Route reliability record
BOI→PHX
Boise to Phoenix
- Flights
- 1,985
- Period
- July 2025 to June 2026
- Distance
- 735 mi
- Carriers
- 5
This route lands a B+, 6 points better than the national rate of 77.6%. About one flight in six arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 1,985 BOI to PHX flights, of which SkyWest Airlines flew 1,000 at 86.5% on time.
Best time to fly BOI to PHX: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 95.6% of the time and Saturday flights 88.0%, against 83.9% for the route overall.
Set against the rest of the country, this route's record is 6 points better than the US average of 77.6%. That gap is worth roughly 63 fewer late arrivals for every thousand flights.
Key figures
On time
83.9%
Arrivals under 15 minutes late, of 1,970 completed flights
Avg delay
75 min
Across delayed arrivals only, not all flights
Cancelled
0.50%
National rate is 1.81%
Best carrier
SkyWest
86.5% on time across 1,000 flights
These figures cover 1,985 flights between July 2025 and June 2026. The median arrival is 8 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Carrier by carrier
Which airline is most reliable on BOI to PHX
The two carriers here are closely matched: 4 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 1,000 | 86.5% | 95 min | 0.60% | A+ |
| Southwest Airlines | 813 | 82.8% | 60 min | 0.49% | B+ |
| Envoy Airthin sample | 115 | 75.7% | 45 min | 0.00% | B+ |
| American Airlinesthin sample | 52 | 73.1% | 103 min | 0.00% | C+ |
| Alaska Airlinesthin sample | 5 | 60.0% | 21 min | 0.00% | D+ |
No carrier stands out. SkyWest tops the table at 86.5%, 4 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Best ways to make this trip
The most reliable ways to fly Boise to Phoenix
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. BOI → PHXBoise to Phoenix | SkyWest Airlines | 86.0% | 86.5% | 0.60% | 5am–8am, Sat | — |
| 2. BOI → PHXBoise to Phoenix | Southwest Airlines | 82.4% | 82.8% | 0.49% | 5am–8am, Sun | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 23 points, against 4 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am688 flights95.6%
- 8am–11am105 flights91.4%
- 11am–2pm258 flights83.9%
- 2pm–5pm512 flights77.8%
- 5pm–8pm394 flights72.9%
- 8pm–5am28 flights—
Scale runs 65% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 95.6% of the time, against 72.9% for the evening window. That is 23 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 688 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 14 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
June is the worst month at 77.6% on time, 14 points below March, the best at 91.9%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. October was the busiest month here, with 198 flights.
Across the week, Saturday is the strongest day at 88.0% on time and Thursday the weakest at 79.8%. 8 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 51% of the 24,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 51%Late-arriving aircraft
- 30%Carrier
- 13%National Airspace System
- 6%Extreme weather
- 0%Security
51% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 24,000 reported delay minutes here, that single category outweighs weather by 8 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 23,771 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 95.6% on time here.
Cancellations are rare at 0.50%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here actually costs
Badly late arrivals are rare here: only 4.8% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
The 735 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg is a different operation and performs like one: it runs 80.4% on time across 1,986 flights, 4 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 4 points of difference.
The sample behind these figures is 1,985 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
Work out the risk of missing a connection in PHX after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. March runs 91.9% on time and June 77.6%, a swing of 14 points. If the dates move at all, move them out of June before you think about anything else. 1,970 completed flights over 12 months sit behind that.
Common questions
BOI to PHX questions
How often is BOI to PHX delayed?
About one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 16.1% of the 1,985 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on BOI to PHX?
SkyWest Airlines leads at 86.5% on time across 1,000 flights. Southwest Airlines is at the other end on 82.8%, a gap of 4 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on BOI to PHX?
The 5am–8am departure window is the strongest at 95.6% on time. The 5pm–8pm window is the weakest at 72.9%, 23 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are June delays on BOI to PHX?
June is the weakest month at 77.6% on time, compared with 91.9% in March. Across the year that is 14 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- PHX to BOI — the return legseparate record
- Phoenix Sky Harbor International (PHX) delay statistics
- SkyWest Airlines on BOI to PHX86.5%
- Southwest Airlines on BOI to PHX82.8%
- Envoy Air on BOI to PHX75.7%
- BOI to SEA, a related route85.7%
- DEN to PHX, a related route75.7%
- BOI to DEN, a related route80.9%
- SkyWest Airlines on-time record86.5%
- Southwest Airlines on-time record82.8%
- Envoy Air on-time record75.7%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. BOI to PHX and PHX to BOI are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.