Route reliability record
COS→SLC
Colorado Springs to Salt Lake City
- Flights
- 721
- Period
- September 2025 to August 2026
- Distance
- 411 mi
- Carriers
- 1
This route earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 15 points better than the national rate of 77.3%. When something does go wrong the average delay runs a little over an hour. That rests on 721 COS to SLC flights, with a median arrival 14 minutes early.
Best time to fly COS to SLC: a 8am–11am departure, ideally on a Monday. Flights in that window arrived on time 94.8% of the time and Monday flights 95.3%, against 91.9% for the route overall.
Set against the rest of the country, this route's record is 15 points better than the US average of 77.3%. That gap is worth roughly 146 fewer late arrivals for every thousand flights.
Key figures
On time
91.9%
Arrivals under 15 minutes late, of 719 completed flights
Avg delay
76 min
Across delayed arrivals only, not all flights
Cancelled
0.14%
National rate is 1.89%
Best carrier
SkyWest
91.9% on time across 721 flights
These figures cover 721 flights between September 2025 and August 2026. The median arrival is 14 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
Which airline is most reliable on COS to SLC
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 | 721 | 91.9% | 76 min | 0.14% | A+ |
Flight by flight
Flights on COS to SLC
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Departure window
The best time of day to leave
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 721 flights.
- 5am–8am—
- 8am–11am365 flights94.8%
- 11am–2pm153 flights94.1%
- 2pm–5pm—
- 5pm–8pm203 flights85.1%
- 8pm–5am—
Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 94.8% of the time, against 85.1% for the evening window. That is 10 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 365 flights scheduled in it.
Explore
Filter COS to SLC by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On COS to SLC, the best departure window is 8am–11am at 94.8% on time and the worst is 5pm–8pm at 85.1%, a real gap of 9.7 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am—
- 8–11am94.8%
- 11am–2pm94.1%
- 2–5pm—
- 5–8pm85.1%
- 8pm–5am—
best all US flightsScale 60% to 100%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 27 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
August is the worst month at 72.6% on time, 27 points below October, the best at 100.0%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. March was the busiest month here, with 62 flights.
Across the week, Monday is the strongest day at 95.3% on time and Sunday the weakest at 84.6%, a spread of 11 points.
Delay causes
Why this route gets delayed
Carrier accounts for 54% of the 4,398 delay minutes carriers reported here, and the remaining four split what is left.
- 54%Carrier
- 44%Extreme weather
- 2%National Airspace System
Extreme weather accounts for 44% 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 7.3 times the usual weather exposure. The split is drawn from 4,398 reported delay minutes.
The largest share of delay minutes, 54%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,356 of the 4,398 delay minutes reported here.
Cancellations are rare at 0.14%, below the national 1.89% 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 stage length
What a delay here actually costs
Badly late arrivals are rare here: only 2.8% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
At 411 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 8am–11am window matters as much as it does.
The return leg runs 91.9% on time across 721 flights, within half a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
One caution: this is a thin sample. 721 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.
Work out the risk of missing a connection in SLC after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 721 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 91.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 719 completed flights over 12 months sit behind that.
Common questions
COS to SLC questions
How often is COS to SLC delayed?
About one flight in twelve arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 8.1% of the 721 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
How reliable is COS to SLC compared with the rest of the country?
91.9% of flights arrive on time here against a national 77.3%, a difference of 15 points in its favour. That is worth a A+ on this site's grading scale.
What time of day has the fewest delays on COS to SLC?
The 8am–11am departure window is the strongest at 94.8% on time. The 5pm–8pm window is the weakest at 85.1%, 10 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are August delays on COS to SLC?
August is the weakest month at 72.6% on time, compared with 100.0% in October. Across the year that is 27 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- SLC to COS — the return legseparate record
- Salt Lake City International (SLC) delay statistics
- COS to DEN, a related route81.4%
- DEN to SLC, a related route78.2%
- COS to DFW, a related route77.9%
- SkyWest Airlines on-time record91.9%
- The most punctual routes in the US, and the least
- The best time of day to fly, according to 7.05 million flight records
Direction matters. COS to SLC and SLC to COS are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.