Carrier route record
DLSLC→BIL
Delta Air Lines · Salt Lake City to Billings
- Flights
- 366
- Period
- July 2025 to June 2026
- Share of route
- 34%
- Carriers
- 2
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on SLC to BIL lands a B+, 4 points better than the national rate of 77.6%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 366 flights, with a median arrival 8 minutes early.
Set against the rest of the country, Delta's SLC to BIL record is 4 points better than the US average of 77.6%. That gap is worth roughly 40 fewer late arrivals for every thousand flights.
Key figures
On time
81.6%
Arrivals under 15 minutes late, of 364 completed flights
Avg delay
70 min
Across delayed arrivals only, not all flights
Cancelled
0.55%
National rate is 1.81%
Whole route
88.4%
Every carrier on SLC to BIL, 1,074 flights
These figures cover 366 flights between July 2025 and June 2026. The median arrival is 8 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
Delta against every carrier on SLC to BIL
Delta flew 366 of the 1,074 flights on SLC to BIL, about 34% of it. Its 81.6% on time is 7 points worse than the route as a whole, which runs 88.4%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from SkyWest at 91.9% to Delta at 81.6%.
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 | 708 | 91.9% | 63 min | 0.56% | A+ |
| Delta Air Lines (this page) | 366 | 81.6% | 70 min | 0.55% | B+ |
Flight by flight
Delta flight numbers on SLC to BIL
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 366 flights.
The overnight block holds up unusually well at 81.5% 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 76.7% on time, 17 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. August was the busiest month here, with 32 flights.
Across the week, Friday is the strongest day at 90.0% on time and Sunday the weakest at 73.1%. 17 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Delta runs late on this route
One category carries most of the weight here. Carrier accounts for 55% of the 4,715 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.
- 55%Carrier
- 30%Late-arriving aircraft
- 13%Extreme weather
- 3%National Airspace System
Extreme weather accounts for 13% 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 2.1 times the usual weather exposure. The split is drawn from 4,715 reported delay minutes.
The largest share of delay minutes, 55%, 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 2,577 of the 4,715 delay minutes reported here.
Cancellations are rare at 0.55%, 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 costs
6.3% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last a little over 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 93.1% on time across 366 flights, 12 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 12 points of difference.
One caution: this is a thin sample. 366 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. 366 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 81.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 364 completed flights over 12 months sit behind that.
Related
Where to go next
- SLC to BIL, every carrier
- Delta on BIL to SLC, the return leg
- SkyWest Airlines on SLC to BIL91.9%
- Delta Air Lines network-wide record
- Salt Lake City International (SLC) delay statistics
- Worst months to fly in the US, ranked by the data
- Late aircraft, weather, or the airline: what actually causes US flight delays
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.