Route reliability record
BIL→SLC
Billings to Salt Lake City
- Flights
- 1,074
- Period
- July 2025 to June 2026
- Distance
- 387 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 1,074 BIL to SLC flights, of which Delta Air Lines flew 366 at 93.1% on time.
Best time to fly BIL to SLC: a 11am–2pm departure, ideally on a Monday. Flights in that window arrived on time 95.0% of the time and Monday flights 94.8%, against 91.6% 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 140 fewer late arrivals for every thousand flights.
Key figures
On time
91.6%
Arrivals under 15 minutes late, of 1,066 completed flights
Avg delay
84 min
Across delayed arrivals only, not all flights
Cancelled
0.65%
National rate is 1.81%
Best carrier
Delta
93.1% on time across 366 flights
These figures cover 1,074 flights between July 2025 and June 2026. The median arrival is 14 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 BIL to SLC
The two carriers here are closely matched: 2 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 |
|---|---|---|---|---|---|
| Delta Air Lines | 366 | 93.1% | 97 min | 0.55% | A+ |
| SkyWest Airlines | 708 | 90.7% | 79 min | 0.71% | A+ |
No carrier stands out. Delta tops the table at 93.1%, 2 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on BIL 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 Billings 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. BIL → SLCBillings to Salt Lake City | Delta Air Lines | 92.6% | 93.1% | 0.55% | 5am–8am, Wed | DL 1360 05:25 |
| 2. BIL → SLCBillings to Salt Lake City | SkyWest Airlines | 90.1% | 90.7% | 0.71% | 11am–2pm, Mon | OO 3828 18:15 |
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 1,074 flights.
- 5am–8am365 flights93.1%
- 8am–11am—
- 11am–2pm363 flights95.0%
- 2pm–5pm2 flights—
- 5pm–8pm344 flights86.2%
- 8pm–5am—
Scale runs 80% to 100%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 11am–2pm slot at 95.0% on time, ahead of 5pm–8pm at 86.2%. 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 5am–8am window is the busiest, with 365 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 13 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.
December is the weak month at 84.4% on time, against 97.8% in September. 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 93 flights.
Across the week, Monday is the strongest day at 94.8% on time and Friday the weakest at 89.0%. 6 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. Carrier accounts for 77% of the 7,552 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.
- 77%Carrier
- 11%Extreme weather
- 9%National Airspace System
- 3%Late-arriving aircraft
The largest share of delay minutes, 77%, 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 5,829 of the 7,552 delay minutes reported here. The split is drawn from 7,552 reported delay minutes.
Cancellations are rare at 0.65%, 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 3.3% 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 387 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 11am–2pm window matters as much as it does.
The return leg is a different operation and performs like one: it runs 88.4% on time across 1,074 flights, 3 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 3 points of difference.
One caution: this is a thin sample. 1,074 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.
Work out the risk of missing a connection in SLC after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 1,074 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 91.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,066 completed flights over 12 months sit behind that.
Common questions
BIL to SLC questions
How often is BIL 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 8.4% of the 1,074 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 BIL to SLC?
Delta Air Lines leads at 93.1% on time across 366 flights. SkyWest Airlines is at the other end on 90.7%, a gap of 2 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 BIL to SLC?
The 11am–2pm departure window is the strongest at 95.0% on time. The 5pm–8pm window is the weakest at 86.2%, 9 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 December delays on BIL to SLC?
December is the weakest month at 84.4% on time, compared with 97.8% in September. Across the year that is 13 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 BIL — the return legseparate record
- Salt Lake City International (SLC) delay statistics
- Delta Air Lines on BIL to SLC93.1%
- SkyWest Airlines on BIL to SLC90.7%
- BIL to DEN, a related route82.3%
- DEN to SLC, a related route77.5%
- PHX to SLC, a related route83.0%
- Delta Air Lines on-time record93.1%
- SkyWest Airlines on-time record90.7%
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. BIL to SLC and SLC to BIL 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.