Flight Reliability
F9 3439 · Frontier Airlines
Denver → San Francisco (DEN–SFO)
67
Usually Fine
WanderNerd Reliability Score
- 69%
- Arrive within 15 minutes
- 10 min
- Average arrival delay
- 2.0%
- Cancelled
- 0 min
- Median arrival delay
Based on 256 historical flights. Data through May 2026.
What the data says
Wednesdays have been rough.
F9 3439 arrived on time 84% of the time on Saturdays and just 45% on Wednesdays. That gap is worth planning around.
A bit behind the Frontier Airlines network.
F9 3439 arrived on time 69% of the time, versus 73% across the Frontier Airlines network.
Slipping a little lately.
F9 3439 arrived on time 78% of the time over the last three months in the data, compared with 81% in the three months before that.
The breakdown
- Mon71%(51 flights)
- Tue83%(12 flights)
- Wed45%(20 flights)
- Thu70%(50 flights)
- Fri78%(50 flights)
- Sat84%(19 flights)
- Sun56%(48 flights)
73%
May
Jun 50% → May 73% on time
| Month | On-time percentage | Flights |
|---|---|---|
| June 2025 | 50% | 22 |
| July 2025 | 33% | 21 |
| August 2025 | 50% | 20 |
| September 2025 | 59% | 17 |
| October 2025 | 78% | 18 |
| November 2025 | 74% | 19 |
| December 2025 | 79% | 28 |
| January 2026 | 77% | 17 |
| February 2026 | 89% | 18 |
| March 2026 | 86% | 28 |
| April 2026 | 75% | 20 |
| May 2026 | 73% | 22 |
- Departures on time
- 62%
- Diverted
- 0.4%
- Flights flown
- 250
- Months covered
- 12
Same route, other flights
Keep nerding
Based on 256 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.