Carrier route record
DLBOS→PHX
Delta Air Lines · Boston to Phoenix
- 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 BOS to PHX sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.3%. The late ones land roughly 55 minutes behind schedule. That rests on 429 flights, with a median arrival 1 minute early.
The national on-time rate over the same period is 77.3%, so Delta on BOS to PHX runs 6 points behind the country as a whole. Across a thousand flights that is about 58 extra late arrivals.
Key figures
On time
71.5%
Arrivals under 15 minutes late, of 418 completed flights
Avg delay
53 min
Across delayed arrivals only, not all flights
Cancelled
1.86%
National rate is 1.89%
Whole route
77.3%
Every carrier on BOS to PHX, 2,012 flights
These figures cover 429 flights between September 2025 and August 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Carrier by carrier
Delta against every carrier on BOS to PHX
Delta flew 429 of the 2,012 flights on BOS to PHX, about 21% of it. Its 71.5% on time is 6 points worse than the route as a whole, which runs 77.3%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from American at 80.0% to Delta at 71.5%. 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 |
|---|---|---|---|---|---|
| American Airlines | 1,310 | 80.0% | 80 min | 1.60% | B |
| JetBlue Airwaysthin sample | 273 | 73.5% | 69 min | 1.83% | C |
| Delta Air Lines (this page) | 429 | 71.5% | 53 min | 1.86% | C |
Flight by flight
Delta flight numbers on BOS to PHX
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 is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 429 flights.
- 5am–8am—
- 8am–11am213 flights73.6%
- 11am–2pm1 flights—
- 2pm–5pm—
- 5pm–8pm215 flights69.9%
- 8pm–5am—
Scale runs 60% to 80%. Rows with fewer than 30 flights show a dash.
The 8am–11am window is the strongest at 73.6% on time. The full set of windows spans 4 points.
Across the year
Delta on BOS to PHX through the year
December is the weak month at 41.0% on time, against 95.9% in March. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. March was the busiest month here, with 49 flights.
Across the week, Monday is the strongest day at 79.4% on time and Saturday the weakest at 64.4%, a spread of 15 points.
Arrival by arrival
How late Delta on BOS to PHX runs when it is late
The 119 late arrivals split 49 under half an hour, 38 between 30 and 60 minutes, and 32 an hour or more.
- 15+ min early102 flights24.4%
- Within 15 min197 flights47.1%
- 15–29 min late49 flights11.7%
- 30–59 min late38 flights9.1%
- 1–2 hours late21 flights5.0%
- 2+ hours late11 flights2.6%
Scale runs 0% to 100%.
Share of 418 completed flights by arrival against schedule.
10 of 72 late departures made up the time and arrived on time, 14% of them. In the other direction, 57 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 PHX.
The worst days
Worst days for Delta on BOS to PHX
The latest arrival of the period was on 7 September 2025, 4 hours 30 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The five worst days are spread across September, February and October, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 7 September 2025 | 4 hours 30 minutes | Late-arriving aircraft |
| 24 September 2025 | 4 hours 20 minutes | Late-arriving aircraft |
| 13 February 2026 | 3 hours 45 minutes | Carrier |
| 15 October 2025 | 3 hours 31 minutes | Extreme weather |
| 15 February 2026 | 2 hours 58 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 6,304 reported delay minutes.
- 39%National Airspace System
- 30%Late-arriving aircraft
- 26%Carrier
- 5%Extreme weather
39% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 2,429 minutes out of 6,304, against a national NAS share of 21%. The split is drawn from 6,304 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 73.6% on time here.
Cancellations sit at 1.86% against a national 1.89%, which is ordinary. Diversions add another 0.70%.
Connections and stage length
What a delay here costs
7.7% 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 roughly 55 minutes, 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 76.6% on time across 429 flights, 5 points above 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 BOS to PHX
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 71.5% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 418 completed flights over 12 months sit behind that.
Related
Where to go next
- BOS to PHX, every carrier
- Delta on PHX to BOS, the return leg
- American Airlines on BOS to PHX80.0%
- JetBlue Airways on BOS to PHX73.5%
- Delta Air Lines network-wide record
- Boston Logan International (BOS) delay statistics
- Phoenix Sky Harbor International (PHX) delay statistics
- Worst months to fly in the US, ranked by the data
- The best day of the week to fly, and why it is the second lever
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.