reported delay minutes here, that single category outweighs weather by 3 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.

Cancellations are rare at 0.65%, below the national 1.81% 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.

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.0% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.

127,163 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.