Carrier route record
UABIL→DEN
United Airlines · Billings to Denver
- Flights
- 725
- Period
- September 2025 to August 2026
- Share of route
- 41%
- Carriers
- 2
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with United Airlines.
United on BIL to DEN earns a B+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 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 725 flights, with a median arrival 14 minutes early.
Set against the rest of the country, United's BIL to DEN record is 7 points better than the US average of 77.3%. That gap is worth roughly 68 fewer late arrivals for every thousand flights.
Key figures
On time
84.1%
Arrivals under 15 minutes late, of 719 completed flights
Avg delay
85 min
Across delayed arrivals only, not all flights
Cancelled
0.28%
National rate is 1.89%
Whole route
82.5%
Every carrier on BIL to DEN, 1,774 flights
These figures cover 725 flights between September 2025 and August 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.
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Carrier by carrier
United against every carrier on BIL to DEN
United flew 725 of the 1,774 flights on BIL to DEN, about 41% of it. Its 84.1% on time is 2 points better than the route as a whole, which runs 82.5%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from United at 84.1% to SkyWest at 81.3%.
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 |
|---|---|---|---|---|---|
| United Airlines (this page) | 725 | 84.1% | 85 min | 0.28% | B+ |
| SkyWest Airlines | 1,049 | 81.3% | 91 min | 1.43% | B |
Flight by flight
United flight numbers on BIL to DEN
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 United runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 15 points, against half a point between the best and worst carrier.
- 5am–8am365 flights91.7%
- 8am–11am—
- 11am–2pm1 flights—
- 2pm–5pm359 flights76.4%
- 5pm–8pm—
- 8pm–5am—
Scale runs 70% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 91.7% of the time, against 76.4% for the afternoon window. That is 15 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 365 flights scheduled in it.
Across the year
United on BIL to DEN through the year
July is the worst month at 72.9% on time, 25 points below April, the best at 98.3%. 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 62 flights.
Across the week, Sunday is the strongest day at 90.0% on time and Saturday the weakest at 77.5%, a spread of 13 points.
Arrival by arrival
How late United on BIL to DEN runs when it is late
United on BIL to DEN often beats the schedule: 358 of 719 completed flights, 50%, arrived 15 minutes or more early. The 114 late arrivals split 35 under half an hour, 34 between 30 and 60 minutes, and 45 an hour or more.
- 15+ min early358 flights49.8%
- Within 15 min247 flights34.4%
- 15–29 min late35 flights4.9%
- 30–59 min late34 flights4.7%
- 1–2 hours late19 flights2.6%
- 2+ hours late26 flights3.6%
Scale runs 0% to 100%.
Share of 719 completed flights by arrival against schedule.
15 of 95 late departures made up the time and arrived on time, 16% of them. 34 flights left on time and still arrived late.
The worst days
Worst days for United on BIL to DEN
The latest arrival of the period was on 12 May 2026, 10 hours behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). On three of the five worst days the largest share was filed as a late-arriving aircraft.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 12 May 2026 | 10 hours | Carrier |
| 23 July 2026 | 7 hours 40 minutes | Late-arriving aircraft |
| 14 August 2026 | 7 hours 1 minute | National Airspace System |
| 6 March 2026 | 5 hours 57 minutes | Late-arriving aircraft |
| 18 October 2025 | 5 hours 19 minutes | Late-arriving aircraft |
Delay causes
Why United 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 9,703 reported delay minutes.
- 35%Late-arriving aircraft
- 32%National Airspace System
- 28%Carrier
- 4%Extreme weather
35% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 9,703 reported delay minutes here, that single category outweighs weather by 8 to one. The split is drawn from 9,703 reported delay minutes.
32% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 3,152 minutes out of 9,703, against a national NAS share of 21%.
Cancellations are rare at 0.28%, 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
6.3% 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 an hour and a half, which a normal layover absorbs.
At 455 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 5am–8am window matters as much as it does.
The return leg is a different operation and performs like one: it runs 79.2% on time across 725 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.
One caution: this is a thin sample. 725 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 United on BIL to DEN
Put together: treat all of this as provisional. 725 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 84.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 719 completed flights over 12 months sit behind that.
Related
Where to go next
- BIL to DEN, every carrier
- United on DEN to BIL, the return leg
- SkyWest Airlines on BIL to DEN81.3%
- United Airlines network-wide record
- Denver International (DEN) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
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.