Flight Reliability
F9 3937 · Frontier Airlines
San Juan → Hartford (SJU–BDL)
74
Usually Fine
WanderNerd Reliability Score
- 76%
- Arrive within 15 minutes
- 6 min
- Average arrival delay
- 2.3%
- Cancelled
- 8 min early
- Median arrival delay
Based on 172 historical flights. Data through May 2026.
What the data says
The 6–9 AM departure wins.
F9 3937 departing between 6–9 AM arrived on time 79% of the time, versus 54% between 12–3 AM.
Mondays have been rough.
F9 3937 arrived on time 85% of the time on Saturdays and just 58% on Mondays. That gap is worth planning around.
A bit ahead of the SJU–BDL route.
F9 3937 arrived on time 76% of the time, versus 72% across the SJU–BDL route.
Recent months have been rougher.
F9 3937 arrived on time 71% of the time over the last three months in the data, compared with 83% in the three months before that.
The breakdown
- Mon58%(24 flights)
- Tue81%(16 flights)
- Wed76%(21 flights)
- Thu77%(26 flights)
- Fri80%(25 flights)
- Sat85%(26 flights)
- Sun73%(30 flights)
- 12–3 AM54%(13 flights)
- 6–9 AM79%(103 flights)
- 9 AM–12 PM—(9 flights)
- 12–3 PM—(4 flights)
- 3–6 PM69%(39 flights)
54%
Apr
Jun 83% → Apr 54% on time
| Month | On-time percentage | Flights |
|---|---|---|
| June 2025 | 83% | 23 |
| July 2025 | 67% | 24 |
| August 2025 | 76% | 29 |
| December 2025 | 90% | 20 |
| January 2026 | 82% | 11 |
| February 2026 | 79% | 19 |
| March 2026 | 80% | 20 |
| April 2026 | 54% | 13 |
- Departures on time
- 83%
- Diverted
- 0%
- Flights flown
- 168
- Months covered
- 10
Same route, other flights
Keep nerding
Based on 172 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.