Carrier route record

F9GRR→DEN

Frontier Airlines · Grand Rapids to Denver

Flights: 147
Period: September 2025 to August 2026
Share of route: 12%
Carriers: 4

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

Frontier on GRR to DEN lands a B+, level with the national rate of 77.3%. Roughly one flight in four arrives 15 minutes late or worse, and those flights are late by close to two hours on average. That rests on 147 flights, with a median arrival 12 minutes early.

The US average over the same twelve months is 77.3%, 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

77.2%

Arrivals under 15 minutes late, of 145 completed flights

Avg delay

107 min

Across delayed arrivals only, not all flights

Cancelled

0.00%

National rate is 1.89%

Whole route

76.1%

Every carrier on GRR to DEN, 1,234 flights

These figures cover 147 flights between September 2025 and August 2026. Beyond the headline rate, 11.7% of arrivals land a full hour or more behind schedule, against 8.3% nationally.

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Carrier by carrier

Frontier against every carrier on GRR to DEN

Frontier flew 147 of the 1,234 flights on GRR to DEN, about 12% of it. Its 77.2% on time is about level with the route as a whole at 76.1%. Ranked by on-time rate it is number three of four carriers on the route, where the range runs from SkyWest at 100.0% to Southwest at 72.5%. 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	727	77.6%	81 min	0.55%	B+
Frontier Airlines (this page)thin sample	147	77.2%	107 min	0.00%	B+
Southwest Airlinesthin sample	359	72.5%	56 min	0.28%	C+

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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 147 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 77.2% is the reliable figure here.

Across the year

Frontier on GRR to DEN through the year

Jul–Sep 202520 flights—
Oct–Dec 202536 flights69.4%
Jan–Mar 20263 flights—
Apr–Jun 202643 flights85.7%
Jul–Sep 202645 flights77.3%

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 77.2% on time across 147 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 Oct–Dec 2025 at 69.4%, a swing of 16 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 91.4% on time and Monday the weakest at 71.4%, a spread of 20 points.

Arrival by arrival

How late Frontier on GRR to DEN runs when it is late

Frontier on GRR to DEN often beats the schedule: 62 of 145 completed flights, 43%, arrived 15 minutes or more early. When Frontier on GRR to DEN is late it tends to be very late: 17 of its 33 late arrivals were an hour or more behind, and 7 were two hours or more.

15+ min early62 flights42.8%
Within 15 min50 flights34.5%
15–29 min late10 flights6.9%
30–59 min late6 flights4.1%
1–2 hours late10 flights6.9%
2+ hours late7 flights4.8%

Scale runs 0% to 100%.

Share of 145 completed flights by arrival against schedule.

8 of 34 late departures made up the time and arrived on time, 24% of them. 7 flights left on time and still arrived late.

The worst days

Worst days for Frontier on GRR to DEN

The latest arrival of the period was on 18 September 2025, 14 hours 37 minutes behind schedule; most of its delay minutes were filed as extreme weather. Three of the five worst days fell in August 2026.

The latest arrivals of Frontier on GRR to DEN in the period
Date	Arrived late by	Largest filed cause
18 September 2025	14 hours 37 minutes	Extreme weather
12 October 2025	4 hours 26 minutes	Late-arriving aircraft
13 August 2026	4 hours 25 minutes	National Airspace System
17 August 2026	4 hours 8 minutes	Late-arriving aircraft
14 August 2026	3 hours 37 minutes	National Airspace System

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 3,522 reported delay minutes.

Late-arriving aircraft
38%
National Airspace System
33%
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 4.1 times the usual weather exposure. The split is drawn from 3,522 reported delay minutes.

38% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 3,522 reported delay minutes here, that single category outweighs weather by 2 to one.

Cancellations are rare at 0.00%, below the national 1.89% 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

11.7% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection 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.

The return leg is a different operation and performs like one: it runs 85.1% on time across 148 flights, 8 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 8 points of difference.

One caution: this is a thin sample. 147 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. 147 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 77.2% 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, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures