Flight profile · United Airlines
UA1734
Boston (BOS) to Washington (IAD) · scheduled 5:30 AM – 7:04 AM
How UA1734 performs
623 operations, October 2024 – July 2026.
UA1734 arrived on time 96.1% of the time, against 83.4% for all BOS → IAD flights, so this departure is 12.7 percentage points better than the route as a whole. Against United Airlines’ own flights on this route it is 12.6 points better.
Source: US DOT Bureau of Transportation Statistics · 623 operations, October 2024 – July 2026 · If UA1734 is cancelled or significantly changed, DOT’s automatic refund rule may entitle you to your money back. The refund checker walks through eligibility.
What stands out
How UA1734 compares to other flight numbers, not just to itself.
This flight stays close to typical even on its worst days, a smaller gap than 99% of 11,788 comparable flight numbers.
A typical arrival is 12 min early, and the worst tenth are only 13 minutes worse than that.
Source: FlyerIntel analysis of US DOT BTS data · October 2024 – July 2026 · The one thing about this specific departure that ranks most extreme against every other published flight number, out of everything FlyerIntel checks — shown only when something clears a real statistical bar, not for every flight.
Where UA1734 is right now
A live reading, only if you ask for it. It is not part of the reliability record above.
Ask for the position of UA1734 right now, if receivers on the ground are hearing it. Nothing is requested until you press the button.
Against the rest of the route
| Flight or route | On time | Cancelled | Median delay | Severe | Flights |
|---|---|---|---|---|---|
| UA1734 | 96.1% | 1.77% | -12 min | 0.8% | 623 |
| United Airlines on BOS → IAD | 83.5% | 1.35% | -9 min | 6.2% | 4,586 |
| All BOS → IAD flights | 83.4% | 1.50% | -9 min | 6.3% | 4,652 |
Source: FlyerIntel analysis of US DOT BTS data · October 2024 – July 2026
Why UA1734 runs late
Where US DOT attributed the delay minutes on this flight.
crew, maintenance, boarding and fueling, all within the carrier’s control
airspace and airport capacity, including weather-driven flow control
weather severe enough to stop this flight specifically
Share of the delay minutes US DOT attributed to each cause for UA1734 on BOS → IAD. Only delays of 15 minutes or more are attributed.
Source: US DOT Bureau of Transportation Statistics · Data covering October 2024 – July 2026
Does a late aircraft delay this flight?
How often the plane that flies UA1734 comes in late, and what that does to the departure.
When the aircraft came in 15 or more minutes late, UA1734 pushed back an average of 0 minutes early; when it came in on time or early, an average of 3 minutes early.
Each departure is matched to the flight the same aircraft flew into BOS just before it, using the tail number in the DOT file, 601 of 612 departures in all. A departure is left out when that flight is unknown, was cancelled or diverted, or the aircraft had sat for more than 12 hours. A flight the airline cancelled never left and is not in the count, and one flown by a substitute aircraft is matched to the aircraft that flew it, not to the one first planned.
Against the network at the same turn length
| Share of departures | Inbound landed 15+ late | Left 15+ late after a late inbound | Left 15+ late after an on-time inbound |
|---|---|---|---|
| UA1734 | 24% | 6% | 2% |
| Network, same turn | 33% | 24% | 11% |
The schedule leaves a long gap on the ground, which gives a late aircraft room to catch up before this flight pushes back.
The network row is every flight with a scheduled turn of 3 to 6 hours. How often UA1734’s aircraft landed 15 or more minutes late is lower than the network’s and, once the aircraft was late, how often UA1734 left 15 or more minutes late is lower than the network’s.
More: Which Flight Numbers Pay for a Late Aircraft lists the flight numbers that pass a late aircraft on.
Source: US DOT Bureau of Transportation Statistics · Data covering October 2024 – July 2026
From pushback to gate
When it leaves BOS late, does that still matter by the time it reaches IAD?
UA1734 pushes back an average of 2.4 minutes early and reaches the gate at IAD an average of 9.7 minutes early. The 7.2 minutes between those two figures are slack the published schedule already carries, which is why a late pushback on this flight does not reliably become a late arrival. It spends 15.0 minutes on the taxiways at BOS, 1.6 minutes shorter than a typical BOS departure in the same hour.
On arrival at IAD, UA1734 spends 5.8 min taxiing from touchdown to the gate — ground time a connecting passenger sits through before they can even leave the aircraft, on top of however late the flight itself ran. That is 1.7 minutes shorter than a typical IAD arrival (7.5 min).
