Flight number record

DL 437

Delta Air Lines · Los Angeles to Boston

Route: LAX → BOS
Departs: 13:00
Flights: 341
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 437, check with Delta Air Lines.

DL 437 sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.6%. The late ones land an hour and a half behind schedule. That rests on 341 flights, with a median arrival 3 minutes early.

The national on-time rate over the same period is 77.6%, so DL 437 runs 4 points behind the country as a whole. Across a thousand flights that is about 43 extra late arrivals.

On time

73.3%

Arrivals under 15 minutes late, of 337 completed flights

Avg delay

99 min

Across delayed arrivals only, not all flights

Cancelled

1.17%

National rate is 1.81%

1 hour+ late

11.9%

National rate is 8.1%

These figures cover 341 flights between July 2025 and June 2026. Beyond the headline rate, 11.9% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

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 341 flights, with 15:25 (65 flights) and 15:20 (59 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 13:0095 flights27.9%
Departs 15:2565 flights19.1%
Departs 15:2059 flights17.3%

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 13:00 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.8%, and DL 437 runs 6 points worse at 73.3%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

DL 437 next to LAX to BOS

Every carrier on LAX to BOS combined arrived on time 78.4% of the time across 4,718 flights, so DL 437 is 5 points behind it. Delta flew 1,230 flights on the same city pair under all its flight numbers, including this one, and those ran 78.6% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 8 points.

DL 437 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 437thin sample	341	73.3%	99 min	1.17%	C
All Delta Air Lines on LAX–BOS	1,230	78.6%	86 min	1.71%	B
All carriers on LAX–BOS	4,718	78.4%	81 min	1.42%	B
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 437 quarter by quarter

DL 437 did not run the same all year. Its best quarter was Jul–Sep 2025 at 82.4% on time and its weakest Oct–Dec 2025 at 63.4%, a swing of 19 points on roughly 85 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 202591 flights82.4%
Oct–Dec 202573 flights63.4%
Jan–Mar 202689 flights71.3%
Apr–Jun 202688 flights73.9%

Scale runs 55% to 90%. Rows with fewer than 30 flights show a dash.

By weekday, DL 437 did best on Tuesday at 82.0% on time and worst on Thursday at 68.8%. Each day rests on about 49 flights, so a gap of 13 points is worth noticing but could still narrow in another year.

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 8,946 reported delay minutes.

Carrier
31%
Late-arriving aircraft
30%
Extreme weather
21%
National Airspace System
18%
Security
0%

Extreme weather accounts for 21% 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 3.4 times the usual weather exposure. The split is drawn from 8,946 delay minutes reported on DL 437.

Cancellations sit at 1.17% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

Connections and routes

What a delay on this flight costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 11.9% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum 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 341 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. 341 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 one of the weaker ways to fly LAX to BOS: 5 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 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures