Flight number record

F9 3439

Frontier Airlines · Denver to San Francisco

Route: DEN → SFO
Departs: 22:29
Flights: 264
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s F9 3439, check with Frontier Airlines.

F9 3439 sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 9 points worse than the national rate of 77.6%. The late ones land about 50 minutes behind schedule. That rests on 264 flights, with a median arrival right on schedule.

The national on-time rate over the same period is 77.6%, so F9 3439 runs 9 points behind the country as a whole. Across a thousand flights that is about 90 extra late arrivals.

On time

68.6%

Arrivals under 15 minutes late, of 258 completed flights

Avg delay

50 min

Across delayed arrivals only, not all flights

Cancelled

1.89%

National rate is 1.81%

1 hour+ late

8.1%

National rate is 8.1%

These figures cover 264 flights between July 2025 and June 2026. Beyond the headline rate, 8.1% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Schedule

When F9 3439 flies

F9 3439 is scheduled to leave Denver (DEN) at 22:29 local time and reach San Francisco (SFO) at 00:28. That slot held for 244 of the 264 scheduled departures in the data, so the figures below describe one steady operation rather than a number that moved around the clock.

Departs 22:29244 flights92.4%

Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.

Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.

A 22:29 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.5%, and F9 3439 runs level with that at 68.6%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.

Against the route

F9 3439 next to DEN to SFO

Every carrier on DEN to SFO combined arrived on time 65.8% of the time across 5,415 flights, so F9 3439 is 3 points ahead of it. Frontier flew 604 flights on the same city pair under all its flight numbers, including this one, and those ran 67.2% on time. Across its whole network Frontier Airlines managed 73.2%, which this flight trails by 5 points.

F9 3439 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
F9 3439thin sample	264	68.6%	50 min	1.89%	C
All Frontier Airlines on DEN–SFO	604	67.2%	55 min	0.83%	C+
All carriers on DEN–SFO	5,415	65.8%	61 min	0.48%	C+
Frontier Airlines, whole network	205,332	73.2%	84 min	1.85%	C

Across the year

F9 3439 quarter by quarter

F9 3439 did not run the same all year. Its best quarter was Jan–Mar 2026 at 84.1% on time and its weakest Jul–Sep 2025 at 44.8%, a swing of 39 points on roughly 66 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Jul–Sep 202559 flights44.8%
Oct–Dec 202566 flights76.9%
Jan–Mar 202665 flights84.1%
Apr–Jun 202674 flights66.7%

Scale runs 35% to 90%. Rows with fewer than 30 flights show a dash.

By weekday, F9 3439 did best on Friday at 76.0% on time and worst on Sunday at 57.4%. Each day rests on about 38 flights, so a gap of 19 points is worth noticing but could still narrow in another year.

Delay causes

Why F9 3439 runs late

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 4,079 reported delay minutes.

Carrier
36%
Late-arriving aircraft
34%
National Airspace System
23%
Extreme weather
6%

34% 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 4,079 reported delay minutes here, that single category outweighs weather by 5 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 4,079 delay minutes reported on F9 3439.

Cancellations sit at 1.89% against a national 1.81%, which is ordinary. Diversions add another 0.38%.

Connections and routes

What a delay on this flight costs

8.1% 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 about 50 minutes, which a normal layover absorbs.

The 967 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.

Every one of the 264 flights under F9 3439 in the data flew DEN to SFO. 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. 264 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 3439

For a booking, read F9 3439 as 68.6% on time with 1.89% cancelled over 264 flights. Those are rates from the past twelve months, not a forecast for any particular day.

Where to go next

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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures