Best time to fly out of Nantucket Memorial (ACK)
The early-flight folk wisdom bends at Nantucket Memorial: the steadiest stretch was the 10am–12pm band at 82.1%, while 4–6pm departures managed 72%. 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 | – | – | – | – | – | – | – |
| 8–10am | – | – | – | – | – | – | – |
| 10am–12pm | 82 | 87 | 83 | 87 | 82 | 81 | 74 |
| 12–2pm | 82 | 80 | 83 | 81 | 80 | 81 | 77 |
| 2–4pm | 73 | 79 | 83 | 77 | 73 | 75 | 73 |
| 4–6pm | 71 | 78 | 74 | 73 | 73 | 75 | 62 |
| 6–8pm | – | – | – | – | – | – | – |
| 8–10pm | – | – | – | – | – | – | – |
| 10pm–12am | – | – | – | – | – | – | – |
The steadiest stretch at ACK was 10am–12pm — 82.1% of departures left on time across 1,032 flights. The weakest was 4–6pm at 72%.
The year at ACK
July was the hard month at ACK: 71.6% of departures left on time, across 1,411 flights. August was the easy one at 82.2%. 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 | Not enough flights to say | 0 |
| February | Not enough flights to say | 0 |
| March | Not enough flights to say | 0 |
| April | Not enough flights to say | 0 |
| May | 78.9% | 243 |
| June | 76.7% | 1,002 |
| July | 71.6% | 1,411 |
| August | 82.2% | 1,361 |
| September | 79.6% | 583 |
| October | 79.6% | 245 |
| November | Not enough flights to say | 0 |
| December | Not enough flights to say | 0 |
Airlines at ACK
Every airline with at least 100 departures from ACK, 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 |
|---|---|---|---|---|
| JetBlue Airways | 77% | 99 min | 4% | 2,822 |
| Republic Airways | 78.8% | 86 min | 6.8% | 1,889 |
What delays out of ACK were put down to
Airlines file a reason with every arrival running 15 minutes late or more. Across 1,190 flights that departed ACK and ran 15 minutes late or more, the delay minutes break down with 43.4% put down to late-arriving aircraft and 32.9% to air traffic & airport volume.
- Late-arriving aircraft 43.4%
- Airline operations 22.2%
- Air traffic & airport volume 32.9%
- Severe weather 1.3%
- Security 0.2%
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 ACK
Of 4,845 scheduled arrivals into ACK, 77.9% reached the gate less than 15 minutes behind schedule. Of the 895 arrivals that ran late, 48.2% 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 ACK
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.
ACK in one number
Nantucket Memorial (ACK)
Rank 209 of 363 US airports by departures. Steadiest stretch of the day: 10am–12pm. Hardest month: July.
Questions about ACK
- What is the best time of day to fly out of Nantucket Memorial?
- 10am–12pm. Departures in that band left on time 82.1% of the time across 1,032 flights, July 2023 through June 2026 — the best of the ten bands in the day. The 4–6pm band was the weakest at 72%.
- What is the worst month to fly out of ACK?
- July: 71.6% of the departures that flew left on time, with 1,411 scheduled. August was the other end of the year at 82.2%. Each figure pools three years of that calendar month.
- Which airline is most on time at ACK?
- Republic Airways — 78.8% of its 1,889 departures from ACK left on time. JetBlue Airways sat at the other end at 77% over 2,822 flights. Only airlines with at least 100 departures here are ranked.
- How often are flights cancelled at ACK?
- 5.1% 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.