Carrier route record

F9GRR→DEN

Frontier Airlines · Grand Rapids to Denver

Flights: 146
Period: July 2025 to June 2026
Share of route: 12%
Carriers: 4

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

Frontier on GRR to DEN sits in the middle of the pack with a C+. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.6%. The late ones land an hour and a half behind schedule. That rests on 146 flights, with a median arrival 10 minutes early.

The US average over the same twelve months is 77.6%, so there is little to separate Frontier on GRR to DEN from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

74.5%

Arrivals under 15 minutes late, of 145 completed flights

Avg delay

96 min

Across delayed arrivals only, not all flights

Cancelled

0.00%

National rate is 1.81%

Whole route

78.4%

Every carrier on GRR to DEN, 1,238 flights

These figures cover 146 flights between July 2025 and June 2026. Beyond the headline rate, 13.1% 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.

Carrier by carrier

Frontier against every carrier on GRR to DEN

Frontier flew 146 of the 1,238 flights on GRR to DEN, about 12% of it. Its 74.5% on time is 4 points worse than the route as a whole, which runs 78.4%. Ranked by on-time rate it is last of four carriers on the route, where the range runs from SkyWest at 100.0% to Frontier at 74.5%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.

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.

On-time performance by carrier on GRR to DEN
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlinesthin sample	1	100.0%	—	0.00%	A+
United Airlines	728	79.7%	76 min	0.55%	B+
Southwest Airlinesthin sample	363	77.3%	53 min	0.28%	B+
Frontier Airlines (this page)thin sample	146	74.5%	96 min	0.00%	C+

Departure window

When Frontier runs best on this route

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 146 flights.

There are not enough flights in each departure window to split Frontier's GRR to DEN record by time of day without the percentages moving on noise. The headline rate of 74.5% is the reliable figure here.

Across the year

Frontier on GRR to DEN through the year

Jul–Sep 202564 flights68.8%
Oct–Dec 202536 flights69.4%
Jan–Mar 20263 flights—
Apr–Jun 202643 flights85.7%

Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 74.5% on time across 146 flights.

Frontier on GRR to DEN did not run the same all year. Its best quarter was Apr–Jun 2026 at 85.7% on time and its weakest Jul–Sep 2025 at 68.8%, a swing of 17 points on roughly 49 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.

Across the week, Friday is the strongest day at 85.7% on time and Monday the weakest at 76.5%. 9 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Frontier runs late on this route

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 3,562 reported delay minutes.

National Airspace System
37%
Late-arriving aircraft
35%
Extreme weather
25%
Carrier
4%

Extreme weather accounts for 25% 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 4.0 times the usual weather exposure. The split is drawn from 3,562 reported delay minutes.

35% 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 3,562 reported delay minutes here, that single category outweighs weather by 1 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.

Cancellations are rare at 0.00%, below the national 1.81% and low enough to earn the plus on the grade. Almost no flights are called off; the risk here is arriving late, not not arriving.

Connections and stage length

What a delay here costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 13.1% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.

The 1,015 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 is a different operation and performs like one: it runs 87.1% on time across 147 flights, 13 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 13 points of difference.

One caution: this is a thin sample. 146 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 GRR to DEN

Put together: treat all of this as provisional. 146 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 74.5% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 145 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