Route profile
SLC→STL
Flight reliability, delays and best times to fly from Salt Lake City to St. Louis, 1,156 miles.
Right now
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Route reliability
July 2023 – July 2026
Better than 88% of comparable major US routes (4,598 compared)
Calculated from 3,016 flights. How this is calculated
SLC → STL arrives on time 84.3% of the time; the return trip, STL → SLC, arrives on time 88.9% of the time, a 4.6-point gap between the two directions of the same city pair.
SLC → STL spends 23.9 minutes on the ground on a 1,156-mile trip: 17.2 minutes from pushback to wheels-up at SLC and 6.7 minutes from touchdown to gate at STL.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What stands out
This route has stayed remarkably steady year over year, a smaller swing than 100% of 5,368 comparable routes.
84.5% on time over the most recent 12 months (2025-08 to 2026-07), against 84.5% in the 12 months before (2024-08 to 2025-07), virtually unchanged.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Ranked against every other route with the same kind of figure and at least 5,368 in the comparison.
What sets this route apart
Where SLC to STL differs most from similar routes by hour, weekday, month and airline, July 2023 – July 2026.
SLC to STL is at its best against routes of similar length for flights scheduled at 5 PM: 83.9% arrive on time, 16.7 points ahead of the 67.2% those routes manage at that hour. Against all other routes the gap is 14.1 points.
SLC to STL holds up on Mondays better than routes of similar length do: 85.9% on time to their 75.9%, a 10 points lead. Against all other routes the gap is 8.7 points.
June is kinder to SLC to STL than to routes of similar length: 84.8% on time against 71.5%, 13.3 points better. Against all other routes the gap is 12.1 points.
Delta Air Lines does better on SLC to STL than on its routes of similar length: 84.1% on time here, 80.6% there, 3.5 points apart. Against all other routes the gap is 2.6 points.
SLC to STL against comparable routes
July 2023 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Hour: 5 PM departures | 83.9% | routes of similar length | 67.2% | +16.7 pts | 353 here, 139,707 there |
| Weekday: Monday | 85.9% | routes of similar length | 75.9% | +10.0 pts | 453 here, 346,526 there |
| Month: June | 84.8% | routes of similar length | 71.5% | +13.3 pts | 264 here, 187,001 there |
| Airline: Delta Air Lines | 84.1% | routes of similar length | 80.6% | +3.5 pts | 2,952 here, 409,518 there |
Each comparison pools the flights of other routes, with this route’s own left out. Similar length means within 15% of this route’s 1,156 miles, with at least 5 such routes. A bucket is set against the most comparable group that has enough flights: similar length, then the same origin (at least 3 routes), then all other routes. Hours, weekdays and months appear only where both sides have 120 completed flights, and airlines where both have 600. The gap must be at least 2 points and 2 standard errors, and only the largest gap each way is kept per measure. These are differences in the flights counted, not causes.
When it goes wrong
July 2023 – July 2026
29 min late
against a median of 9 min early
Percentiles over 3,016 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at STL after arriving from SLC.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 29% | High risk |
| 45 min | 15% | High risk |
| 60 min | 9.5% | Some risk |
| 90 min | 5.2% | Some risk |
| 120 min | 3.2% | Low risk |
This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 0.43% of the time and diverts 0.17% of the time, which a late arrival never shows up in.
Chance of missing is the share of 2,998 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.
The worst tenth of arrivals on this route land at least 29 minutes late (90th-percentile gate arrival delay), over 3,016 operations.
Any other layover length: connection checker.
Best time to fly
SLC → STL flights departing 9 AM–12 PM arrived on time 87.5% of the time, against 79.1% for 6–9 PM departures, a gap of 8.4 percentage points.
By departure window
By departure hour
- 12 AM to 8 AM: too few flights to score
- 9 AM: 87.6% on time from 1,090 flights
- 10 AM to 12 PM: too few flights to score
- 1 PM: 84.3% on time from 403 flights
- 2 PM: 85.2% on time from 213 flights
- 3 PM to 4 PM: too few flights to score
- 5 PM: 83.9% on time from 355 flights
- 6 PM to 7 PM: too few flights to score
- 8 PM: 79.2% on time from 469 flights
- 9 PM: 81.4% on time from 283 flights
- 10 PM to 11 PM: too few flights to score
Departure windows with fewer than 120 flights are not scored.
Why SLC → STL runs late
July 2023 – July 2026
crew, maintenance, boarding and fueling, all within the carrier’s control
the inbound aircraft was late, so this flight started late
airspace and airport capacity, including weather-driven flow control
weather severe enough to stop this flight specifically
screening or terminal security incidents
Share of the delay minutes US DOT attributed to each cause for SLC → STL. Only delays of 15 minutes or more are attributed.
Airlines on this route
Carriers with at least 200 flights, by the airline that operated each one.
| Carrier | Flights | On time | Cancelled | Median delay | Severe |
|---|---|---|---|---|---|
| Delta Air Lines | 2,970 | 84.1% | 0.44% | -9 min | 5.4% |
Flights on this route
Flight numbers with at least 600 operations here and still on the schedule.
Weekly and seasonal patterns
By day of week
Tuesday is historically the most reliable day and Sunday the least, a gap of 8.4 percentage points.
By month
- Jan: 80.4%
- Feb: 84.7%
- Mar: 86.1%
- Apr: 81.1%
- May: 86.5%
- Jun: 84.8%
- Jul: 81.6%
- Aug: 82.8%
- Sep: 82.6%
- Oct: 90.3%
- Nov: 88.4%
- Dec: 81.9%
January is historically the weakest month and October the strongest, a spread of 9.9 percentage points.
Reliability over time
July 2023 – July 2026
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 84.5% against 84.5% in the 12 months before — broadly unchanged.
Data and methodology
Calculated by FlyerIntel from 3,016 SLC → STL flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.
Full methodology · Data sources · Report a problem
Related research: How Long a Layover Needs to Be · Two Airlines on One Route · Best Time of Day to Fly From Major US Airports
Analysis last recomputed