Carrier route record

DLSLC→IDA

Delta Air Lines · Salt Lake City to Idaho Falls

Flights: 317
Period: September 2025 to August 2026
Share of route: 27%
Carriers: 2

Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Delta Air Lines.

Delta on SLC to IDA 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 about an hour on average. That rests on 317 flights, with a median arrival 8 minutes early.

Set against the rest of the country, Delta's SLC to IDA record is 4 points better than the US average of 77.3%. That gap is worth roughly 41 fewer late arrivals for every thousand flights.

On time

81.4%

Arrivals under 15 minutes late, of 312 completed flights

Avg delay

64 min

Across delayed arrivals only, not all flights

Cancelled

1.26%

National rate is 1.89%

Whole route

89.6%

Every carrier on SLC to IDA, 1,195 flights

These figures cover 317 flights between September 2025 and August 2026. The median arrival is 8 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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Carrier by carrier

Delta against every carrier on SLC to IDA

Delta flew 317 of the 1,195 flights on SLC to IDA, about 27% of it. Its 81.4% on time is 8 points worse than the route as a whole, which runs 89.6%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from SkyWest at 92.5% to Delta at 81.4%.

Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.

On-time performance by carrier on SLC to IDA
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlines	878	92.5%	70 min	0.11%	A+
Delta Air Lines (this page)thin sample	317	81.4%	64 min	1.26%	B

Flight by flight

Delta flight numbers on SLC to IDA

DL 260821:3081.4% · 317 flights

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Departure window

When Delta runs best on this route

Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 317 flights.

The overnight block holds up unusually well at 81.4% on time across 316 flights. Red-eyes fly into empty airspace and empty gates, and they are the first rotation of the aircraft's day rather than the last. The 8pm–5am window is the busiest, with 316 flights scheduled in it.

Across the year

Delta on SLC to IDA through the year

Jul–Sep 202530 flights76.7%
Oct–Dec 202580 flights71.8%
Jan–Mar 202665 flights82.5%
Apr–Jun 202680 flights91.2%
Jul–Sep 202662 flights82.0%

Scale runs 65% to 95%.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 81.4% on time across 317 flights.

Delta on SLC to IDA did not run the same all year. Its best quarter was Apr–Jun 2026 at 91.2% on time and its weakest Oct–Dec 2025 at 71.8%, a swing of 19 points on roughly 63 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.

Across the week, Wednesday is the strongest day at 88.4% on time and Friday the weakest at 71.1%, a spread of 17 points.

Arrival by arrival

How late Delta on SLC to IDA runs when it is late

Delta on SLC to IDA often beats the schedule: 78 of 312 completed flights, 25%, arrived 15 minutes or more early. The 58 late arrivals split 14 under half an hour, 22 between 30 and 60 minutes, and 22 an hour or more.

15+ min early78 flights25.0%
Within 15 min176 flights56.4%
15–29 min late14 flights4.5%
30–59 min late22 flights7.1%
1–2 hours late18 flights5.8%
2+ hours late4 flights1.3%

Scale runs 0% to 100%.

Share of 312 completed flights by arrival against schedule.

8 of 59 late departures made up the time and arrived on time, 14% of them. 7 flights left on time and still arrived late.

The worst days

Worst days for Delta on SLC to IDA

The latest arrival of the period was on 29 July 2026, 10 hours 30 minutes behind schedule; most of its delay minutes were filed as extreme weather. The five worst days are spread across July, December, January and October, with no single month standing out.

The latest arrivals of Delta on SLC to IDA in the period
Date	Arrived late by	Largest filed cause
29 July 2026	10 hours 30 minutes	Extreme weather
14 December 2025	3 hours 1 minute	Late-arriving aircraft
2 January 2026	2 hours 49 minutes	Carrier
24 October 2025	2 hours 17 minutes	Late-arriving aircraft
19 July 2026	1 hour 34 minutes	Carrier

Delay causes

Why Delta runs late on this route

Carrier accounts for 50% of the 3,699 delay minutes carriers reported here, and the remaining four split what is left.

Carrier
50%
Late-arriving aircraft
22%
Extreme weather
19%
National Airspace System
10%

Extreme weather accounts for 19% 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 monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 3.1 times the usual weather exposure. The split is drawn from 3,699 reported delay minutes.

The largest share of delay minutes, 50%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,833 of the 3,699 delay minutes reported here.

Cancellations sit at 1.26% against a national 1.89%, which is ordinary. Diversions add another 0.32%.

Connections and stage length

What a delay here costs

7.1% of arrivals land an hour or more late, close to the national 8.3%, so 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 189 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 8pm–5am window matters as much as it does.

The return leg is a different operation and performs like one: it runs 89.8% on time across 317 flights, 8 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 8 points of difference.

One caution: this is a thin sample. 317 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 Delta on SLC to IDA

Put together: treat all of this as provisional. 317 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 81.4% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 312 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures