Flight number record
DL 1421
Delta Air Lines · San Francisco to Los Angeles
- Route
- SFO → LAX
- Departs
- 08:55
- Flights
- 352
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 1421, check with Delta Air Lines.
DL 1421 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 12 points better than the national rate of 77.3%. When something does go wrong the average delay runs about an hour. That rests on 352 flights, with a median arrival 11 minutes early.
Set against the rest of the country, DL 1421's record is 12 points better than the US average of 77.3%. That gap is worth roughly 124 fewer late arrivals for every thousand flights.
Key figures
On time
89.7%
Arrivals under 15 minutes late, of 339 completed flights
Avg delay
68 min
Across delayed arrivals only, not all flights
Cancelled
3.69%
National rate is 1.89%
1 hour+ late
3.5%
National rate is 8.3%
These figures cover 352 flights between September 2025 and August 2026. The median arrival is 11 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 DL 1421 flies
DL 1421 flies SFO to LAX without a single fixed slot. Its most common scheduled departure was 08:55, used on 87 of 352 flights, with 08:25 (62 flights) and 09:30 (60 flights) next.
- Departs 08:5587 flights24.7%
- Departs 08:2562 flights17.6%
- Departs 09:3060 flights17.0%
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 08:55 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 83.9%, and DL 1421 runs 6 points better at 89.7%. 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
DL 1421 next to SFO to LAX
Every carrier on SFO to LAX combined arrived on time 70.9% of the time across 11,437 flights, so DL 1421 is 19 points ahead of it. Delta flew 2,373 flights on the same city pair under all its flight numbers, including this one, and those ran 69.8% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight beats by 9 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 1421thin sample | 352 | 89.7% | 68 min | 3.69% | A− |
| All Delta Air Lines on SFO–LAX | 2,373 | 69.8% | 63 min | 1.56% | C |
| All carriers on SFO–LAX | 11,437 | 70.9% | 58 min | 0.82% | C+ |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 1421 quarter by quarter
DL 1421 did not run the same all year. Its best quarter was Jul–Sep 2025 at 96.7% on time and its weakest Apr–Jun 2026 at 86.0%, a swing of 11 points on roughly 70 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 202530 flights96.7%
- Oct–Dec 202591 flights89.8%
- Jan–Mar 202681 flights90.7%
- Apr–Jun 202688 flights86.0%
- Jul–Sep 202662 flights90.0%
Scale runs 80% to 100%.
By weekday, DL 1421 did best on Monday at 94.1% on time and worst on Friday at 81.6%. Each day rests on about 50 flights, so a gap of 13 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 1421 runs when it is late
DL 1421 often beats the schedule: 132 of 339 completed flights, 39%, arrived 15 minutes or more early. The 35 late arrivals split 15 under half an hour, 8 between 30 and 60 minutes, and 12 an hour or more.
- 15+ min early132 flights38.9%
- Within 15 min172 flights50.7%
- 15–29 min late15 flights4.4%
- 30–59 min late8 flights2.4%
- 1–2 hours late6 flights1.8%
- 2+ hours late6 flights1.8%
Scale runs 0% to 100%.
Share of 339 completed flights by arrival against schedule.
6 of 28 late departures made up the time and arrived on time, 21% of them. 13 flights left on time and still arrived late.
The worst days
Worst days for DL 1421
The latest arrival of the period was on 20 December 2025, 5 hours 57 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 20 December 2025 | 5 hours 57 minutes | Carrier |
| 2 April 2026 | 4 hours 33 minutes | Carrier |
| 13 November 2025 | 4 hours 1 minute | Carrier |
| 7 November 2025 | 2 hours 22 minutes | Late-arriving aircraft |
| 3 April 2026 | 2 hours 5 minutes | Late-arriving aircraft |
Delay causes
Why DL 1421 runs late
Carrier accounts for 53% of the 2,372 delay minutes carriers reported here, and the remaining four split what is left.
- 53%Carrier
- 27%Late-arriving aircraft
- 20%National Airspace System
The largest share of delay minutes, 53%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,262 of the 2,372 delay minutes reported here. The split is drawn from 2,372 delay minutes reported on DL 1421.
Cancellations run at 3.69%, against 1.89% nationally. That is roughly 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
Badly late arrivals are rare here: only 3.5% 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.
DL 1421 is not only a SFO to LAX flight. It also flew LAX to SFO (352 flights, 94.1% 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. 352 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.
| Also flown as | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| LAX to SFOthin sample | 352 | 94.1% | 52 min | 3.41% | A− |
What to do with this
Booking DL 1421
For a booking, the cancellation rate is the figure to plan around on DL 1421: 3.69% of its 352 scheduled flights did not operate. A late arrival costs about an hour, but a cancellation costs the day, so leave a later option open.
Related
Where to go next
- SFO to LAX, every carrier and departure
- LAX to SFO, the return direction
- Delta Air Lines 1598 on the same route93.4%
- Delta Air Lines 2267 on the same route49.2%
- United Airlines 2179 on the same route68.5%
- United Airlines 1754 on the same route71.8%
- Delta Air Lines 1715 on the same route56.1%
- United Airlines 1164 on the same route73.7%
- San Francisco International (SFO) delay statistics
- Los Angeles International (LAX) delay statistics
- Delta Air Lines on-time record
- Every Delta Air Lines flight number with a record
- The most and least reliable flight numbers in the US
- What a cancellation rate actually tells you (and what it hides)
A flight number here means Delta Air Lines’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 ; recomputed monthly. How this data is collected.