Route reliability record
BOI→SLC
Boise to Salt Lake City
- Flights
- 1,740
- Period
- July 2025 to June 2026
- Distance
- 290 mi
- Carriers
- 2
This route earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 14 points better than the national rate of 77.6%. When something does go wrong the average delay runs an hour and a half. That rests on 1,740 BOI to SLC flights, of which SkyWest Airlines flew 517 at 95.3% on time.
Best time to fly BOI to SLC: a 8am–11am departure, ideally on a Saturday. Flights in that window arrived on time 95.2% of the time and Saturday flights 93.1%, against 92.0% for the route overall.
Set against the rest of the country, this route's record is 14 points better than the US average of 77.6%. That gap is worth roughly 144 fewer late arrivals for every thousand flights.
Key figures
On time
92.0%
Arrivals under 15 minutes late, of 1,720 completed flights
Avg delay
85 min
Across delayed arrivals only, not all flights
Cancelled
0.98%
National rate is 1.81%
Best carrier
SkyWest
95.3% on time across 517 flights
These figures cover 1,740 flights between July 2025 and June 2026. The median arrival is 12 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 SLC
The two carriers here are closely matched: 5 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 | 517 | 95.3% | 47 min | 0.19% | A+ |
| Delta Air Lines | 1,223 | 90.5% | 93 min | 1.31% | A |
No carrier stands out. SkyWest tops the table at 95.3%, 5 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on BOI to SLC
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
Best ways to make this trip
The most reliable ways to fly Boise to Salt Lake City
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 → SLCBoise to Salt Lake City | SkyWest Airlines | 95.1% | 95.3% | 0.19% | 8am–11am, Mon | — |
| 2. BOI → SLCBoise to Salt Lake City | Delta Air Lines | 89.3% | 90.5% | 1.31% | 8am–11am, Fri | DL 1744 10:45 |
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 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 1,740 flights.
- 5am–8am365 flights91.1%
- 8am–11am435 flights95.2%
- 11am–2pm576 flights90.5%
- 2pm–5pm—
- 5pm–8pm364 flights91.4%
- 8pm–5am—
Scale runs 80% to 100%. Rows with fewer than 30 flights show a dash.
The early departures do better, though not dramatically: 95.2% on time for the 8am–11am window against 90.5% for 11am–2pm. Worth taking if the schedule allows, not worth an extra connection. The 11am–2pm window is the busiest, with 576 flights scheduled in it.
Across the year
When delays peak on this route
Twelve months, one bar each, drawn from the same 1,740 flights. The strip shows how much of this route's record is set by the calendar rather than by the operation.
January is the weak month at 85.1% on time, against 96.1% in May. 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. May was the busiest month here, with 155 flights.
The day of the week is close to irrelevant here: 4 points separates the best day from the worst. Weekly demand peaks are not what drives the delays on this operation.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Carrier accounts for 57% of the 12,000 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.
- 57%Carrier
- 28%Late-arriving aircraft
- 10%National Airspace System
- 5%Extreme weather
The largest share of delay minutes, 57%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 6,666 of the 12,000 delay minutes reported here. The split is drawn from 11,677 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 95.2% on time here.
Cancellations sit at 0.98% against a national 1.81%, which is ordinary. Diversions add another 0.17%.
Connections and stage length
What a delay here actually costs
Badly late arrivals are rare here: only 2.7% 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.
At 290 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 8am–11am window matters as much as it does.
The return leg is a different operation and performs like one: it runs 87.1% on time across 1,742 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.
The sample behind these figures is 1,740 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 SLC after this flight
What to do with this
Booking this route
Put together: this route's record is 92.0% on time with 0.98% cancelled, worth an A+. The largest single lever is the 8am–11am departure window, and the numbers below the table are where the reasoning behind that lives. 1,720 completed flights over 12 months sit behind that.
Common questions
BOI to SLC questions
How often is BOI to SLC delayed?
About one flight in twelve arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 8.0% of the 1,740 flights in this analysis, against 22.4% nationally. Delayed flights are late by an hour and a half on average.
Which airline is most reliable on BOI to SLC?
SkyWest Airlines leads at 95.3% on time across 517 flights. Delta Air Lines is at the other end on 90.5%, a gap of 5 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 SLC?
The 8am–11am departure window is the strongest at 95.2% on time. The 11am–2pm window is the weakest at 90.5%, 5 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 January delays on BOI to SLC?
January is the weakest month at 85.1% on time, compared with 96.1% in May. Across the year that is 11 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
- SLC to BOI — the return legseparate record
- Salt Lake City International (SLC) delay statistics
- SkyWest Airlines on BOI to SLC95.3%
- Delta Air Lines on BOI to SLC90.5%
- BOI to SEA, a related route85.7%
- DEN to SLC, a related route77.5%
- BOI to DEN, a related route80.9%
- SkyWest Airlines on-time record95.3%
- Delta Air Lines on-time record90.5%
- Worst months to fly in the US, ranked by the data
- The best time of day to fly, according to 7.04 million flight records
Direction matters. BOI to SLC and SLC 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.