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Flight Reliability

F9 4637 · Frontier Airlines

Cleveland → Denver (CLE–DEN)

56
A Little Dicey
WanderNerd Reliability Score
61%
Arrive within 15 minutes
20 min
Average arrival delay
1.9%
Cancelled
2 min
Median arrival delay

Based on 155 historical flights. Data through May 2026.

What the data says

The 12–3 PM departure wins.

F9 4637 departing between 12–3 PM arrived on time 92% of the time, versus 56% between 6–9 PM.

Wednesdays have been rough.

F9 4637 arrived on time 74% of the time on Saturdays and just 40% on Wednesdays. That gap is worth planning around.

Well behind the CLE–DEN route.

F9 4637 arrived on time 61% of the time, versus 81% across the CLE–DEN route.

Lagging the Frontier Airlines network.

F9 4637 arrived on time 61% of the time, versus 73% across the Frontier Airlines network.

The breakdown

On-time by weekday
  • Mon54%(24 flights)
  • Tue54%(13 flights)
  • Wed40%(10 flights)
  • Thu59%(32 flights)
  • Fri68%(22 flights)
  • Sat74%(19 flights)
  • Sun66%(32 flights)
On-time by departure window
  • 12–3 PM92%(12 flights)
  • 3–6 PM77%(13 flights)
  • 6–9 PM56%(125 flights)
  • 9 PM–12 AM—(2 flights)
On-time trend by month
63%
Mar

Jun 29% → Mar 63% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202529%14
July 202553%17
August 202582%17
September 202556%16
October 202553%15
November 202582%17
December 202533%12
February 202692%13
March 202663%16
Departures on time
59%
Diverted
0%
Flights flown
152
Months covered
11

Same route, other flights

Keep nerding

Based on 155 historical flights, because apparently we checked. Historical flight data: U.S. Bureau of Transportation Statistics, June 2025 – May 2026. Data through May 2026. How we calculate this.