Flight number record
UA 1727
United Airlines · Buffalo to Denver
- Route
- BUF → DEN
- Departs
- 09:00
- Flights
- 293
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 1727, check with United Airlines.
UA 1727 lands a B+, 7 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 293 flights, with a median arrival 4 minutes early.
Set against the rest of the country, UA 1727's record is 7 points better than the US average of 77.3%. That gap is worth roughly 66 fewer late arrivals for every thousand flights.
Key figures
On time
83.9%
Arrivals under 15 minutes late, of 292 completed flights
Avg delay
67 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.89%
1 hour+ late
5.5%
National rate is 8.3%
These figures cover 293 flights between September 2025 and August 2026. The median arrival is 4 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 1727 flies
UA 1727 flies BUF to DEN without a single fixed slot. Its most common scheduled departure was 09:00, used on 81 of 293 flights, with 08:25 (52 flights) and 08:30 (40 flights) next.
- Departs 09:0081 flights27.6%
- Departs 08:2552 flights17.7%
- Departs 08:3040 flights13.7%
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 1727 runs level with that at 83.9%. 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 1727 next to BUF to DEN
Every carrier on BUF to DEN combined arrived on time 74.0% of the time across 573 flights, so UA 1727 is 10 points ahead of it. Across its whole network United Airlines managed 78.8%, which this flight beats by 5 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 1727thin sample | 293 | 83.9% | 67 min | 0.00% | B+ |
| All United Airlines on BUF–DENthin sample | 293 | 83.9% | 67 min | 0.00% | B+ |
| All carriers on BUF–DEN | 573 | 74.0% | 55 min | 0.17% | C+ |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 1727 quarter by quarter
UA 1727 did not run the same all year. Its best quarter was Jul–Sep 2026 at 90.2% on time and its weakest Jan–Mar 2026 at 66.7%, a swing of 24 points on roughly 59 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 flights90.0%
- Oct–Dec 202562 flights85.5%
- Jan–Mar 202648 flights66.7%
- Apr–Jun 202691 flights85.7%
- Jul–Sep 202662 flights90.2%
Scale runs 60% to 95%.
By weekday, UA 1727 did best on Thursday at 92.9% on time and worst on Tuesday at 73.2%. Each day rests on about 42 flights, so a gap of 20 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 1727 runs when it is late
The 47 late arrivals split 23 under half an hour, 8 between 30 and 60 minutes, and 16 an hour or more.
- 15+ min early57 flights19.5%
- Within 15 min188 flights64.4%
- 15–29 min late23 flights7.9%
- 30–59 min late8 flights2.7%
- 1–2 hours late8 flights2.7%
- 2+ hours late8 flights2.7%
Scale runs 0% to 100%.
Share of 292 completed flights by arrival against schedule.
10 of 38 late departures made up the time and arrived on time, 26% of them. In the other direction, 19 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at DEN.
The worst days
Worst days for UA 1727
The latest arrival of the period was on 21 March 2026, 7 hours 15 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 21 March 2026 | 7 hours 15 minutes | Late-arriving aircraft |
| 26 May 2026 | 5 hours 17 minutes | Late-arriving aircraft |
| 17 April 2026 | 4 hours 15 minutes | Carrier |
| 18 February 2026 | 3 hours | Late-arriving aircraft |
| 20 March 2026 | 2 hours 37 minutes | Carrier |
Delay causes
Why UA 1727 runs late
Carrier accounts for 49% of the 3,128 delay minutes carriers reported here, and the remaining four split what is left.
- 49%Carrier
- 28%Late-arriving aircraft
- 18%National Airspace System
- 4%Extreme weather
The largest share of delay minutes, 49%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,540 of the 3,128 delay minutes reported here. The split is drawn from 3,128 delay minutes reported on UA 1727.
Cancellations are rare at 0.00%, below the national 1.89% and low enough to earn the plus on the grade. Almost no flights are called off; the risk here is arriving late, not not arriving.
Connections and routes
What a delay on this flight costs
5.5% 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 about an hour, which a normal layover absorbs.
The 1,359 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 three other city pairs in the data, including JAC to DEN (37), EWR to CLE (19) and IAH to BWI (16), but none flew often enough under UA 1727 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to BUF to DEN only.
One caution: this is a thin sample. 293 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 1727
For a booking, read UA 1727 as 83.9% on time with 0.00% cancelled over 293 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- 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
- Worst months to fly in the US, ranked by the data
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.