Carrier route record
DLSLC→IDA
Delta Air Lines · Salt Lake City to Idaho Falls
- Flights
- 317
- Period
- July 2025 to June 2026
- Share of route
- 27%
- Carriers
- 2
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on SLC to IDA 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 a little over an hour on average. That is a workable record, not a spotless one. That rests on 317 flights, with a median arrival 7 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate Delta on SLC to IDA from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
78.0%
Arrivals under 15 minutes late, of 313 completed flights
Avg delay
69 min
Across delayed arrivals only, not all flights
Cancelled
0.95%
National rate is 1.81%
Whole route
89.3%
Every carrier on SLC to IDA, 1,189 flights
These figures cover 317 flights between July 2025 and June 2026. Beyond the headline rate, 9.3% 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.
Carrier by carrier
Delta against every carrier on SLC to IDA
Delta flew 317 of the 1,189 flights on SLC to IDA, about 27% of it. Its 78.0% on time is 11 points worse than the route as a whole, which runs 89.3%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from SkyWest at 93.3% to Delta at 78.0%.
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.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 872 | 93.3% | 76 min | 0.11% | A+ |
| Delta Air Lines (this page)thin sample | 317 | 78.0% | 69 min | 0.95% | B+ |
Flight by flight
Delta flight numbers on SLC to IDA
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 77.9% 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 202592 flights68.5%
- Oct–Dec 202580 flights71.8%
- Jan–Mar 202665 flights82.5%
- Apr–Jun 202680 flights91.2%
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 78.0% 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 Jul–Sep 2025 at 68.5%, a swing of 23 points on roughly 79 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, Saturday is the strongest day at 86.4% on time and Friday the weakest at 66.7%. 20 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Delta runs late on this route
One category carries most of the weight here. Carrier accounts for 63% of the 4,758 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.
- 63%Carrier
- 21%Late-arriving aircraft
- 11%Extreme weather
- 5%National Airspace System
Extreme weather accounts for 11% 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 1.8 times the usual weather exposure. The split is drawn from 4,758 reported delay minutes.
The largest share of delay minutes, 63%, 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 3,010 of the 4,758 delay minutes reported here.
Cancellations sit at 0.95% against a national 1.81%, which is ordinary. Diversions add another 0.32%.
Connections and stage length
What a delay here costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.3% 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 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 88.2% on time across 317 flights, 10 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 10 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 78.0% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 313 completed flights over 12 months sit behind that.
Related
Where to go next
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.