Flight number record

UA 668

United Airlines · San Juan to Houston

Route: SJU → IAH
Departs: 14:55
Flights: 365
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s UA 668, check with United Airlines.

UA 668 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 365 flights, with a median arrival 7 minutes early.

On time

80.9%

Arrivals under 15 minutes late, of 362 completed flights

Avg delay

49 min

Across delayed arrivals only, not all flights

Cancelled

0.55%

National rate is 1.81%

1 hour+ late

3.9%

National rate is 8.1%

These figures cover 365 flights between July 2025 and June 2026. The median arrival is 7 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 668 flies

UA 668 flies SJU to IAH without a single fixed slot. Its most common scheduled departure was 14:55, used on 196 of 365 flights, with 15:46 (126 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 14:55196 flights53.7%
Departs 15:46126 flights34.5%

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 14:55 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 72.4%, and UA 668 runs 9 points better at 80.9%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

UA 668 next to SJU to IAH

Every carrier on SJU to IAH combined arrived on time 87.7% of the time across 948 flights, so UA 668 is 7 points behind it. United flew 872 flights on the same city pair under all its flight numbers, including this one, and those ran 88.9% on time. Across its whole network United Airlines managed 79.0%, which this flight beats by 2 points.

UA 668 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
UA 668	365	80.9%	49 min	0.55%	B+
All United Airlines on SJU–IAH	872	88.9%	52 min	0.57%	A+
All carriers on SJU–IAH	948	87.7%	55 min	0.63%	A+
United Airlines, whole network	821,041	79.0%	72 min	1.01%	B

Across the year

UA 668 quarter by quarter

UA 668 did not run the same all year. Its best quarter was Jul–Sep 2025 at 89.0% on time and its weakest Oct–Dec 2025 at 72.8%, a swing of 16 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 flights89.0%
Oct–Dec 202592 flights72.8%
Jan–Mar 202690 flights80.7%
Apr–Jun 202691 flights81.3%

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

By weekday, UA 668 did best on Tuesday at 86.8% on time and worst on Sunday at 74.5%. Each day rests on about 52 flights, so a gap of 12 points is worth noticing but could still narrow in another year.

Delay causes

Why UA 668 runs late

One category carries most of the weight here. Late-arriving aircraft accounts for 58% of the 3,404 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.

Late-arriving aircraft
58%
National Airspace System
30%
Carrier
12%

58% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 3,404 reported delay minutes here, that single category outweighs weather by 58 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 3,404 delay minutes reported on UA 668.

Cancellations are rare at 0.55%, 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 3.9% 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 2,007 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.

Every one of the 365 flights under UA 668 in the data flew SJU to IAH. The number was not reused on any other city pair, which makes this a clean record of one route.

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 668

For a booking, UA 668 is one of the weaker ways to fly SJU to IAH: 7 points below the route as a whole. If the schedule allows, compare it with the other departures listed on the route page before settling on this one.

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