Carrier route record
DLSLC→BIL
Delta Air Lines · Salt Lake City to Billings
- Flights
- 365
- Period
- September 2025 to August 2026
- Share of route
- 34%
- Carriers
- 2
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on SLC to BIL lands a B+, 2 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 365 flights, with a median arrival 9 minutes early.
The US average over the same twelve months is 77.3%, so there is little to separate Delta on SLC to BIL from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
79.7%
Arrivals under 15 minutes late, of 364 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
0.27%
National rate is 1.89%
Whole route
87.2%
Every carrier on SLC to BIL, 1,074 flights
These figures cover 365 flights between September 2025 and August 2026. The median arrival is 9 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
Delta against every carrier on SLC to BIL
Delta flew 365 of the 1,074 flights on SLC to BIL, about 34% of it. Its 79.7% on time is 8 points worse than the route as a whole, which runs 87.2%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from SkyWest at 91.1% to Delta at 79.7%.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 709 | 91.1% | 70 min | 0.56% | A+ |
| Delta Air Lines (this page) | 365 | 79.7% | 58 min | 0.27% | B+ |
Flight by flight
Delta flight numbers on SLC to BIL
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Departure window
When Delta runs best on this route
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 365 flights.
The overnight block holds up unusually well at 79.6% on time across 364 flights. Red-eyes fly into empty airspace and empty gates, and they are the first rotation of the aircraft's day rather than the last. The 8pm–5am window is the busiest, with 364 flights scheduled in it.
Across the year
Delta on SLC to BIL through the year
July is the worst month at 61.3% on time, 32 points below November, the best at 93.3%. 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. January was the busiest month here, with 31 flights.
Across the week, Saturday is the strongest day at 88.5% on time and Sunday the weakest at 71.2%, a spread of 17 points.
Arrival by arrival
How late Delta on SLC to BIL runs when it is late
Delta on SLC to BIL often beats the schedule: 129 of 364 completed flights, 35%, arrived 15 minutes or more early. The 74 late arrivals split 26 under half an hour, 22 between 30 and 60 minutes, and 26 an hour or more.
- 15+ min early129 flights35.4%
- Within 15 min161 flights44.2%
- 15–29 min late26 flights7.1%
- 30–59 min late22 flights6.0%
- 1–2 hours late22 flights6.0%
- 2+ hours late4 flights1.1%
Scale runs 0% to 100%.
Share of 364 completed flights by arrival against schedule.
21 of 92 late departures made up the time and arrived on time, 23% of them. Only 3 left on time and still arrived late.
The worst days
Worst days for Delta on SLC to BIL
The latest arrival of the period was on 27 October 2025, 10 hours 12 minutes behind schedule; most of its delay minutes were filed as extreme weather. On three of the five worst days the largest share was filed as a late-arriving aircraft.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 27 October 2025 | 10 hours 12 minutes | Extreme weather |
| 25 May 2026 | 3 hours 15 minutes | Carrier |
| 7 June 2026 | 2 hours 21 minutes | Late-arriving aircraft |
| 1 January 2026 | 2 hours 4 minutes | Late-arriving aircraft |
| 25 January 2026 | 1 hour 58 minutes | Late-arriving aircraft |
Delay causes
Why Delta runs late on this route
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 4,312 reported delay minutes.
- 41%Late-arriving aircraft
- 41%Carrier
- 14%Extreme weather
- 4%National Airspace System
Extreme weather accounts for 14% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.3 times the usual weather exposure. The split is drawn from 4,312 reported delay minutes.
41% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 4,312 reported delay minutes here, that single category outweighs weather by 3 to one.
Cancellations are rare at 0.27%, 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 costs
7.1% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
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 8pm–5am window matters as much as it does.
The return leg is a different operation and performs like one: it runs 94.0% on time across 365 flights, 14 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 14 points of difference.
One caution: this is a thin sample. 365 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.
What to do with this
Booking Delta on SLC to BIL
Put together: treat all of this as provisional. 365 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 79.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 364 completed flights over 12 months sit behind that.
Related
Where to go next
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.