Flight number record
DL 634
Delta Air Lines · Detroit to Los Angeles
- Route
- DTW → LAX
- Departs
- 12:30
- Flights
- 349
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 634, check with Delta Air Lines.
DL 634 lands a B+, 4 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by roughly 45 minutes on average. That rests on 349 flights, with a median arrival 5 minutes early.
Set against the rest of the country, DL 634's record is 4 points better than the US average of 77.3%. That gap is worth roughly 40 fewer late arrivals for every thousand flights.
Key figures
On time
81.3%
Arrivals under 15 minutes late, of 348 completed flights
Avg delay
44 min
Across delayed arrivals only, not all flights
Cancelled
0.29%
National rate is 1.89%
1 hour+ late
4.3%
National rate is 8.3%
These figures cover 349 flights between September 2025 and August 2026. The median arrival is 5 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 634 flies
DL 634 flies DTW to LAX without a single fixed slot. Its most common scheduled departure was 12:30, used on 98 of 349 flights, with 12:16 (35 flights) next.
- Departs 12:3098 flights28.1%
- Departs 12:1635 flights10.0%
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 12:30 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.3%, and DL 634 runs 3 points better at 81.3%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
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Against the route
DL 634 next to DTW to LAX
Every carrier on DTW to LAX combined arrived on time 75.8% of the time across 2,361 flights, so DL 634 is 6 points ahead of it. Delta flew 1,954 flights on the same city pair under all its flight numbers, including this one, and those ran 75.8% on time. Across its whole network Delta Air Lines managed 81.1%, close to this flight's figure.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 634thin sample | 349 | 81.3% | 44 min | 0.29% | B+ |
| All Delta Air Lines on DTW–LAX | 1,954 | 75.8% | 58 min | 0.92% | B+ |
| All carriers on DTW–LAX | 2,361 | 75.8% | 59 min | 1.06% | B |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 634 quarter by quarter
Quarter by quarter DL 634 held fairly steady: 80.0% in Jul–Sep 2025, 83.8% in Oct–Dec 2025, 83.5% in Jan–Mar 2026, 76.9% in Apr–Jun 2026 and 82.3% in Jul–Sep 2026. A spread of 7 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Jul–Sep 202530 flights80.0%
- Oct–Dec 202580 flights83.8%
- Jan–Mar 202686 flights83.5%
- Apr–Jun 202691 flights76.9%
- Jul–Sep 202662 flights82.3%
Scale runs 70% to 90%.
By weekday, DL 634 did best on Wednesday at 90.0% on time and worst on Sunday at 63.3%. Each day rests on about 50 flights, so a gap of 27 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 634 runs when it is late
Most of the lateness is short. 33 of the 65 late arrivals were under half an hour behind, and 15 reached an hour or more.
- 15+ min early85 flights24.4%
- Within 15 min198 flights56.9%
- 15–29 min late33 flights9.5%
- 30–59 min late17 flights4.9%
- 1–2 hours late13 flights3.7%
- 2+ hours late2 flights0.6%
Scale runs 0% to 100%.
Share of 348 completed flights by arrival against schedule.
A late pushback is often recovered here: of 63 departures that left 15 minutes late or more, 23 still arrived on time. In the other direction, 25 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 LAX.
The worst days
Worst days for DL 634
The latest arrival of the period was on 31 January 2026, 5 hours 1 minute behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on four of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 31 January 2026 | 5 hours 1 minute | Carrier |
| 27 August 2026 | 2 hours 17 minutes | Carrier |
| 22 March 2026 | 1 hour 44 minutes | Late-arriving aircraft |
| 23 June 2026 | 1 hour 33 minutes | Carrier |
| 7 March 2026 | 1 hour 28 minutes | Carrier |
Delay causes
Why DL 634 runs late
Carrier accounts for 45% of the 2,845 delay minutes carriers reported here, and the remaining four split what is left.
- 45%Carrier
- 27%Late-arriving aircraft
- 23%National Airspace System
- 5%Extreme weather
The largest share of delay minutes, 45%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,284 of the 2,845 delay minutes reported here. The split is drawn from 2,845 delay minutes reported on DL 634.
Cancellations are rare at 0.29%, 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 4.3% 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 1,979 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 three other city pairs in the data, including ONT to SLC (11), SLC to ONT (11) and RSW to LGA (4), but none flew often enough under DL 634 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to DTW to LAX only.
One caution: this is a thin sample. 349 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 DL 634
For a booking, read DL 634 as 81.3% on time with 0.29% cancelled over 349 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- DTW to LAX, every carrier and departure
- LAX to DTW, the return direction
- Delta Air Lines 883 on the same route76.5%
- Delta Air Lines 694 on the same route64.2%
- Delta Air Lines 852 on the same route79.4%
- Detroit Metropolitan Wayne County (DTW) 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
- Worst months to fly in the US, ranked by the data
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.