Flight number record

UA 1339

United Airlines · Denver to San Juan

Route: DEN → SJU
Departs: 09:45
Flights: 333
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s UA 1339, check with United Airlines.

UA 1339 lands a B+, 3 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about 50 minutes on average. That is a workable record, not a spotless one. That rests on 333 flights, with a median arrival 3 minutes early.

On time

80.5%

Arrivals under 15 minutes late, of 328 completed flights

Avg delay

50 min

Across delayed arrivals only, not all flights

Cancelled

0.30%

National rate is 1.81%

1 hour+ late

4.0%

National rate is 8.1%

These figures cover 333 flights between July 2025 and June 2026. The median arrival is 3 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 1339 flies

UA 1339 flies DEN to SJU without a single fixed slot. Its most common scheduled departure was 09:45, used on 154 of 333 flights, with 09:43 (143 flights) and 09:50 (36 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 09:45154 flights46.2%
Departs 09:43143 flights42.9%
Departs 09:5036 flights10.8%

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 09:45 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 84.1%, and UA 1339 runs 4 points worse at 80.5%. 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 1339 next to DEN to SJU

Across its whole network United Airlines managed 79.0%, which this flight beats by 2 points.

UA 1339 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
UA 1339thin sample	333	80.5%	50 min	0.30%	B+
All United Airlines on DEN–SJUthin sample	333	80.5%	50 min	0.30%	B+
All carriers on DEN–SJUthin sample	333	80.5%	50 min	0.30%	B+
United Airlines, whole network	821,041	79.0%	72 min	1.01%	B

Across the year

UA 1339 quarter by quarter

UA 1339 did not run the same all year. Its best quarter was Apr–Jun 2026 at 91.2% on time and its weakest Jul–Sep 2025 at 54.2%, a swing of 37 points on roughly 83 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 202560 flights54.2%
Oct–Dec 202592 flights86.8%
Jan–Mar 202690 flights80.5%
Apr–Jun 202691 flights91.2%

Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.

By weekday, UA 1339 did best on Wednesday at 90.9% on time and worst on Saturday at 68.6%. Each day rests on about 48 flights, so a gap of 22 points is worth noticing but could still narrow in another year.

Delay causes

Why UA 1339 runs late

One category carries most of the weight here. National Airspace System accounts for 50% of the 3,207 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
50%
Late-arriving aircraft
25%
Carrier
25%

50% 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 1,604 minutes out of 3,207, against a national NAS share of 21%. The split is drawn from 3,207 delay minutes reported on UA 1339.

Cancellations are rare at 0.30%, 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

Badly late arrivals are rare here: only 4.0% land an hour or more behind schedule, against 8.1% 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.

At 2,733 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.

UA 1339 is not only a DEN to SJU flight. It also flew LAX to DEN (303 flights, 95.7% on time) often enough to be scored on its own. Airlines attach one number to several legs of an aircraft's day, and each leg keeps its own record here, so check which city pair is on your booking before reading a rate.

One caution: this is a thin sample. 333 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.

Other routes flown as UA 1339
Also flown as	Flights	On time	Avg delay	Cancelled	Grade
LAX to DENthin sample	303	95.7%	65 min	0.66%	A+

What to do with this

Booking UA 1339

For a booking, read UA 1339 as 80.5% on time with 0.30% cancelled over 333 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