Flight number record
UA 2156
United Airlines · Washington to Las Vegas
- Route
- IAD → LAS
- Departs
- 12:35
- Flights
- 309
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 2156, check with United Airlines.
UA 2156 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 12 points better than the national rate of 77.3%. When something does go wrong the average delay runs about 50 minutes. That rests on 309 flights, with a median arrival 13 minutes early.
Set against the rest of the country, UA 2156's record is 12 points better than the US average of 77.3%. That gap is worth roughly 120 fewer late arrivals for every thousand flights.
Key figures
On time
89.3%
Arrivals under 15 minutes late, of 307 completed flights
Avg delay
50 min
Across delayed arrivals only, not all flights
Cancelled
0.32%
National rate is 1.89%
1 hour+ late
2.6%
National rate is 8.3%
These figures cover 309 flights between September 2025 and August 2026. The median arrival is 13 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 2156 flies
UA 2156 flies IAD to LAS without a single fixed slot. Its most common scheduled departure was 12:35, used on 53 of 309 flights, with 13:00 (46 flights) and 13:05 (38 flights) next.
- Departs 12:3553 flights17.2%
- Departs 13:0046 flights14.9%
- Departs 13:0538 flights12.3%
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 12:35 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.3%, and UA 2156 runs 11 points better at 89.3%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
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Against the route
UA 2156 next to IAD to LAS
Every carrier on IAD to LAS combined arrived on time 85.3% of the time across 1,069 flights, so UA 2156 is 4 points ahead of it. United flew 965 flights on the same city pair under all its flight numbers, including this one, and those ran 88.0% on time. Across its whole network United Airlines managed 78.8%, which this flight beats by 11 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 2156thin sample | 309 | 89.3% | 50 min | 0.32% | A+ |
| All United Airlines on IAD–LAS | 965 | 88.0% | 80 min | 0.52% | A+ |
| All carriers on IAD–LAS | 1,069 | 85.3% | 71 min | 0.56% | A+ |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 2156 quarter by quarter
Quarter by quarter UA 2156 held fairly steady: 92.5% in Oct–Dec 2025, 88.8% in Jan–Mar 2026, 87.9% in Apr–Jun 2026 and 88.3% in Jul–Sep 2026. A spread of 5 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Oct–Dec 202567 flights92.5%
- Jan–Mar 202690 flights88.8%
- Apr–Jun 202691 flights87.9%
- Jul–Sep 202661 flights88.3%
Scale runs 80% to 100%.
By weekday, UA 2156 did best on Saturday at 95.5% on time and worst on Monday at 82.2%. Each day rests on about 44 flights, so a gap of 13 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 2156 runs when it is late
UA 2156 often beats the schedule: 140 of 307 completed flights, 46%, arrived 15 minutes or more early. The 33 late arrivals split 14 under half an hour, 11 between 30 and 60 minutes, and 8 an hour or more.
- 15+ min early140 flights45.6%
- Within 15 min134 flights43.6%
- 15–29 min late14 flights4.6%
- 30–59 min late11 flights3.6%
- 1–2 hours late5 flights1.6%
- 2+ hours late3 flights1.0%
Scale runs 0% to 100%.
Share of 307 completed flights by arrival against schedule.
A late pushback is often recovered here: of 33 departures that left 15 minutes late or more, 15 still arrived on time. 15 flights left on time and still arrived late.
The worst days
Worst days for UA 2156
The latest arrival of the period was on 29 June 2026, 4 hours 52 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The five worst days are spread across June, August, January and July, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 29 June 2026 | 4 hours 52 minutes | Late-arriving aircraft |
| 21 August 2026 | 2 hours 55 minutes | Late-arriving aircraft |
| 24 August 2026 | 2 hours 30 minutes | Carrier |
| 26 January 2026 | 1 hour 11 minutes | National Airspace System |
| 21 July 2026 | 1 hour 10 minutes | National Airspace System |
Delay causes
Why UA 2156 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 1,644 reported delay minutes.
- 36%Late-arriving aircraft
- 35%Carrier
- 27%National Airspace System
- 2%Extreme weather
36% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 1,644 reported delay minutes here, that single category outweighs weather by 23 to one. The split is drawn from 1,644 delay minutes reported on UA 2156.
Cancellations are rare at 0.32%, 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 routes
What a delay on this flight costs
Badly late arrivals are rare here: only 2.6% 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.
At 2,065 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The same number turns up on six other city pairs in the data, including RSW to IAD (68), MSP to EWR (50) and TPA to IAD (37), but none flew often enough under UA 2156 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to IAD to LAS only.
One caution: this is a thin sample. 309 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 2156
For a booking, UA 2156 has one of the better records a US domestic flight can show: 89.3% on time and 0.32% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- IAD to LAS, every carrier and departure
- LAS to IAD, the return direction
- United Airlines 1323 on the same route95.6%
- Washington Dulles International (IAD) delay statistics
- Harry Reid International (LAS) 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
- Why the first flight of the morning is statistically safest
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.