Flight number record
UA 1734
United Airlines · Boston to Washington
- Route
- BOS → IAD
- Departs
- 05:45
- Flights
- 345
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 1734, check with United Airlines.
UA 1734 earns an A. Nearly every flight arrives inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 19 points better than the national rate of 77.3%. When something does go wrong the average delay runs roughly 50 minutes. That rests on 345 flights, with a median arrival 13 minutes early.
Set against the rest of the country, UA 1734's record is 19 points better than the US average of 77.3%. That gap is worth roughly 188 fewer late arrivals for every thousand flights.
Key figures
On time
96.1%
Arrivals under 15 minutes late, of 337 completed flights
Avg delay
49 min
Across delayed arrivals only, not all flights
Cancelled
2.32%
National rate is 1.89%
1 hour+ late
0.6%
National rate is 8.3%
These figures cover 345 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 1734 flies
UA 1734 flies BOS to IAD without a single fixed slot. Its most common scheduled departure was 05:45, used on 196 of 345 flights, with 05:30 (110 flights) next.
- Departs 05:45196 flights56.8%
- Departs 05:30110 flights31.9%
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 05:45 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and UA 1734 runs 7 points better at 96.1%. 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 1734 next to BOS to IAD
Every carrier on BOS to IAD combined arrived on time 83.2% of the time across 1,527 flights, so UA 1734 is 13 points ahead of it. United flew 1,450 flights on the same city pair under all its flight numbers, including this one, and those ran 83.3% on time. Across its whole network United Airlines managed 78.8%, which this flight beats by 17 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 1734thin sample | 345 | 96.1% | 49 min | 2.32% | A |
| All United Airlines on BOS–IAD | 1,450 | 83.3% | 78 min | 2.28% | B |
| All carriers on BOS–IAD | 1,527 | 83.2% | 85 min | 3.01% | B− |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 1734 quarter by quarter
Quarter by quarter UA 1734 held fairly steady: 100.0% in Jul–Sep 2025, 95.7% in Oct–Dec 2025, 92.3% in Jan–Mar 2026, 98.9% in Apr–Jun 2026 and 95.0% in Jul–Sep 2026. A spread of 8 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Jul–Sep 202530 flights100.0%
- Oct–Dec 202592 flights95.7%
- Jan–Mar 202670 flights92.3%
- Apr–Jun 202691 flights98.9%
- Jul–Sep 202662 flights95.0%
Scale runs 85% to 100%.
By weekday, UA 1734 ranged from 89.4% on Saturday to 100.0% on Tuesday. With about 49 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.
Arrival by arrival
How late UA 1734 runs when it is late
UA 1734 often beats the schedule: 140 of 337 completed flights, 42%, arrived 15 minutes or more early. Most of the lateness is short. 8 of the 13 late arrivals were under half an hour behind, and 2 reached an hour or more.
- 15+ min early140 flights41.5%
- Within 15 min184 flights54.6%
- 15–29 min late8 flights2.4%
- 30–59 min late3 flights0.9%
- 1–2 hours late1 flights0.3%
- 2+ hours late1 flights0.3%
Scale runs 0% to 100%.
Share of 337 completed flights by arrival against schedule.
Only 12 of 337 completed flights left 15 minutes late or more, too few to say how often the time is made up.
The worst days
Worst days for UA 1734
The latest arrival of the period was on 25 October 2025, 4 hours 31 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). Three of the five worst days fell in February 2026.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 25 October 2025 | 4 hours 31 minutes | Carrier |
| 25 February 2026 | 1 hour 23 minutes | Carrier |
| 27 December 2025 | 57 minutes | National Airspace System |
| 18 February 2026 | 34 minutes | Carrier |
| 21 February 2026 | 33 minutes | National Airspace System |
Delay causes
Why UA 1734 runs late
Carrier accounts for 74% of the 636 delay minutes carriers reported here, and the remaining four split what is left.
- 74%Carrier
- 21%National Airspace System
- 5%Extreme weather
The largest share of delay minutes, 74%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 471 of the 636 delay minutes reported here. The split is drawn from 636 delay minutes reported on UA 1734.
Cancellations sit at 2.32% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
Badly late arrivals are rare here: only 0.6% 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.
The same number turns up on four other city pairs in the data, including IAD to LAX (203), IAD to PIT (52) and IAD to AUS (15), but none flew often enough under UA 1734 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to BOS to IAD only.
One caution: this is a thin sample. 345 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 1734
For a booking, read UA 1734 as 96.1% on time with 2.32% cancelled over 345 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- BOS to IAD, every carrier and departure
- IAD to BOS, the return direction
- United Airlines 721 on the same route76.6%
- United Airlines 2098 on the same route89.7%
- United Airlines 2136 on the same route70.0%
- Boston Logan International (BOS) delay statistics
- Washington Dulles International (IAD) delay statistics
- United Airlines on-time record
- Every United Airlines flight number with a record
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- 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.