Flight number record

DL 2021

Delta Air Lines · Miami to Salt Lake City

Route: MIA → SLC
Departs: 07:00
Flights: 364
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 2021, check with Delta Air Lines.

DL 2021 lands a B+, about a point worse than the national rate of 77.6%. About one flight in four 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 364 flights, with a median arrival 1 minute early.

On time

76.5%

Arrivals under 15 minutes late, of 362 completed flights

Avg delay

57 min

Across delayed arrivals only, not all flights

Cancelled

0.55%

National rate is 1.81%

1 hour+ late

5.5%

National rate is 8.1%

These figures cover 364 flights between July 2025 and June 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.

Schedule

When DL 2021 flies

DL 2021 flies MIA to SLC without a single fixed slot. Its most common scheduled departure was 07:00, used on 55 of 364 flights, with 06:43 (47 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 07:0055 flights15.1%
Departs 06:4347 flights12.9%

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 07:00 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and DL 2021 runs 13 points worse at 76.5%. 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 2021 next to MIA to SLC

Every carrier on MIA to SLC combined arrived on time 76.7% of the time across 776 flights, so DL 2021 is about level with it. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 5 points.

DL 2021 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 2021thin sample	364	76.5%	57 min	0.55%	B+
All Delta Air Lines on MIA–SLCthin sample	364	76.5%	57 min	0.55%	B+
All carriers on MIA–SLC	776	76.7%	62 min	0.90%	B+
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 2021 quarter by quarter

DL 2021 did not run the same all year. Its best quarter was Apr–Jun 2026 at 86.8% on time and its weakest Jul–Sep 2025 at 65.2%, a swing of 22 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 flights65.2%
Oct–Dec 202591 flights68.1%
Jan–Mar 202690 flights86.4%
Apr–Jun 202691 flights86.8%

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

By weekday, DL 2021 did best on Tuesday at 86.5% on time and worst on Sunday at 65.4%. Each day rests on about 52 flights, so a gap of 21 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 2021 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 4,871 reported delay minutes.

Late-arriving aircraft
41%
Carrier
31%
National Airspace System
24%
Extreme weather
4%

41% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 4,871 reported delay minutes here, that single category outweighs weather by 11 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 4,871 delay minutes reported on DL 2021.

Cancellations are rare at 0.55%, below the national 1.81% 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

5.5% 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 2,088 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 364 flights under DL 2021 in the data flew MIA to SLC. 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. 364 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 2021

For a booking, read DL 2021 as 76.5% on time with 0.55% cancelled over 364 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