Route reliability record
SLC→BOI
Salt Lake City to Boise
- Flights
- 1,732
- Period
- September 2025 to August 2026
- Distance
- 290 mi
- Carriers
- 2
This route earns an A+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 9 points better than the national rate of 77.3%. When something does go wrong the average delay runs about an hour. That rests on 1,732 SLC to BOI flights, of which SkyWest Airlines flew 513 at 91.8% on time.
Best time to fly SLC to BOI: a 2pm–5pm departure, ideally on a Tuesday. Flights in that window arrived on time 89.2% of the time and Tuesday flights 91.0%, against 86.3% for the route overall.
Set against the rest of the country, this route's record is 9 points better than the US average of 77.3%. That gap is worth roughly 90 fewer late arrivals for every thousand flights.
Key figures
On time
86.3%
Arrivals under 15 minutes late, of 1,717 completed flights
Avg delay
59 min
Across delayed arrivals only, not all flights
Cancelled
0.81%
National rate is 1.89%
Best carrier
SkyWest
91.8% on time across 513 flights
These figures cover 1,732 flights between September 2025 and August 2026. The median arrival is 10 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 SLC to BOI
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 91.8% of the time; Delta Air Lines manages 84.0%. Sample sizes sit next to every figure, because a two-point gap across 1,219 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 513 | 91.8% | 54 min | 0.19% | A+ |
| Delta Air Lines | 1,219 | 84.0% | 61 min | 1.07% | B |
SkyWest leads Delta by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on SLC to BOI
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 Salt Lake City to Boise
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. SLC → BOISalt Lake City to Boise | SkyWest Airlines | 91.6% | 91.8% | 0.19% | 8am–11am, Mon | — |
| 2. SLC → BOISalt Lake City to Boise | Delta Air Lines | 83.1% | 84.0% | 1.07% | 11am–2pm, Tue | DL 1744 08:15 |
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–8am—
- 8am–11am575 flights87.3%
- 11am–2pm141 flights87.9%
- 2pm–5pm363 flights89.2%
- 5pm–8pm28 flights—
- 8pm–5am625 flights83.4%
Scale runs 75% to 95%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 2pm–5pm slot at 89.2% on time, ahead of 8pm–5am at 83.4%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 8pm–5am window is the busiest, with 625 flights scheduled in it.
Explore
Filter SLC to BOI 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 SLC to BOI, the best departure window is 2pm–5pm at 89.2% on time and the worst is 8pm–5am at 83.4%, a real gap of 5.8 points. All US flights leaving 2pm–5pm ran 71.9%.
- 5–8am—
- 8–11am87.3%
- 11am–2pm87.9%
- 2–5pm89.2%
- 5–8pm—
- 8pm–5am83.4%
best all US flightsScale 60% to 95%. 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.
August is the worst month at 81.5% on time, 10 points below June, the best at 91.0%. 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. May was the busiest month here, with 155 flights.
Across the week, Tuesday is the strongest day at 91.0% on time and Sunday the weakest at 82.5%, a spread of 9 points.
Delay causes
Why this route gets delayed
Carrier accounts for 63% of the 14,000 delay minutes carriers reported here, and the remaining four split what is left.
- 63%Carrier
- 19%Late-arriving aircraft
- 11%Extreme weather
- 7%National Airspace System
The largest share of delay minutes, 63%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 8,751 of the 14,000 delay minutes reported here. The split is drawn from 13,955 reported delay minutes.
Cancellations are rare at 0.81%, below the national 1.89% 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 4.0% 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 2pm–5pm window matters as much as it does.
The return leg is a different operation and performs like one: it runs 91.1% on time across 1,732 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.
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 BOI after this flight
What to do with this
Booking this route
Put together: this route's record is 86.3% on time with 0.81% cancelled, worth an A+. The largest single lever is the 2pm–5pm departure window, and the numbers below the table are where the reasoning behind that lives. 1,717 completed flights over 12 months sit behind that.
Common questions
SLC to BOI questions
How often is SLC to BOI delayed?
About one flight in seven arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 13.7% of the 1,732 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on SLC to BOI?
SkyWest Airlines leads at 91.8% on time across 513 flights. Delta Air Lines is at the other end on 84.0%, a gap of 8 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 SLC to BOI?
The 2pm–5pm departure window is the strongest at 89.2% on time. The 8pm–5am window is the weakest at 83.4%, 6 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 August delays on SLC to BOI?
August is the weakest month at 81.5% on time, compared with 91.0% in June. Across the year that is 10 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
- BOI to SLC — the return legseparate record
- Salt Lake City International (SLC) delay statistics
- SkyWest Airlines on SLC to BOI91.8%
- Delta Air Lines on SLC to BOI84.0%
- SLC to DEN, a related route79.0%
- SEA to BOI, a related route86.3%
- SLC to PHX, a related route83.5%
- SkyWest Airlines on-time record91.8%
- Delta Air Lines on-time record84.0%
- Worst months to fly in the US, ranked by the data
- Late aircraft, weather, or the airline: what actually causes US flight delays
Direction matters. SLC to BOI and BOI to SLC 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.