Route reliability record
GRR→DEN
Grand Rapids to Denver
- Flights
- 1,238
- Period
- July 2025 to June 2026
- Distance
- 1,015 mi
- Carriers
- 4
This route lands a B+, about a point better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 1,238 GRR to DEN flights, with a median arrival 6 minutes early.
Best time to fly GRR to DEN: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 89.7% of the time and Tuesday flights 81.4%, against 78.4% for the route overall.
The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
78.4%
Arrivals under 15 minutes late, of 1,228 completed flights
Avg delay
72 min
Across delayed arrivals only, not all flights
Cancelled
0.40%
National rate is 1.81%
Best carrier
United
79.7% on time across 728 flights
These figures cover 1,238 flights between July 2025 and June 2026. The median arrival is 6 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
Which airline is most reliable on GRR to DEN
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.
| 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 Airlinesthin sample | 146 | 74.5% | 96 min | 0.00% | C+ |
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 36 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am59 flights89.7%
- 8am–11am498 flights83.8%
- 11am–2pm51 flights88.2%
- 2pm–5pm455 flights74.2%
- 5pm–8pm52 flights53.8%
- 8pm–5am123 flights73.0%
Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 53.8% on time, against 89.7% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8am–11am window is the busiest, with 498 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 33 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
January is the weak month at 57.3% on time, against 90.1% in October. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. July was the busiest month here, with 122 flights.
Across the week, Tuesday is the strongest day at 81.4% on time and Monday the weakest at 74.7%. 7 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
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 19,000 reported delay minutes.
- 35%Carrier
- 31%National Airspace System
- 27%Late-arriving aircraft
- 6%Extreme weather
The largest share of delay minutes, 35%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 6,702 of the 19,000 delay minutes reported here. The split is drawn from 18,965 reported delay minutes.
Cancellations are rare at 0.40%, 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 actually costs
6.4% 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 a little over an hour, which a normal layover absorbs.
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 75.3% on time across 1,239 flights, 3 points below 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 3 points of difference.
The sample behind these figures is 1,238 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
Work out the risk of missing a connection in DEN after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. October runs 90.1% on time and January 57.3%, a swing of 33 points. If the dates move at all, move them out of January before you think about anything else. 1,228 completed flights over 12 months sit behind that.
Common questions
GRR to DEN questions
How often is GRR to DEN delayed?
About one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 21.6% of the 1,238 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
How reliable is GRR to DEN compared with the rest of the country?
78.4% of flights arrive on time here against a national 77.6%, a difference of about a point in its favour. That is worth a B+ on this site's grading scale.
What time of day has the fewest delays on GRR to DEN?
The 5am–8am departure window is the strongest at 89.7% on time. The 5pm–8pm window is the weakest at 53.8%, 36 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are January delays on GRR to DEN?
January is the weakest month at 57.3% on time, compared with 90.1% in October. Across the year that is 33 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- DEN to GRR — the return legseparate record
- Denver International (DEN) delay statistics
- United Airlines on GRR to DEN79.7%
- Southwest Airlines on GRR to DEN77.3%
- Frontier Airlines on GRR to DEN74.5%
- GRR to ORD, a related route68.3%
- PHX to DEN, a related route77.2%
- GRR to DTW, a related route78.2%
- SkyWest Airlines on-time record100.0%
- United Airlines on-time record79.7%
- Southwest Airlines on-time record77.3%
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. GRR to DEN and DEN to GRR are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.