Route reliability record
BOI→SLC
Boise to Salt Lake City
- Flights
- 1,732
- Period
- September 2025 to August 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 77.3%. When something does go wrong the average delay runs an hour and a half. That rests on 1,732 BOI to SLC flights, of which SkyWest Airlines flew 513 at 94.9% on time.
Best time to fly BOI to SLC: a 8am–11am departure, ideally on a Tuesday. Flights in that window arrived on time 95.6% of the time and Tuesday flights 93.1%, against 91.1% for the route overall.
Set against the rest of the country, this route's record is 14 points better than the US average of 77.3%. That gap is worth roughly 138 fewer late arrivals for every thousand flights.
Key figures
On time
91.1%
Arrivals under 15 minutes late, of 1,713 completed flights
Avg delay
84 min
Across delayed arrivals only, not all flights
Cancelled
0.98%
National rate is 1.89%
Best carrier
SkyWest
94.9% on time across 513 flights
These figures cover 1,732 flights between September 2025 and August 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.
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Carrier by carrier
Which airline is most reliable on BOI to SLC
The two carriers here are closely matched: 6 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 | 513 | 94.9% | 69 min | 0.19% | A+ |
| Delta Air Lines | 1,219 | 89.4% | 87 min | 1.31% | A |
No carrier stands out. SkyWest tops the table at 94.9%, 6 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.
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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 | 94.7% | 94.9% | 0.19% | 8am–11am, Sun | — |
| 2. BOI → SLCBoise to Salt Lake City | Delta Air Lines | 88.2% | 89.4% | 1.31% | 8am–11am, Fri | DL 2173 06:00 |
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 1,732 flights.
- 5am–8am365 flights90.5%
- 8am–11am406 flights95.6%
- 11am–2pm598 flights89.6%
- 2pm–5pm—
- 5pm–8pm363 flights88.9%
- 8pm–5am—
Scale runs 80% to 100%. Rows with fewer than 30 flights show a dash.
The early departures do better, though not dramatically: 95.6% on time for the 8am–11am window against 88.9% for 5pm–8pm. Worth taking if the schedule allows, not worth an extra connection. The 11am–2pm window is the busiest, with 598 flights scheduled in it.
Explore
Filter BOI to SLC by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On BOI to SLC, the best departure window is 8am–11am at 95.6% on time and the worst is 5pm–8pm at 88.9%, a real gap of 6.7 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am90.5%
- 8–11am95.6%
- 11am–2pm89.6%
- 2–5pm—
- 5–8pm88.9%
- 8pm–5am—
best all US flightsScale 60% to 100%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
Twelve months, one bar each, drawn from the same 1,732 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.
Across the week, Tuesday is the strongest day at 93.1% on time and Thursday the weakest at 87.7%, a spread of 5 points.
Delay causes
Why this route gets delayed
Carrier accounts for 57% of the 13,000 delay minutes carriers reported here, and the remaining four split what is left.
- 57%Carrier
- 27%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. It accounts for 7,364 of the 13,000 delay minutes reported here. The split is drawn from 12,809 reported delay minutes.
Cancellations sit at 0.98% against a national 1.89%, which is ordinary. Diversions add another 0.12%.
Connections and stage length
What a delay here actually costs
Badly late arrivals are rare here: only 3.1% land an hour or more behind schedule, against 8.3% 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 86.3% on time across 1,732 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 1,732 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: take the 8am–11am departure, avoid January if the dates are flexible, and if two carriers are within a few dollars of each other, SkyWest is the one with the record behind it. None of that guarantees an on-time arrival; it moves the odds by 7 points, which is the most any booking decision can do. 1,713 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 8.9% of the 1,732 flights in this analysis, against 22.7% 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 94.9% on time across 513 flights. Delta Air Lines is at the other end on 89.4%, a gap of 6 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 95.6% on time. The 5pm–8pm window is the weakest at 88.9%, 7 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 SLC94.9%
- Delta Air Lines on BOI to SLC89.4%
- BOI to SEA, a related route84.9%
- DEN to SLC, a related route78.2%
- BOI to DEN, a related route81.7%
- SkyWest Airlines on-time record94.9%
- Delta Air Lines on-time record89.4%
- The most punctual routes in the US, and the least
- Worst months to fly in the US, ranked by the data
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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.