Decatur, IL

What the Data Says About DEC

Decatur, IL in Decatur, Illinois handled 9,084 flights in the Bureau of Transportation Statistics dataset between 2020 and 2025, posting a 84.5% on-time departure rate. Of those flights, 1,405 experienced delays, 154 were cancelled, and 8 were diverted. The cancellation rate works out to 1.70%, the diversion rate to 0.09%, and the average delay when departures run late is 127.5 minutes. These figures are the baseline for comparing DEC against other airports in the same state and nationally.

Breaking down what drives delays at DEC, Carrier leads the pack. Carrier accounts for 48.9% of total delay minutes, followed by Late Aircraft at 39.8% and NAS (National Aviation System) at 6.1%. Weather contributes 5.1% of delay minutes at this airport, while security holds the smallest share at 0.0%. Travelers often overestimate the weather share; the BTS categorization shows late-arriving aircraft and carrier operations as the larger contributors.

Seasonally, October runs the cleanest at DEC with a 94.9% on-time rate, while December is the roughest at 90.6% — a 4-point swing between best and worst month. Volume peaks in April, when average flights hit 141. The busiest route from DEC is to DEC (Decatur), with 3,614 flights at a 82.6% on-time rate. Combine these numbers — 84.5% on-time, 127.5-minute average delay, 1.70% cancellation rate — and you have a concrete picture of departure reliability at Decatur, IL.