Flight number record
F9 4345
Frontier Airlines · Denver to Los Angeles
- Route
- DEN → LAX
- Departs
- 22:39
- Flights
- 306
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s F9 4345, check with Frontier Airlines.
F9 4345 sits in the middle of the pack with a C+. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.3%. The late ones land about an hour behind schedule. That rests on 306 flights, with a median arrival 9 minutes early.
Key figures
On time
74.9%
Arrivals under 15 minutes late, of 303 completed flights
Avg delay
61 min
Across delayed arrivals only, not all flights
Cancelled
0.98%
National rate is 1.89%
1 hour+ late
7.9%
National rate is 8.3%
These figures cover 306 flights between September 2025 and August 2026. The median arrival is 9 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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Schedule
When F9 4345 flies
F9 4345 flies DEN to LAX without a single fixed slot. Its most common scheduled departure was 22:39, used on 110 of 306 flights, with 22:55 (75 flights) and 22:29 (54 flights) next.
- Departs 22:39110 flights35.9%
- Departs 22:5575 flights24.5%
- Departs 22:2954 flights17.6%
Scale runs 0% to 100%.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 22:39 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.1%, and F9 4345 runs 5 points better at 74.9%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
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Against the route
F9 4345 next to DEN to LAX
Every carrier on DEN to LAX combined arrived on time 78.7% of the time across 7,708 flights, so F9 4345 is 4 points behind it. Frontier flew 797 flights on the same city pair under all its flight numbers, including this one, and those ran 83.4% on time. Across its whole network Frontier Airlines managed 72.7%, which this flight beats by 2 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| F9 4345thin sample | 306 | 74.9% | 61 min | 0.98% | C+ |
| All Frontier Airlines on DEN–LAX | 797 | 83.4% | 68 min | 0.75% | B+ |
| All carriers on DEN–LAX | 7,708 | 78.7% | 63 min | 0.53% | B+ |
| Frontier Airlines, whole network | 213,022 | 72.7% | 84 min | 2.05% | C |
Across the year
F9 4345 quarter by quarter
Quarter by quarter F9 4345 held fairly steady: 77.5% in Oct–Dec 2025, 75.4% in Jan–Mar 2026, 75.3% in Apr–Jun 2026 and 71.2% in Jul–Sep 2026. A spread of 6 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Jul–Sep 202526 flights—
- Oct–Dec 202580 flights77.5%
- Jan–Mar 202665 flights75.4%
- Apr–Jun 202674 flights75.3%
- Jul–Sep 202661 flights71.2%
Scale runs 65% to 85%. Rows with fewer than 30 flights show a dash.
By weekday, F9 4345 did best on Tuesday at 85.3% on time and worst on Friday at 66.0%. Each day rests on about 44 flights, so a gap of 19 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late F9 4345 runs when it is late
F9 4345 often beats the schedule: 122 of 303 completed flights, 40%, arrived 15 minutes or more early. The 76 late arrivals split 22 under half an hour, 30 between 30 and 60 minutes, and 24 an hour or more.
- 15+ min early122 flights40.3%
- Within 15 min105 flights34.7%
- 15–29 min late22 flights7.3%
- 30–59 min late30 flights9.9%
- 1–2 hours late18 flights5.9%
- 2+ hours late6 flights2.0%
Scale runs 0% to 100%.
Share of 303 completed flights by arrival against schedule.
29 of 100 late departures made up the time and arrived on time, 29% of them. Only 5 left on time and still arrived late.
The worst days
Worst days for F9 4345
The latest arrival of the period was on 21 June 2026, 7 hours 13 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 21 June 2026 | 7 hours 13 minutes | Carrier |
| 22 December 2025 | 4 hours 40 minutes | Carrier |
| 28 December 2025 | 3 hours 6 minutes | Late-arriving aircraft |
| 19 February 2026 | 2 hours 36 minutes | Carrier |
| 6 March 2026 | 2 hours 16 minutes | Late-arriving aircraft |
Delay causes
Why F9 4345 runs late
Carrier accounts for 51% of the 4,650 delay minutes carriers reported here, and the remaining four split what is left.
- 51%Carrier
- 40%Late-arriving aircraft
- 6%National Airspace System
- 2%Extreme weather
40% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 4,650 reported delay minutes here, that single category outweighs weather by 18 to one. The split is drawn from 4,650 delay minutes reported on F9 4345.
Cancellations sit at 0.98% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
7.9% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, 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.
Every one of the 306 flights under F9 4345 in the data flew DEN to LAX. The number was not reused on any other city pair, which makes this a clean record of one route.
One caution: this is a thin sample. 306 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 F9 4345
For a booking, read F9 4345 as 74.9% on time with 0.98% cancelled over 306 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- DEN to LAX, every carrier and departure
- LAX to DEN, the return direction
- United Airlines 1638 on the same route91.8%
- United Airlines 1013 on the same route83.8%
- United Airlines 405 on the same route91.2%
- United Airlines 2240 on the same route75.3%
- United Airlines 531 on the same route76.3%
- United Airlines 1195 on the same route82.5%
- Denver International (DEN) delay statistics
- Los Angeles International (LAX) delay statistics
- Frontier Airlines on-time record
- Every Frontier Airlines flight number with a record
- The most and least reliable flight numbers in the US
- Why the first flight of the morning is statistically safest
A flight number here means Frontier Airlines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.
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.