Across 277,000 departures from American, Delta, and Southwest at TPA, a clear pattern hides in plain sight: the flight that leaves at 6 a.m. is almost always on time. The flight that leaves at 10 p.m. almost never is. The reason isn't weather. It isn't Tampa. It's a chain reaction that started somewhere else, hours earlier.
If you sort every TPA departure by its scheduled hour and look at the average delay, the line bends sharply upward through the day.
A 16x difference between the first wave of departures and the last.
The Bureau of Transportation Statistics splits delays into five categories. Two matter here:
Carrier delay = something broke at TPA today (a crew change, a maintenance issue, baggage, the airline's own ops).
Late Aircraft Arrival = the plane was already late when it landed at TPA, because its previous flight ran late.
Watch how the share shifts.
At 5 a.m., only 5.6% of delay minutes come from a late inbound plane. By 10 p.m., it's 78.7%. The carrier-caused share barely changes. It's the inherited delay that explodes.
A typical TPA narrow-body does four flights a day. The 6 a.m. plane overnighted at the gate — clean slate, no debt. By the third leg, every hiccup at every airport in between has stacked on top of it. The schedule has no slack to absorb 12 minutes lost in Dallas at noon, so the 9 p.m. departure inherits delay it had no part in creating.
Delays don't happen. They propagate.
In 2020 — the only year in this dataset when the system wasn't running near capacity — 76% of American Airlines flights left TPA early. So did 77% of Delta's. The average delay across all three carriers in 2020 was about one minute.
By 2024, that share had dropped to ~57%. The system isn't slower because the carriers got worse. It's slower because the schedule has no margin to absorb the inherited delays we just saw.
Share of AA flights leaving TPA early, 2020 vs 2024.
The story Tampa's delay data tells isn't about Tampa. It's about a national system running too tight to absorb its own friction. Every plane is one missed connection away from making every flight after it late, and the schedule pretends that won't happen.
The five a.m. flight isn't on time because it's better. It's on time because nothing has happened yet.