Carrier route record

F9LAX→DEN

Frontier Airlines · Los Angeles to Denver

Flights: 762
Period: July 2025 to June 2026
Share of route: 10%
Carriers: 5

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Frontier Airlines.

Frontier on LAX to DEN lands a B+, 4 points better than the national rate of 77.6%. About one flight in six arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That is a workable record, not a spotless one. That rests on 762 flights. The strongest carrier on the route with a full sample, United Airlines, flew 3,067 at 87.1% on time.

United Airlines is the most reliable of the four carriers covered here at 87.1% on time across 3,067 flights.

On time

81.9%

Arrivals under 15 minutes late, of 756 completed flights

Avg delay

90 min

Across delayed arrivals only, not all flights

Cancelled

0.79%

National rate is 1.81%

Whole route

81.7%

Every carrier on LAX to DEN, 7,721 flights

These figures cover 762 flights between July 2025 and June 2026. The median arrival is 11 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.

Carrier by carrier

Frontier against every carrier on LAX to DEN

Frontier flew 762 of the 7,721 flights on LAX to DEN, about 10% of it. Its 81.9% on time is about level with the route as a whole at 81.7%. Ranked by on-time rate it is number two of five carriers on the route, where the range runs from United at 87.1% to Southwest at 74.1%.

The choice of carrier is not cosmetic here. United Airlines arrives on time 87.1% of the time; Southwest Airlines manages 74.1%. Sample sizes sit next to every figure, because a two-point gap across 1,917 flights means less than a ten-point one.

On-time performance by carrier on LAX to DEN
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	3,067	87.1%	68 min	0.10%	A+
Frontier Airlines (this page)	762	81.9%	90 min	0.79%	B+
SkyWest Airlines	1,231	81.2%	61 min	0.81%	B+
Delta Air Lines	744	79.7%	85 min	1.48%	B
Southwest Airlines	1,917	74.1%	52 min	0.47%	C+

The spread between United and Southwest is 13 points, wide enough that it should decide the booking. On a hundred trips that is 13 more arrivals inside the on-time window.

Flight by flight

Frontier flight numbers on LAX to DEN

F9 315606:1588.1% · 361 flights

Departure window

When Frontier runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 15 points, against 13 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am357 flights87.9%
8am–11am36 flights86.1%
11am–2pm65 flights84.6%
2pm–5pm175 flights73.8%
5pm–8pm—
8pm–5am129 flights73.2%

Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 87.9% of the time, against 73.2% for the overnight window. That is 15 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 357 flights scheduled in it.

Across the year

Frontier on LAX to DEN through the year

Darker means more delays. Figures are on-time percentages.January best, September worst

Delays peak in September, when the on-time rate falls to 65.7%. January is the strongest month at 88.7%. Moving a flexible trip across that boundary buys 23 points. June was the busiest month here, with 83 flights.

Across the week, Sunday is the strongest day at 85.5% on time and Saturday the weakest at 77.6%. 8 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Frontier runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 56% of the 12,000 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.

Late-arriving aircraft
56%
Carrier
27%
National Airspace System
17%
Extreme weather
0%

56% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 12,000 reported delay minutes here, that single category outweighs weather by 56 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 12,342 reported delay minutes.

The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 87.9% on time here.

Cancellations are rare at 0.79%, below the national 1.81% 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 costs

7.7% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last an hour and a half, which a normal layover absorbs.

The 862 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The return leg runs 81.1% on time across 762 flights, within about 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. 762 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 Frontier on LAX to DEN

Put together: treat all of this as provisional. 762 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 81.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 756 completed flights over 12 months sit behind that.

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.

Key figures