Carrier route record
DLPHX→BOS
Delta Air Lines · Phoenix to Boston
- Flights
- 429
- Period
- September 2025 to August 2026
- Share of route
- 21%
- Carriers
- 3
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on PHX to BOS lands a B, level with the national rate of 77.3%. About one flight in four arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That rests on 429 flights, with a median arrival 5 minutes early.
The US average over the same twelve months is 77.3%, so there is little to separate Delta on PHX to BOS from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
76.6%
Arrivals under 15 minutes late, of 419 completed flights
Avg delay
84 min
Across delayed arrivals only, not all flights
Cancelled
2.33%
National rate is 1.89%
Whole route
75.7%
Every carrier on PHX to BOS, 2,010 flights
These figures cover 429 flights between September 2025 and August 2026. Beyond the headline rate, 8.8% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Delta against every carrier on PHX to BOS
Delta flew 429 of the 2,010 flights on PHX to BOS, about 21% of it. Its 76.6% on time is about level with the route as a whole at 75.7%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Delta at 76.6% to JetBlue at 72.2%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines (this page) | 429 | 76.6% | 84 min | 2.33% | B |
| American Airlines | 1,308 | 76.1% | 69 min | 1.61% | B |
| JetBlue Airwaysthin sample | 273 | 72.2% | 80 min | 2.20% | C |
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Departure window
When Delta runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 14 points, against half a point between the best and worst carrier.
- 5am–8am—
- 8am–11am—
- 11am–2pm197 flights68.9%
- 2pm–5pm16 flights—
- 5pm–8pm—
- 8pm–5am216 flights83.0%
Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.
The weak window here is the middle of the day, not the evening: 11am–2pm runs 68.9% on time against 83.0% for 8pm–5am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 8pm–5am window is the busiest, with 216 flights scheduled in it.
Across the year
Delta on PHX to BOS through the year
May is the best month on the calendar at 94.3% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. March was the busiest month here, with 49 flights.
Across the week, Monday is the strongest day at 83.1% on time and Sunday the weakest at 67.2%, a spread of 16 points.
Arrival by arrival
How late Delta on PHX to BOS runs when it is late
Delta on PHX to BOS often beats the schedule: 122 of 419 completed flights, 29%, arrived 15 minutes or more early. The 98 late arrivals split 33 under half an hour, 28 between 30 and 60 minutes, and 37 an hour or more.
- 15+ min early122 flights29.1%
- Within 15 min199 flights47.5%
- 15–29 min late33 flights7.9%
- 30–59 min late28 flights6.7%
- 1–2 hours late24 flights5.7%
- 2+ hours late13 flights3.1%
Scale runs 0% to 100%.
Share of 419 completed flights by arrival against schedule.
19 of 90 late departures made up the time and arrived on time, 21% of them. In the other direction, 27 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at BOS.
The worst days
Worst days for Delta on PHX to BOS
The latest arrival of the period was on 12 June 2026, 12 hours 13 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on four of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 12 June 2026 | 12 hours 13 minutes | Carrier |
| 18 September 2025 | 12 hours 12 minutes | Carrier |
| 6 June 2026 | 10 hours 56 minutes | Carrier |
| 23 February 2026 | 6 hours 20 minutes | Extreme weather |
| 15 November 2025 | 5 hours 12 minutes | Carrier |
Delay causes
Why Delta runs late on this route
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 8,180 reported delay minutes.
- 42%Carrier
- 27%National Airspace System
- 24%Late-arriving aircraft
- 7%Extreme weather
The largest share of delay minutes, 42%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 3,413 of the 8,180 delay minutes reported here. The split is drawn from 8,180 reported delay minutes.
Cancellations sit at 2.33% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and stage length
What a delay here costs
8.8% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last an hour and a half, which a normal layover absorbs.
At 2,300 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 71.5% on time across 429 flights, 5 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 5 points of difference.
One caution: this is a thin sample. 429 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking Delta on PHX to BOS
Put together: treat all of this as provisional. 429 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 76.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 419 completed flights over 12 months sit behind that.
Related
Where to go next
- PHX to BOS, every carrier
- Delta on BOS to PHX, the return leg
- American Airlines on PHX to BOS76.1%
- JetBlue Airways on PHX to BOS72.2%
- Delta Air Lines network-wide record
- Phoenix Sky Harbor International (PHX) delay statistics
- Boston Logan International (BOS) delay statistics
- The best time of day to fly, according to 7.05 million flight records
- Connecting flights: how much buffer the data says you need
Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.