Flight number record
UA 340
United Airlines · Atlanta to Denver
- Route
- ATL → DEN
- Departs
- 09:00
- Flights
- 286
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 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 14 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 286 flights, with a median arrival 11 minutes early.
Set against the rest of the country, UA 340's record is 14 points better than the US average of 77.3%. That gap is worth roughly 138 fewer late arrivals for every thousand flights.
Key figures
On time
91.1%
Arrivals under 15 minutes late, of 282 completed flights
Avg delay
89 min
Across delayed arrivals only, not all flights
Cancelled
1.05%
National rate is 1.89%
1 hour+ late
2.8%
National rate is 8.3%
These figures cover 286 flights between September 2025 and August 2026. The median arrival is 11 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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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 149 of 286 flights, with 08:40 (36 flights) and 07:30 (33 flights) next.
- Departs 09:00149 flights52.1%
- Departs 08:4036 flights12.6%
- Departs 07:3033 flights11.5%
Scale runs 0% to 100%.
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 83.9%, and UA 340 runs 7 points better at 91.1%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
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Against the route
UA 340 next to ATL to DEN
Every carrier on ATL to DEN combined arrived on time 78.0% of the time across 5,594 flights, so UA 340 is 13 points ahead of it. United flew 923 flights on the same city pair under all its flight numbers, including this one, and those ran 85.9% on time. Across its whole network United Airlines managed 78.8%, which this flight beats by 12 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 340thin sample | 286 | 91.1% | 89 min | 1.05% | A |
| All United Airlines on ATL–DEN | 923 | 85.9% | 84 min | 0.43% | A+ |
| All carriers on ATL–DEN | 5,594 | 78.0% | 61 min | 1.11% | B |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 340 quarter by quarter
UA 340 did not run the same all year. Its best quarter was Jul–Sep 2026 at 96.4% on time and its weakest Jan–Mar 2026 at 83.9%, a swing of 13 points on roughly 72 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 202530 flights—
- Oct–Dec 202555 flights92.7%
- Jan–Mar 202690 flights83.9%
- Apr–Jun 202655 flights94.5%
- Jul–Sep 202656 flights96.4%
Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.
By weekday, UA 340 ranged from 85.7% on Tuesday to 95.2% on Monday. With about 41 flights behind each day, a spread of 10 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late UA 340 runs when it is late
UA 340 often beats the schedule: 111 of 282 completed flights, 39%, arrived 15 minutes or more early. The 25 late arrivals split 8 under half an hour, 9 between 30 and 60 minutes, and 8 an hour or more.
- 15+ min early111 flights39.4%
- Within 15 min146 flights51.8%
- 15–29 min late8 flights2.8%
- 30–59 min late9 flights3.2%
- 1–2 hours late3 flights1.1%
- 2+ hours late5 flights1.8%
Scale runs 0% to 100%.
Share of 282 completed flights by arrival against schedule.
5 of 21 late departures made up the time and arrived on time, 24% of them. 9 flights left on time and still arrived late.
The worst days
Worst days for UA 340
The latest arrival of the period was on 10 August 2026, 6 hours 55 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 10 August 2026 | 6 hours 55 minutes | Carrier |
| 21 October 2025 | 6 hours 39 minutes | Carrier |
| 24 April 2026 | 5 hours 40 minutes | Carrier |
| 17 February 2026 | 2 hours 35 minutes | National Airspace System |
| 3 December 2025 | 2 hours 15 minutes | National Airspace System |
Delay causes
Why UA 340 runs late
Carrier accounts for 65% of the 2,212 delay minutes carriers reported here, and the remaining four split what is left.
- 65%Carrier
- 32%National Airspace System
- 3%Late-arriving aircraft
- 0%Extreme weather
The largest share of delay minutes, 65%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,440 of the 2,212 delay minutes reported here. The split is drawn from 2,212 delay minutes reported on UA 340.
Cancellations sit at 1.05% against a national 1.89%, which is ordinary. Diversions add another 0.35%.
Connections and routes
What a delay on this flight costs
Badly late arrivals are rare here: only 2.8% land an hour or more behind schedule, against 8.3% 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.
The same number turns up on four 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. 286 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: 91.1% on time and 1.05% 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 route66.7%
- United Airlines 235 on the same route78.5%
- Delta Air Lines 746 on the same route67.8%
- Delta Air Lines 706 on the same route84.7%
- Frontier Airlines 3293 on the same route81.2%
- Delta Air Lines 530 on the same route80.5%
- 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
- The best day of the week to fly, and why it is the second lever
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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.