Flight number record
UA 2173
United Airlines · Boise to Denver
- Route
- BOI → DEN
- Departs
- 14:40
- Flights
- 364
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s UA 2173, check with United Airlines.
UA 2173 sits in the middle of the pack with a B+. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.6%. The late ones land an hour and a half behind schedule. That rests on 364 flights, with a median arrival 4 minutes early.
Key figures
On time
75.3%
Arrivals under 15 minutes late, of 360 completed flights
Avg delay
93 min
Across delayed arrivals only, not all flights
Cancelled
0.27%
National rate is 1.81%
1 hour+ late
10.8%
National rate is 8.1%
These figures cover 364 flights between July 2025 and June 2026. Beyond the headline rate, 10.8% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Schedule
When UA 2173 flies
UA 2173 flies BOI to DEN without a single fixed slot. Its most common scheduled departure was 14:40, used on 101 of 364 flights, with 14:37 (69 flights) and 14:32 (49 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 14:40101 flights27.7%
- Departs 14:3769 flights19.0%
- Departs 14:3249 flights13.5%
Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 14:40 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 72.4%, and UA 2173 runs 3 points better at 75.3%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
Against the route
UA 2173 next to BOI to DEN
Every carrier on BOI to DEN combined arrived on time 80.9% of the time across 3,035 flights, so UA 2173 is 6 points behind it. United flew 946 flights on the same city pair under all its flight numbers, including this one, and those ran 80.1% on time. Across its whole network United Airlines managed 79.0%, which this flight trails by 4 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 2173thin sample | 364 | 75.3% | 93 min | 0.27% | B+ |
| All United Airlines on BOI–DEN | 946 | 80.1% | 89 min | 0.53% | B+ |
| All carriers on BOI–DEN | 3,035 | 80.9% | 77 min | 0.20% | B+ |
| United Airlines, whole network | 821,041 | 79.0% | 72 min | 1.01% | B |
Across the year
UA 2173 quarter by quarter
UA 2173 did not run the same all year. Its best quarter was Jan–Mar 2026 at 85.6% on time and its weakest Jul–Sep 2025 at 55.6%, a swing of 30 points on roughly 91 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
- Jul–Sep 202592 flights55.6%
- Oct–Dec 202591 flights80.2%
- Jan–Mar 202690 flights85.6%
- Apr–Jun 202691 flights79.8%
Scale runs 45% to 90%. Rows with fewer than 30 flights show a dash.
By weekday, UA 2173 did best on Tuesday at 84.0% on time and worst on Friday at 63.5%. Each day rests on about 52 flights, so a gap of 21 points is worth noticing but could still narrow in another year.
Delay causes
Why UA 2173 runs late
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 8,297 reported delay minutes.
- 36%Carrier
- 31%National Airspace System
- 27%Late-arriving aircraft
- 6%Extreme weather
The largest share of delay minutes, 36%, 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 2,960 of the 8,297 delay minutes reported here. The split is drawn from 8,297 delay minutes reported on UA 2173.
Cancellations are rare at 0.27%, 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 routes
What a delay on this flight costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.8% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
The 649 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The same number turns up on one other city pair in the data, including DEN to HDN (94), but none flew often enough under UA 2173 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to BOI to DEN only.
One caution: this is a thin sample. 364 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 UA 2173
For a booking, UA 2173 is one of the weaker ways to fly BOI to DEN: 6 points below the route as a whole. If the schedule allows, compare it with the other departures listed on the route page before settling on this one.
Related
Where to go next
- BOI to DEN, every carrier and departure
- DEN to BOI, the return direction
- United Airlines 1782 on the same route91.7%
- Denver International (DEN) delay statistics
- United Airlines on-time record
- Every United Airlines flight number with a record
- The most and least reliable flight numbers in the US
- How often a connection fails at the major US hubs
A flight number here means United Airlines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.
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.