Flight number record
UA 340
United Airlines · Atlanta to Denver
- Route
- ATL → DEN
- Departs
- 09:00
- Flights
- 277
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s UA 340, check with United Airlines.
UA 340 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 10 points better than the national rate of 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 277 flights, with a median arrival 9 minutes early.
Set against the rest of the country, UA 340's record is 10 points better than the US average of 77.6%. That gap is worth roughly 103 fewer late arrivals for every thousand flights.
Key figures
On time
87.9%
Arrivals under 15 minutes late, of 272 completed flights
Avg delay
72 min
Across delayed arrivals only, not all flights
Cancelled
1.44%
National rate is 1.81%
1 hour+ late
3.7%
National rate is 8.1%
These figures cover 277 flights between July 2025 and June 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.
Schedule
When UA 340 flies
UA 340 flies ATL to DEN without a single fixed slot. Its most common scheduled departure was 09:00, used on 169 of 277 flights, with 08:40 (36 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 09:00169 flights61.0%
- Departs 08:4036 flights13.0%
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 09:00 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 84.1%, and UA 340 runs 4 points better at 87.9%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
Against the route
UA 340 next to ATL to DEN
Every carrier on ATL to DEN combined arrived on time 77.6% of the time across 5,589 flights, so UA 340 is 10 points ahead of it. United flew 967 flights on the same city pair under all its flight numbers, including this one, and those ran 85.6% on time. Across its whole network United Airlines managed 79.0%, which this flight beats by 9 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 340thin sample | 277 | 87.9% | 72 min | 1.44% | A |
| All United Airlines on ATL–DEN | 967 | 85.6% | 78 min | 0.41% | A+ |
| All carriers on ATL–DEN | 5,589 | 77.6% | 60 min | 1.02% | B |
| United Airlines, whole network | 821,041 | 79.0% | 72 min | 1.01% | B |
Across the year
UA 340 quarter by quarter
UA 340 did not run the same all year. Its best quarter was Apr–Jun 2026 at 94.5% on time and its weakest Jan–Mar 2026 at 83.9%, a swing of 11 points on roughly 69 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 202577 flights84.0%
- Oct–Dec 202555 flights92.7%
- Jan–Mar 202690 flights83.9%
- Apr–Jun 202655 flights94.5%
Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.
By weekday, UA 340 ranged from 83.7% on Tuesday to 94.9% on Friday. With about 40 flights behind each day, a spread of 11 points is inside normal variation, so the day you fly is not worth changing for this flight.
Delay causes
Why UA 340 runs late
One category carries most of the weight here. Carrier accounts for 56% of the 2,364 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.
- 56%Carrier
- 33%National Airspace System
- 6%Security
- 5%Late-arriving aircraft
- 0%Extreme weather
The largest share of delay minutes, 56%, 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 1,318 of the 2,364 delay minutes reported here. The split is drawn from 2,364 delay minutes reported on UA 340.
Cancellations sit at 1.44% against a national 1.81%, which is ordinary. Diversions add another 0.36%.
Connections and routes
What a delay on this flight costs
Badly late arrivals are rare here: only 3.7% 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.
The 1,199 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 seven other city pairs in the data, including DEN to PWM (37), ABQ to ORD (35) and ORD to LGA (24), but none flew often enough under UA 340 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to ATL to DEN only.
One caution: this is a thin sample. 277 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 340
For a booking, UA 340 has one of the better records a US domestic flight can show: 87.9% on time and 1.44% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- ATL to DEN, every carrier and departure
- DEN to ATL, the return direction
- Delta Air Lines 519 on the same route64.8%
- United Airlines 235 on the same route80.2%
- Frontier Airlines 3293 on the same route79.2%
- Delta Air Lines 746 on the same route66.3%
- Delta Air Lines 706 on the same route85.5%
- Delta Air Lines 530 on the same route81.6%
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- 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 to read this site: grades, sample sizes, and honest caveats
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.