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Flight Reliability

F9 4391 · Frontier Airlines

Detroit → Phoenix (DTW–PHX)

50
A Little Dicey
WanderNerd Reliability Score
66%
Arrive within 15 minutes
39 min
Average arrival delay
2.4%
Cancelled
2 min early
Median arrival delay

Based on 82 historical flights. Data through May 2026.

What the data says

The 12–3 PM departure wins.

F9 4391 departing between 12–3 PM arrived on time 75% of the time, versus 64% between 6–9 PM.

Saturdays have been rough.

F9 4391 arrived on time 83% of the time on Thursdays and just 46% on Saturdays. That gap is worth planning around.

Lagging the DTW–PHX route.

F9 4391 arrived on time 66% of the time, versus 78% across the DTW–PHX route.

A bit behind the Frontier Airlines network.

F9 4391 arrived on time 66% of the time, versus 73% across the Frontier Airlines network.

The breakdown

On-time by weekday
  • Mon56%(16 flights)
  • Tue—(6 flights)
  • Wed—(4 flights)
  • Thu83%(12 flights)
  • Fri75%(16 flights)
  • Sat46%(11 flights)
  • Sun53%(15 flights)
On-time by departure window
  • 12–3 PM75%(24 flights)
  • 3–6 PM—(5 flights)
  • 6–9 PM64%(42 flights)
  • 9 PM–12 AM—(9 flights)
On-time trend by month
71%
Feb

Sep 64% → Feb 71% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
September 202564%11
October 202572%18
November 202570%10
December 202555%11
February 202671%17
Departures on time
73%
Diverted
0%
Flights flown
80
Months covered
8

Same route, other flights

Keep nerding

Based on 82 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.