Flight number record

UA 1783

United Airlines · Los Angeles to Boston

Route: LAX → BOS
Departs: 08:20
Flights: 365
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s UA 1783, check with United Airlines.

UA 1783 lands a B+, 6 points better than the national rate of 77.6%. About one flight in six arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That is a workable record, not a spotless one. That rests on 365 flights, with a median arrival 12 minutes early.

Set against the rest of the country, UA 1783's record is 6 points better than the US average of 77.6%. That gap is worth roughly 58 fewer late arrivals for every thousand flights.

On time

83.4%

Arrivals under 15 minutes late, of 361 completed flights

Avg delay

85 min

Across delayed arrivals only, not all flights

Cancelled

0.82%

National rate is 1.81%

1 hour+ late

6.6%

National rate is 8.1%

These figures cover 365 flights between July 2025 and June 2026. The median arrival is 12 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.

Schedule

When UA 1783 flies

UA 1783 flies LAX to BOS without a single fixed slot. Its most common scheduled departure was 08:20, used on 93 of 365 flights, with 08:35 (87 flights) and 08:15 (80 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 08:2093 flights25.5%
Departs 08:3587 flights23.8%
Departs 08:1580 flights21.9%

Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.

Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.

A 08:20 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 84.1%, and UA 1783 runs level with that at 83.4%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

Against the route

UA 1783 next to LAX to BOS

Every carrier on LAX to BOS combined arrived on time 78.4% of the time across 4,718 flights, so UA 1783 is 5 points ahead of it. United flew 716 flights on the same city pair under all its flight numbers, including this one, and those ran 87.0% on time. Across its whole network United Airlines managed 79.0%, which this flight beats by 4 points.

UA 1783 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
UA 1783	365	83.4%	85 min	0.82%	B+
All United Airlines on LAX–BOS	716	87.0%	70 min	1.12%	A
All carriers on LAX–BOS	4,718	78.4%	81 min	1.42%	B
United Airlines, whole network	821,041	79.0%	72 min	1.01%	B

Across the year

UA 1783 quarter by quarter

UA 1783 did not run the same all year. Its best quarter was Jan–Mar 2026 at 92.0% on time and its weakest Jul–Sep 2025 at 73.9%, a swing of 18 points on roughly 91 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 202592 flights73.9%
Oct–Dec 202592 flights81.3%
Jan–Mar 202690 flights92.0%
Apr–Jun 202691 flights86.8%

Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.

By weekday, UA 1783 did best on Saturday at 90.4% on time and worst on Sunday at 76.5%. Each day rests on about 52 flights, so a gap of 14 points is worth noticing but could still narrow in another year.

Delay causes

Why UA 1783 runs late

One category carries most of the weight here. National Airspace System accounts for 58% of the 5,114 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.

National Airspace System
58%
Late-arriving aircraft
33%
Carrier
8%
Extreme weather
1%

58% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 2,991 minutes out of 5,114, against a national NAS share of 21%. The split is drawn from 5,114 delay minutes reported on UA 1783.

Cancellations are rare at 0.82%, below the national 1.81% 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

6.6% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last an hour and a half, which a normal layover absorbs.

At 2,611 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 three other city pairs in the data, including BOS to EWR (33), BOS to ORD (12) and DEN to LAX (11), but none flew often enough under UA 1783 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to LAX to BOS only.

One caution: this is a thin sample. 365 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 1783

For a booking, read UA 1783 as 83.4% on time with 0.82% cancelled over 365 flights. Those are rates from the past twelve months, not a forecast for any particular day.

Where to go next

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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures