Itineraries flown on 20+ days in the Jun 6 – Jul 31, 2026 schedule · each leg’s record Aug 2025 – Jul 2026

No clear winner: airlines and hours on this route all land within a few points of 4 in 5 on time.

Nonstops


United	COS	DEN	1h 06m	82%	1.4%	3,879	Flying now
Southwest	COS	DEN	55m	78%	0.3%	1,129	Flying now

Best connections, one ticket

Most reliable Quickest (80%+ on time)

Ranked by chance you reach Denver on time. Total trip = scheduled departure to arrival, layover included. Layovers up to 4 hours. Pick a connection for the details.


Delta Details →	COS 06:00 → ATL 10:54DL 1074	1h 56m Atlanta	ATL 12:50 → DEN 14:04DL 957	8h 04m	97%	85%
Southwest Details →	COS 06:10 → LAS 07:05WN 3313	1h 50m Las Vegas	LAS 08:55 → DEN 11:50WN 247	5h 40m	96%	85%
Delta Details →	COS 08:14 → SLC 10:15DL 3940 · flown by SkyWest	3h 05m Salt Lake City	SLC 13:20 → DEN 14:56DL 1623	6h 42m	100%	85%
United Details →	COS 05:44 → ORD 09:45UA 5790 · flown by SkyWest	1h 09m Chicago	ORD 10:54 → DEN 12:45UA 581	7h 01m	91%	84%
United Details →	COS 07:30 → IAH 11:03UA 4029 · flown by Mesa	1h 30m Houston	IAH 12:33 → DEN 14:17UA 2168	6h 47m	94%	82%
Southwest Details →	COS 06:45 → PHX 07:35WN 4256	3h 25m Phoenix	PHX 11:00 → DEN 13:45WN 3262	7h 00m	100%	81%
Southwest Details →	COS 05:10 → DAL 08:00WN 1218	3h 35m Dallas	DAL 11:35 → DEN 12:35WN 3563	7h 25m	100%	74%
Delta Details →	COS 13:40 → ATL 18:45DL 2427	2h 09m Atlanta	ATL 20:54 → DEN 22:12DL 493	8h 32m	94%	73%
Tight connection: often missed
American Details →	COS 10:44 → DFW 13:36AA 1697	50m Dallas-Fort Worth	DFW 14:26 → DEN 15:30AA 1832	4h 46m	74%	44%
Southwest Details →	COS 19:55 → LAS 20:55WN 1227	55m Las Vegas	LAS 21:50 → DEN 00:40 +1WN 2230	4h 50m	55%	26%
Southwest Details →	COS 12:20 → SAN 13:35WN 1232	1h 20m San Diego	SAN 14:55 → DEN 18:20WN 3497	6h 00m	58%	18%

Same layover, different day-part

How often the first flight arrives too late to connect (45 min minimum), for one-ticket layovers of 45–80 minutes.

Morning

PHX · 1h 15m · leaves 06:45 4%

ATL · 51m · leaves 06:00 11%

Afternoon and evening

SLC · 49m · leaves 18:20 14%

IAH · 46m · leaves 12:06 25%

LAS · 55m · leaves 19:55 45%

Delays build through the day, so an afternoon first leg eats the layover. A short connection is fine early in the morning and a gamble later on.

Mixing airlines

One ticketMiss it and the airline rebooks you; bags go through. 45 min is enough.

Separate ticketsMiss it and you buy a new ticket. Re-check bags, clear security again: we require 90 min.


Delta DL 3940 COS 08:14 → SLC United UA 4720 SLC 13:05 → DEN Connection details →	2h 50m	6h 37m	99%	91%
Southwest WN 3313 COS 06:10 → LAS United UA 1315 LAS 09:37 → DEN Connection details →	2h 32m	6h 31m	96%	89%
Delta DL 4449 COS 18:20 → SLC Frontier F9 4252 SLC 22:50 → DEN Connection details →	2h 34m	6h 18m	98%	78%

Rank all connections, any airlines →

Regional partners count as the airline that sells them: SkyWest flying Delta Connection is one Delta ticket.

How these are worked out. Makes the connection: share of the last year’s flights where the first flight arrived with at least 45 minutes to spare (90 on separate tickets). Arrives on time: first flight not cancelled × connection made × second flight not cancelled and arriving within 15 minutes. Not yet counted: the second flight also leaving late (which helps), gate-to-gate distance at the hub, and rebooking after a missed connection.

About this data: US DOT on-time records, Aug 2025 – Jul 2026, all US airlines; regional flights count under the airline that sells them. Schedules (which flights and connections exist, and their times) are as of Jun 6 – Jul 31, 2026; seasonal flights outside that window aren’t ranked. Rebuilt monthly. JSON