Flight number record

UA 1015

United Airlines · Boston to Chicago

Route: BOS → ORD
Departs: 18:23
Flights: 305
Period: September 2025 to August 2026

Historical statistics for September 2025 to August 2026, not live status. For today’s UA 1015, check with United Airlines.

UA 1015 earns an F−, which is as low as this site's scale goes for a reason. Only 50.3% of flights arrive inside the 15-minute window, 27 points worse than the national rate of 77.3%. Late arrivals average an hour and a half. Treat any tight connection here as a coin flip. That rests on 305 flights, with a median arrival 14 minutes late.

The national on-time rate over the same period is 77.3%, so UA 1015 runs 27 points behind the country as a whole. Across a thousand flights that is about 270 extra late arrivals.

On time

50.3%

Arrivals under 15 minutes late, of 292 completed flights

Avg delay

86 min

Across delayed arrivals only, not all flights

Cancelled

4.26%

National rate is 1.89%

1 hour+ late

24.3%

National rate is 8.3%

These figures cover 305 flights between September 2025 and August 2026. Beyond the headline rate, 24.3% of arrivals land a full hour or more behind schedule, against 8.3% nationally.

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Schedule

When UA 1015 flies

UA 1015 flies BOS to ORD without a single fixed slot. Its most common scheduled departure was 18:23, used on 76 of 305 flights, with 18:43 (47 flights) and 18:40 (33 flights) next.

Departs 18:2376 flights24.9%
Departs 18:4347 flights15.4%
Departs 18:4033 flights10.8%

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 18:23 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.0%, and UA 1015 runs 18 points worse at 50.3%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.

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Against the route

UA 1015 next to BOS to ORD

Every carrier on BOS to ORD combined arrived on time 71.9% of the time across 7,860 flights, so UA 1015 is 22 points behind it. United flew 2,791 flights on the same city pair under all its flight numbers, including this one, and those ran 74.5% on time. Across its whole network United Airlines managed 78.8%, which this flight trails by 29 points.

UA 1015 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
UA 1015thin sample	305	50.3%	86 min	4.26%	F−
All United Airlines on BOS–ORD	2,791	74.5%	86 min	1.79%	C
All carriers on BOS–ORD	7,860	71.9%	87 min	2.98%	C
United Airlines, whole network	830,825	78.8%	73 min	1.02%	B

Across the year

UA 1015 quarter by quarter

UA 1015 did not run the same all year. Its best quarter was Apr–Jun 2026 at 59.5% on time and its weakest Jul–Sep 2026 at 41.4%, a swing of 18 points on roughly 76 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 202527 flights—
Oct–Dec 202589 flights48.2%
Jan–Mar 202653 flights57.1%
Apr–Jun 202675 flights59.5%
Jul–Sep 202661 flights41.4%

Scale runs 35% to 65%. Rows with fewer than 30 flights show a dash.

By weekday, UA 1015 did best on Wednesday at 56.2% on time and worst on Sunday at 42.9%. 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 1015 runs when it is late

The 145 late arrivals split 34 under half an hour, 40 between 30 and 60 minutes, and 71 an hour or more.

15+ min early18 flights6.2%
Within 15 min129 flights44.2%
15–29 min late34 flights11.6%
30–59 min late40 flights13.7%
1–2 hours late38 flights13.0%
2+ hours late33 flights11.3%

Scale runs 0% to 100%.

Share of 292 completed flights by arrival against schedule.

Time lost at the gate mostly stays lost. Of 123 departures that left 15 minutes late or more, only 10 made it up before arrival. In the other direction, 32 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at ORD.

The worst days

Worst days for UA 1015

The latest arrival of the period was on 25 September 2025, 7 hours 30 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The five worst days are spread across September, June, April and December, with no single month standing out.

The latest arrivals of UA 1015 in the period
Date	Arrived late by	Largest filed cause
25 September 2025	7 hours 30 minutes	Late-arriving aircraft
10 June 2026	6 hours 6 minutes	National Airspace System
27 April 2026	6 hours 3 minutes	National Airspace System
17 June 2026	4 hours 39 minutes	Carrier
29 December 2025	4 hours 24 minutes	Late-arriving aircraft

Delay causes

Why UA 1015 runs late

Late-arriving aircraft accounts for 55% of the 12,000 delay minutes carriers reported here, and the remaining four split what is left.

Late-arriving aircraft
55%
National Airspace System
34%
Carrier
10%
Extreme weather
1%

55% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 12,000 reported delay minutes here, that single category outweighs weather by 55 to one. The split is drawn from 12,466 delay minutes reported on UA 1015.

Cancellations run at 4.26%, against 1.89% nationally. That is about one flight in 25 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.

Connections and routes

What a delay on this flight costs

24.3% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.

The 867 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.

The same number turns up on ten other city pairs in the data, including SFO to BOS (83), ORD to IAD (35) and ORD to DEN (16), but none flew often enough under UA 1015 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to BOS to ORD only.

One caution: this is a thin sample. 305 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 1015

For a booking, the cancellation rate is the figure to plan around on UA 1015: 4.26% of its 305 scheduled flights did not operate. A late arrival costs an hour and a half, but a cancellation costs the day, so leave a later option open.

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, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures