Flight number record

DL 506

Delta Air Lines · Seattle to Miami

Route: SEA → MIA
Departs: 08:00
Flights: 365
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 506, check with Delta Air Lines.

DL 506 lands a B, level with the national rate of 77.6%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 365 flights, with a median arrival 6 minutes early.

On time

78.2%

Arrivals under 15 minutes late, of 358 completed flights

Avg delay

60 min

Across delayed arrivals only, not all flights

Cancelled

1.37%

National rate is 1.81%

1 hour+ late

5.6%

National rate is 8.1%

These figures cover 365 flights between July 2025 and June 2026. The median arrival is 6 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.

Schedule

When DL 506 flies

DL 506 flies SEA to MIA without a single fixed slot. Its most common scheduled departure was 08:00, used on 111 of 365 flights, with 07:55 (41 flights) and 07:35 (37 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 08:00111 flights30.4%
Departs 07:5541 flights11.2%
Departs 07:3537 flights10.1%

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 08:00 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 84.1%, and DL 506 runs 6 points worse at 78.2%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

Against the route

DL 506 next to SEA to MIA

Every carrier on SEA to MIA combined arrived on time 77.3% of the time across 1,179 flights, so DL 506 is about level with it. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 3 points.

DL 506 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 506	365	78.2%	60 min	1.37%	B
All Delta Air Lines on SEA–MIA	365	78.2%	60 min	1.37%	B
All carriers on SEA–MIA	1,179	77.3%	52 min	0.93%	B+
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 506 quarter by quarter

DL 506 did not run the same all year. Its best quarter was Oct–Dec 2025 at 85.4% on time and its weakest Jul–Sep 2025 at 68.9%, a swing of 17 points on roughly 91 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 202592 flights68.9%
Oct–Dec 202592 flights85.4%
Jan–Mar 202690 flights73.9%
Apr–Jun 202691 flights84.6%

Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.

By weekday, DL 506 did best on Tuesday at 84.9% on time and worst on Friday at 70.6%. Each day rests on about 52 flights, so a gap of 14 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 506 runs late

One category carries most of the weight here. Carrier accounts for 56% of the 4,695 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.

Carrier
56%
National Airspace System
40%
Extreme weather
3%
Late-arriving aircraft
0%

The largest share of delay minutes, 56%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 2,652 of the 4,695 delay minutes reported here. The split is drawn from 4,695 delay minutes reported on DL 506.

Cancellations sit at 1.37% against a national 1.81%, which is ordinary. Diversions add another 0.55%.

Connections and routes

What a delay on this flight costs

5.6% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.

At 2,724 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.

DL 506 is not only a SEA to MIA flight. It also flew MIA to SEA (263 flights, 59.4% 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. 365 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.

Other routes flown as DL 506
Also flown as	Flights	On time	Avg delay	Cancelled	Grade
MIA to SEAthin sample	263	59.4%	98 min	2.28%	D

What to do with this

Booking DL 506

For a booking, read DL 506 as 78.2% on time with 1.37% cancelled over 365 flights. Those are rates from the past twelve months, not a forecast for any particular day.

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