Flight profile · United Airlines
UA1783
Los Angeles (LAX) to Boston (BOS) · scheduled 8:20 AM – 4:53 PM
How UA1783 performs
765 operations, June 2024 – July 2026.
UA1783 arrived on time 83.8% of the time, against 80.2% for all LAX → BOS flights, so this departure is 3.6 percentage points better than the route as a whole. Against United Airlines’ own flights on this route it is 3.3 points worse.
Source: US DOT Bureau of Transportation Statistics · 765 operations, June 2024 – July 2026 · If UA1783 is cancelled or significantly changed, DOT’s automatic refund rule may entitle you to your money back. The refund checker walks through eligibility.
Where UA1783 is right now
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Against the rest of the route
| Flight or route | On time | Cancelled | Median delay | Severe | Flights |
|---|---|---|---|---|---|
| UA1783 | 83.8% | 0.39% | -12 min | 5.9% | 765 |
| United Airlines on LAX → BOS | 87.1% | 0.82% | -12 min | 4.3% | 2,305 |
| All LAX → BOS flights | 80.2% | 0.82% | -8 min | 7.4% | 14,323 |
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026
Why UA1783 runs late
Where US DOT attributed the delay minutes on this flight.
airspace and airport capacity, including weather-driven flow control
the inbound aircraft was late, so this flight started late
crew, maintenance, boarding and fueling, all within the carrier’s control
weather severe enough to stop this flight specifically
Share of the delay minutes US DOT attributed to each cause for UA1783 on LAX → BOS. Only delays of 15 minutes or more are attributed.
Source: US DOT Bureau of Transportation Statistics · Data covering June 2024 – July 2026
Does a late aircraft delay this flight?
How often the plane that flies UA1783 comes in late, and what that does to the departure.
UA1783 is usually the aircraft’s first flight of the day: the schedule gives it a median of 8.4 hours on the ground at LAX, so its “inbound” is mostly the aircraft’s arrival the evening before.
The aircraft flying UA1783 came in 15 or more minutes late on 19% of the departures where its previous flight is known. There are not enough departures in both groups to say how the flight left after a late one and after an on-time one.
Each departure is matched to the flight the same aircraft flew into LAX just before it, using the tail number in the DOT file, 423 of 762 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 |
|---|---|
| UA1783 | 19% |
| Network, same turn | 29% |
A night on the ground absorbs most of a late arrival, so a late inbound matters far less on a turn this long than on a same-day one.
The network row is every flight with a scheduled turn of 6 hours or more, usually overnight. How often UA1783’s aircraft landed 15 or more minutes late is lower than the network’s. There are not enough departures in both groups to compare how it left.
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 June 2024 – July 2026
From pushback to gate
When it leaves LAX late, does that still matter by the time it reaches BOS?
UA1783 pushes back an average of 8.9 minutes late and reaches the gate at BOS an average of 0.7 minutes early. The 9.5 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 22.4 minutes on the taxiways at LAX, 1.6 minutes longer than a typical LAX departure in the same hour.
On arrival at BOS, UA1783 spends 6.7 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 2.3 minutes shorter than a typical BOS arrival (9.0 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 BOS. Taxi-out is gate to wheels up and sits inside the scheduled block rather than on top of it; the comparison is 55,525 departures from LAX scheduled in the clock hour UA1783 most often leaves in. Taxi-in is landing to gate, compared against every arrival FlyerIntel has on file at BOS (440,886 flights), not just UA1783’s own. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026
The hour it leaves LAX
Part of any flight’s record belongs to the clock rather than to the flight. UA1783 has one departure time, so this is what that time is worth.
On-time arrival rate. 55,525 departures from LAX are scheduled in the 8 AM–9 AM hour over the period, against 595,153 across the whole day.
UA1783 is scheduled out of LAX at 8:20 AM, in the 8 AM–9 AM bank. Departures from LAX in that hour arrive on time 84.6% of the time against 81.4% across the airport’s whole day — the slot alone is worth 3.2 points better before anything about this particular flight is considered.
The two airport figures cover every departure from LAX 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 · June 2024 – July 2026 · Hours below 120 departures are not scored.
Other routes UA1783 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 |
|---|---|---|---|
| BOS→ORD Boston to Chicago | July 1, 2023 – May 18, 2026 | 235 | 73.0% |
| BOS→EWR Boston to Newark | December 20, 2024 – December 1, 2025 | 46 | — |
| DEN→LAX Denver to Los Angeles | August 1–18, 2025 | 11 | — |
| EWR→JAX Newark to Jacksonville | May 23, 2024 – June 26, 2024 | 35 | — |
| IAH→SAN Houston to San Diego | May 2–22, 2024 | 21 | — |
| LAX→IAH Los Angeles to Houston | March 31, 2024 – May 1, 2024 | 32 | — |
| PIT→IAD Pittsburgh to Washington | March 8–30, 2024 | 23 | — |
| JAX→IAD Jacksonville to Washington | March 7, 2024 | 1 | — |
| ORD→SAN Chicago to San Diego | December 21, 2023 – March 4, 2024 | 34 | — |
| ORD→IAH Chicago to Houston | July 1, 2023 – November 27, 2023 | 104 | 69.6% |
| EWR→BOS Newark to Boston | October 29, 2023 – November 27, 2023 | 28 | — |
Because the same number has served different journeys, the statistics above describe only the route UA1783 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.
35 min late
against a median of 12 min early
Percentiles over 765 operations; cancelled and diverted flights are counted separately.
Source: US DOT Bureau of Transportation Statistics · Data covering June 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 |
|---|---|---|---|---|
| UA2210 | United Airlines | 88.9% | 12 min early | 765 |
| AA2453 | American Airlines | 84.5% | 8 min early | 1,021 |
| UA1783 this flight | United Airlines | 83.8% | 12 min early | 765 |
| DL507 | Delta Air Lines | 81.4% | 6 min early | 684 |
| B6288 | JetBlue | 80.9% | 10 min early | 1,052 |
| B6188 | JetBlue | 75.1% | 6 min early | 606 |
| DL437 | Delta Air Lines | 74.9% | 4 min early | 679 |
| B6988 | JetBlue | 74.7% | 8 min early | 987 |
| B61388 | JetBlue | 69.1% | 3 min early | 648 |
Every departure listed carries at least 600 operations, so the comparison is between figures that mean something. UA1783 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 765 records of UA1783 operating LAX → BOS, 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
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