Departure delay is averaged over every pushback and arrival delay over every completed arrival, so the two counts differ by the flights that never reached IAD. Taxi-out is gate to wheels up and sits inside the scheduled block rather than on top of it; the comparison is 14,514 departures from BOS scheduled in the clock hour UA1734 most often leaves in. Taxi-in is landing to gate, compared against every arrival FlyerIntel has on file at IAD (169,930 flights), not just UA1734’s own. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · October 2024 – July 2026
The hour it leaves BOS
Part of any flight’s record belongs to the clock rather than to the flight. UA1734 has one departure time, so this is what that time is worth.
On-time arrival rate. 14,514 departures from BOS are scheduled in the 5 AM–6 AM hour over the period, against 440,893 across the whole day.
UA1734 is scheduled out of BOS at 5:30 AM, in the 5 AM–6 AM bank. Departures from BOS in that hour arrive on time 92.0% of the time against 77.2% across the airport’s whole day — the slot alone is worth 14.8 points better before anything about this particular flight is considered.
The two airport figures cover every departure from BOS to every destination, so they describe the slot rather than this journey — the like-for-like comparison against the route is above. Hours are scheduled local, and a number whose schedule moved between banks inside the period has no single hour and is not described here at all. Why the hour matters.
Source: FlyerIntel analysis of US DOT BTS data · October 2024 – July 2026 · Hours below 120 departures are not scored.
Other routes UA1734 has flown
A flight number is a slot in a schedule, and carriers reassign it. These are the other city pairs this number served in the analysis period.
| Route | Operated | Flights | On time |
|---|---|---|---|
| IAD→LAX Washington to Los Angeles | May 22, 2025 – July 31, 2026 | 194 | 85.3% |
| IAD→AUS Washington to Austin | May 24, 2026 – June 24, 2026 | 15 | — |
| IAD→PIT Washington to Pittsburgh | September 25, 2025 – December 1, 2025 | 52 | — |
| IAD→BZN Washington to Bozeman | September 6–21, 2025 | 6 | — |
| IAD→SEA Washington to Seattle | June 26, 2025 – July 31, 2025 | 35 | — |
| IAD→ATL Washington to Atlanta | June 1–25, 2025 | 25 | — |
| IAD→ORD Washington to Chicago | March 7, 2024 – March 29, 2025 | 48 | — |
| IAD→MSP Washington to Minneapolis | December 5–12, 2024 | 2 | — |
| SAN→SFO San Diego to San Francisco | August 1, 2023 – October 26, 2024 | 277 | 64.6% |
| FAT→ORD Fresno to Chicago | June 27, 2024 – August 18, 2024 | 52 | — |
| IAH→IAD Houston to Washington | May 2–22, 2024 | 21 | — |
| LAX→DEN Los Angeles to Denver | March 31, 2024 – May 1, 2024 | 32 | — |
| LGA→IAH New York to Houston | July 2, 2023 – March 6, 2024 | 52 | — |
| SFO→CLE San Francisco to Cleveland | November 28, 2023 – December 20, 2023 | 23 | — |
| AUS→IAH Austin to Houston | November 26, 2023 | 1 | — |
| MIA→SFO Miami to San Francisco | September 30, 2023 – October 28, 2023 | 13 | — |
| LAX→LAS Los Angeles to Las Vegas | September 4, 2023 | 1 | — |
Because the same number has served different journeys, the statistics above describe only the route UA1734 currently operates. Blending them would produce an average of two different flights.
When it goes wrong
The average describes a usual day. This is the day that ruins a connection.
1 min late
against a median of 12 min early
Percentiles over 623 operations; cancelled and diverted flights are counted separately.
Source: US DOT Bureau of Transportation Statistics · Data covering October 2024 – July 2026
Other flights on this route
Same airports, same journey, different odds of arriving on time.
| Flight | Airline | On time | Median arrival | Operations |
|---|---|---|---|---|
| UA1734 this flight | United Airlines | 96.1% | 12 min early | 623 |
| UA2098 | United Airlines | 90.0% | 10 min early | 726 |
| UA721 | United Airlines | 74.0% | 0 min early | 672 |
| UA2136 | United Airlines | 71.5% | 3 min early | 1,088 |
Every departure listed carries at least 600 operations, so the comparison is between figures that mean something. UA1734 is placed in the same ordering rather than left out of it; the rows around it are the most punctual departures on the route, not all of them, so this is a comparison and not a rank. Schedules change; confirm the departure still operates before booking around this.
Data and methodology
Calculated by FlyerIntel from 623 records of UA1734 operating BOS → IAD, published by the US DOT Bureau of Transportation Statistics. A flight counts as delayed when it arrives 15 or more minutes after schedule. Cancelled and diverted flights are excluded from the on-time rate and reported separately. Flight numbers are resolved as carrier plus number plus route, because the same number serves different routes over time.
Full methodology · Data sources · Report a problem
Related research: Most and Least Reliable Flight Numbers · The Delay You Inherit · Making Up Time in the Air
Analysis last recomputed