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Flight Reliability

F9 4639 · Frontier Airlines

Cleveland → Denver (CLE–DEN)

71
Usually Fine
WanderNerd Reliability Score
68%
Arrive within 15 minutes
12 min
Average arrival delay
0.8%
Cancelled
5 min early
Median arrival delay

Based on 127 historical flights. Data through May 2026.

What the data says

The 12–3 PM departure wins.

F9 4639 departing between 12–3 PM arrived on time 84% of the time, versus 47% between 6–9 PM.

Wednesdays have been rough.

F9 4639 arrived on time 78% of the time on Fridays and just 62% on Wednesdays. That gap is worth planning around.

Lagging the CLE–DEN route.

F9 4639 arrived on time 68% of the time, versus 81% across the CLE–DEN route.

A bit behind the Frontier Airlines network.

F9 4639 arrived on time 68% of the time, versus 73% across the Frontier Airlines network.

The breakdown

On-time by weekday
  • Mon65%(17 flights)
  • Tue68%(19 flights)
  • Wed62%(13 flights)
  • Thu64%(22 flights)
  • Fri78%(18 flights)
  • Sat71%(17 flights)
  • Sun65%(20 flights)
On-time by departure window
  • 6–9 AM—(5 flights)
  • 9 AM–12 PM—(2 flights)
  • 12–3 PM84%(51 flights)
  • 3–6 PM66%(29 flights)
  • 6–9 PM47%(38 flights)
  • 9 PM–12 AM—(1 flights)
On-time trend by month
90%
May

Jun 36% → May 90% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202536%14
July 202543%14
August 202536%11
April 202688%17
May 202690%31
Departures on time
68%
Diverted
0%
Flights flown
126
Months covered
12

Same route, other flights

Keep nerding

Based on 127 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.