Historical on-time performance
Washington to San Juan
1,571 miData through Dec 2025Source: US DOT · BTS
Flights on IAD–SJU arrive on time 79% of the time over the last 12 months.
On-time rate79%arrived within 15 min
p90 delay30 min1 in 10 flights is worse (tail risk)
Cancelled0.2%of scheduled flights
based on 525 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).
By airline
How each carrier compares
- United AirlinesOn-time79%Medianon timep9030 minCancel0.2%Flights525
Why flights run late
Delay causes
- Airline25%
- Weather10%
- Air traffic (NAS)43%
- Late aircraft22%
- Security0%
Most delay minutes here are attributed to Air traffic (NAS).
Over time
On-time trend
By season
On-time rate by month
When to fly
Best time to fly IAD → SJU
All airlines · rolling 36 months (2023-01 .. 2025-12).
Best time of day
Mornings are the most reliable time of day to fly this route — 88% on time.
- Mornings88% on time · p90 15 min · 1,044 flights
- Evenings69% on time · p90 55 min · 294 flights
- Middays46% on time · p90 180 min · 78 flights · limited
Best day of week
On-time rates are fairly even by day on this route — ranging from 76% to 87% on time.
- Fridays87% on time · p90 20 min · 183 flights · limited
- Wednesdays86% on time · p90 15 min · 172 flights · limited
- Mondays82% on time · p90 35 min · 181 flights · limited
- Tuesdays81% on time · p90 25 min · 186 flights · limited
- Thursdays79% on time · p90 35 min · 197 flights · limited
- Saturdays79% on time · p90 30 min · 256 flights
- Sundays76% on time · p90 55 min · 269 flights
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