Flight number record
DL 437
Delta Air Lines · Los Angeles to Boston
- Route
- LAX → BOS
- Departs
- 13:00
- Flights
- 342
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 437, check with Delta Air Lines.
DL 437 draws a C. About one flight in three arrives at least 15 minutes late, and the typical late arrival is close to two hours behind schedule. Build slack into anything you connect to. That rests on 342 flights, with a median arrival 1 minute early.
The national on-time rate over the same period is 77.3%, so DL 437 runs 10 points behind the country as a whole. Across a thousand flights that is about 98 extra late arrivals.
Key figures
On time
67.5%
Arrivals under 15 minutes late, of 335 completed flights
Avg delay
102 min
Across delayed arrivals only, not all flights
Cancelled
1.75%
National rate is 1.89%
1 hour+ late
15.5%
National rate is 8.3%
These figures cover 342 flights between September 2025 and August 2026. Beyond the headline rate, 15.5% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When DL 437 flies
DL 437 flies LAX to BOS without a single fixed slot. Its most common scheduled departure was 13:00, used on 95 of 342 flights, with 10:45 (76 flights) and 15:20 (38 flights) next.
- Departs 13:0095 flights27.8%
- Departs 10:4576 flights22.2%
- Departs 15:2038 flights11.1%
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 13:00 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.3%, and DL 437 runs 11 points worse at 67.5%. 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 437 next to LAX to BOS
Every carrier on LAX to BOS combined arrived on time 76.2% of the time across 4,797 flights, so DL 437 is 9 points behind it. Delta flew 1,240 flights on the same city pair under all its flight numbers, including this one, and those ran 75.9% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight trails by 14 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 437thin sample | 342 | 67.5% | 102 min | 1.75% | C |
| All Delta Air Lines on LAX–BOS | 1,240 | 75.9% | 89 min | 2.18% | B |
| All carriers on LAX–BOS | 4,797 | 76.2% | 80 min | 1.81% | B |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 437 quarter by quarter
DL 437 did not run the same all year. Its best quarter was Apr–Jun 2026 at 73.9% on time and its weakest Jul–Sep 2026 at 55.9%, a swing of 18 points on roughly 68 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 flights70.0%
- Oct–Dec 202573 flights63.4%
- Jan–Mar 202689 flights71.3%
- Apr–Jun 202688 flights73.9%
- Jul–Sep 202662 flights55.9%
Scale runs 45% to 80%.
By weekday, DL 437 did best on Tuesday at 77.1% on time and worst on Monday at 61.2%. Each day rests on about 49 flights, so a gap of 16 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 437 runs when it is late
The 109 late arrivals split 33 under half an hour, 24 between 30 and 60 minutes, and 52 an hour or more.
- 15+ min early63 flights18.8%
- Within 15 min163 flights48.7%
- 15–29 min late33 flights9.9%
- 30–59 min late24 flights7.2%
- 1–2 hours late26 flights7.8%
- 2+ hours late26 flights7.8%
Scale runs 0% to 100%.
Share of 335 completed flights by arrival against schedule.
19 of 104 late departures made up the time and arrived on time, 18% of them. In the other direction, 24 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 BOS.
The worst days
Worst days for DL 437
The latest arrival of the period was on 23 February 2026, 17 hours 53 minutes behind schedule; most of its delay minutes were filed as extreme weather. On three of the five worst days the largest share was filed as carrier-caused (crew, maintenance, fuelling, baggage).
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 23 February 2026 | 17 hours 53 minutes | Extreme weather |
| 17 October 2025 | 14 hours 9 minutes | Extreme weather |
| 13 July 2026 | 12 hours 6 minutes | Carrier |
| 21 November 2025 | 6 hours 2 minutes | Carrier |
| 9 March 2026 | 5 hours 8 minutes | Carrier |
Delay causes
Why DL 437 runs late
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 11,000 reported delay minutes.
- 34%Carrier
- 28%Late-arriving aircraft
- 19%National Airspace System
- 17%Extreme weather
- 1%Security
Extreme weather accounts for 17% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the quarterly figures above are the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.9 times the usual weather exposure. The split is drawn from 11,072 delay minutes reported on DL 437.
Cancellations sit at 1.75% against a national 1.89%, which is ordinary. Diversions add another 0.29%.
Connections and routes
What a delay on this flight costs
15.5% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
At 2,611 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 342 flights under DL 437 in the data flew LAX to BOS. 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. 342 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 437
For a booking, DL 437 is a flight to put a long connection behind. 15.5% of its completed flights arrived an hour or more late, which a short layover will not absorb. If the onward flight is on a separate ticket, the risk sits with you.
Related
Where to go next
- LAX to BOS, every carrier and departure
- BOS to LAX, the return direction
- Delta Air Lines 639 on the same route81.6%
- United Airlines 1783 on the same route82.0%
- American Airlines 12 on the same route78.8%
- American Airlines 2453 on the same route78.3%
- United Airlines 2210 on the same route90.7%
- JetBlue Airways 988 on the same route78.4%
- Los Angeles International (LAX) delay statistics
- Boston Logan International (BOS) 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
- How often a connection fails at the major US hubs
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.