Flight Reliability
F9 4521 · Frontier Airlines
Denver → Burbank (DEN–BUR)
87
Pretty Reliable
WanderNerd Reliability Score
- 79%
- Arrive within 15 minutes
- 0 min
- Average arrival delay
- 0%
- Cancelled
- 11 min early
- Median arrival delay
Based on 52 historical flights. Data through May 2026.
What the data says
Sunday scaries are real for this one.
F9 4521 arrived on time 83% of the time on Thursdays. On Sundays: 74%.
A bit ahead of the DEN–BUR route.
F9 4521 arrived on time 79% of the time, versus 74% across the DEN–BUR route.
A bit ahead of the Frontier Airlines network.
F9 4521 arrived on time 79% of the time, versus 73% across the Frontier Airlines network.
The breakdown
- Mon—(0 flights)
- Tue—(0 flights)
- Wed—(1 flights)
- Thu83%(24 flights)
- Fri—(0 flights)
- Sat—(0 flights)
- Sun74%(27 flights)
- Departures on time
- 81%
- Diverted
- 0%
- Flights flown
- 52
- Months covered
- 6
Same route, other flights
Keep nerding
Based on 52 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.