Best time to fly out of Antonio B. Won Pat (GUM)
The early-flight folk wisdom holds up at Antonio B. Won Pat: departures in the 8–10am band left on time 95% of the time, against 84.9% in the 6–8am band. These are historical odds, not forecasts. The records say what happened on this schedule over three years; they know nothing about tomorrow’s thunderstorm.
Data through June 2026 · Bureau of Transportation Statistics
On-time rate by hour and day
On this page, “on time” means a departure that pushed back less than 15 minutes behind its scheduled time — the Bureau of Transportation Statistics definition, and the one airlines are held to.
| Departure time | Mon | Tue | Wed | Thu | Fri | Sat | Sun |
|---|---|---|---|---|---|---|---|
| Before 6am | – | – | – | – | – | – | – |
| 6–8am | 91 | 97 | 68 | 93 | 89 | 65 | 92 |
| 8–10am | 96 | 99 | 90 | 94 | 98 | 91 | 97 |
| 10am–12pm | – | – | – | – | – | – | – |
| 12–2pm | – | – | – | – | – | – | – |
| 2–4pm | – | – | – | – | – | – | – |
| 4–6pm | – | – | – | – | – | – | – |
| 6–8pm | – | – | – | – | – | – | – |
| 8–10pm | – | – | – | – | – | – | – |
| 10pm–12am | – | – | – | – | – | – | – |
The steadiest stretch at GUM was 8–10am — 95% of departures left on time across 1,085 flights. The weakest was 6–8am at 84.9%.
The year at GUM
February was the hard month at GUM: 87% of departures left on time, across 170 flights. October was the easy one at 94.6%. Each month pools three years of that month, so a single bad week does not decide it.
| Month | Share departures that left on time | Flights |
|---|---|---|
| January | 88.2% | 186 |
| February | 87% | 170 |
| March | 90.4% | 188 |
| April | 89.4% | 180 |
| May | 89.7% | 186 |
| June | 89.9% | 180 |
| July | 87.2% | 195 |
| August | 89.7% | 195 |
| September | 93.8% | 181 |
| October | 94.6% | 186 |
| November | 89.9% | 180 |
| December | 90.3% | 186 |
Airlines at GUM
Every airline with at least 100 departures from GUM, busiest first. These are that airline’s departures from this airport only — its record across the country sits on its own page.
| Airline | Left on time | Typical delay | Cancelled | Departures |
|---|---|---|---|---|
| United Airlines | 90% | 56 min | 1.1% | 2,213 |
What delays out of GUM were put down to
Airlines file a reason with every arrival running 15 minutes late or more. Across 144 flights that departed GUM and ran 15 minutes late or more, the delay minutes break down with 51.8% put down to airline operations and 36.5% to late-arriving aircraft.
- Late-arriving aircraft 36.5%
- Airline operations 51.8%
- Air traffic & airport volume 10.1%
- Severe weather 1.6%
- Security 0%
Late-arriving aircraft is the knock-on category: the plane came in late, so it went out late again. It is why a 7am problem in Newark is still a problem in Denver at dinnertime, and why it is usually the biggest slice on the bar.
If you are connecting through GUM
Of 2,213 scheduled arrivals into GUM, 86.9% reached the gate less than 15 minutes behind schedule. Of the 272 arrivals that ran late, 69.5% were no more than 45 minutes behind — which is the difference between a tight connection and a new boarding pass.
Work out a specific layover — pick the airport and the minutes you have, and the tool reads the same arrival records back as a share.
Busiest routes out of GUM
Ranked by flights, with the share that arrived on time at the far end. Where a route carries enough flights for a page of its own the chip goes there; otherwise it goes to the destination airport.
GUM in one number
Antonio B. Won Pat (GUM)
Rank 256 of 363 US airports by departures. Steadiest stretch of the day: 8–10am. Hardest month: February.
Questions about GUM
- What is the best time of day to fly out of Antonio B. Won Pat?
- 8–10am. Departures in that band left on time 95% of the time across 1,085 flights, July 2023 through June 2026 — the best of the ten bands in the day. The 6–8am band was the weakest at 84.9%.
- What is the worst month to fly out of GUM?
- February: 87% of the departures that flew left on time, with 170 scheduled. October was the other end of the year at 94.6%. Each figure pools three years of that calendar month.
- How often are flights cancelled at GUM?
- 1.1% of scheduled departures were cancelled over July 2023 through June 2026. Cancellations are counted against everything scheduled, not against everything that flew — a rate that looks small still adds up to real people in a rebooking line.