Flight number record

UA 1678

United Airlines · San Francisco to Washington

Route: SFO → DCA
Departs: 08:20
Flights: 363
Period: September 2025 to August 2026

Historical statistics for September 2025 to August 2026, not live status. For today’s UA 1678, check with United Airlines.

UA 1678 earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 11 points better than the national rate of 77.3%. When something does go wrong the average delay runs roughly 50 minutes. That rests on 363 flights, with a median arrival 14 minutes early.

Set against the rest of the country, UA 1678's record is 11 points better than the US average of 77.3%. That gap is worth roughly 107 fewer late arrivals for every thousand flights.

On time

88.0%

Arrivals under 15 minutes late, of 357 completed flights

Avg delay

48 min

Across delayed arrivals only, not all flights

Cancelled

0.55%

National rate is 1.89%

1 hour+ late

3.1%

National rate is 8.3%

These figures cover 363 flights between September 2025 and August 2026. The median arrival is 14 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.

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Schedule

When UA 1678 flies

UA 1678 flies SFO to DCA without a single fixed slot. Its most common scheduled departure was 08:20, used on 123 of 363 flights, with 08:35 (76 flights) and 08:40 (43 flights) next.

Departs 08:20123 flights33.9%
Departs 08:3576 flights20.9%
Departs 08:4043 flights11.8%

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 08:20 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 83.9%, and UA 1678 runs 4 points better at 88.0%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

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Against the route

UA 1678 next to SFO to DCA

Every carrier on SFO to DCA combined arrived on time 78.4% of the time across 1,090 flights, so UA 1678 is 10 points ahead of it. United flew 727 flights on the same city pair under all its flight numbers, including this one, and those ran 78.4% on time. Across its whole network United Airlines managed 78.8%, which this flight beats by 9 points.

UA 1678 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
UA 1678thin sample	363	88.0%	48 min	0.55%	A+
All United Airlines on SFO–DCA	727	78.4%	58 min	0.55%	B+
All carriers on SFO–DCA	1,090	78.4%	55 min	0.64%	B+
United Airlines, whole network	830,825	78.8%	73 min	1.02%	B

Across the year

UA 1678 quarter by quarter

Quarter by quarter UA 1678 held fairly steady: 91.3% in Oct–Dec 2025, 89.7% in Jan–Mar 2026, 90.0% in Apr–Jun 2026 and 83.3% in Jul–Sep 2026. A spread of 8 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202530 flights—
Oct–Dec 202592 flights91.3%
Jan–Mar 202689 flights89.7%
Apr–Jun 202691 flights90.0%
Jul–Sep 202661 flights83.3%

Scale runs 75% to 95%. Rows with fewer than 30 flights show a dash.

By weekday, UA 1678 did best on Tuesday at 94.2% on time and worst on Friday at 82.0%. Each day rests on about 52 flights, so a gap of 12 points is worth noticing but could still narrow in another year.

Arrival by arrival

How late UA 1678 runs when it is late

UA 1678 often beats the schedule: 177 of 357 completed flights, 50%, arrived 15 minutes or more early. The 43 late arrivals split 19 under half an hour, 13 between 30 and 60 minutes, and 11 an hour or more.

15+ min early177 flights49.6%
Within 15 min137 flights38.4%
15–29 min late19 flights5.3%
30–59 min late13 flights3.6%
1–2 hours late9 flights2.5%
2+ hours late2 flights0.6%

Scale runs 0% to 100%.

Share of 357 completed flights by arrival against schedule.

Time lost at the gate mostly stays lost. Of 22 departures that left 15 minutes late or more, only 2 made it up before arrival. In the other direction, 23 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 DCA.

The worst days

Worst days for UA 1678

The latest arrival of the period was on 9 April 2026, 4 hours 22 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. On three of the five worst days the largest share was filed as national airspace system delay.

The latest arrivals of UA 1678 in the period
Date	Arrived late by	Largest filed cause
9 April 2026	4 hours 22 minutes	Late-arriving aircraft
17 May 2026	2 hours 45 minutes	Late-arriving aircraft
20 August 2026	1 hour 36 minutes	National Airspace System
10 August 2026	1 hour 34 minutes	National Airspace System
12 June 2026	1 hour 30 minutes	National Airspace System

Delay causes

Why UA 1678 runs late

National Airspace System accounts for 68% of the 2,072 delay minutes carriers reported here, and the remaining four split what is left.

National Airspace System
68%
Late-arriving aircraft
23%
Carrier
10%

68% 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 1,403 minutes out of 2,072, against a national NAS share of 21%. The split is drawn from 2,072 delay minutes reported on UA 1678.

Cancellations are rare at 0.55%, below the national 1.89% 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 3.1% land an hour or more behind schedule, against 8.3% 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 2,442 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 two other city pairs in the data, including DCA to IAH (133) and PHX to SFO (78), but none flew often enough under UA 1678 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to SFO to DCA only.

One caution: this is a thin sample. 363 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 1678

For a booking, UA 1678 has one of the better records a US domestic flight can show: 88.0% on time and 0.55% cancelled. That is a base rate, not a promise about any single 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, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures