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Flight Reliability

UA 4339 · United Airlines

Washington → ROA (IAD–ROA)90% of its flights flew this route. The rest (SYR–IAD, IAH–CRP) are included in these numbers.

68
Usually Fine
WanderNerd Reliability Score
78%
Arrive within 15 minutes
13 min
Average arrival delay
3.4%
Cancelled
6 min early
Median arrival delay

Based on 353 historical flights. Data through May 2026.

What the data says

The 3–6 PM departure wins.

UA 4339 departing between 3–6 PM arrived on time 80% of the time, versus 52% between 9 AM–12 PM.

Mondays have been rough.

UA 4339 arrived on time 86% of the time on Saturdays and just 71% on Mondays. That gap is worth planning around.

Keep a backup plan handy.

UA 4339 was cancelled 3.4% of the time. Typical for U.S. flights is around 1–2%.

Trending in the right direction.

UA 4339 arrived on time 82% of the time over the last three months in the data, compared with 70% in the three months before that.

The breakdown

On-time by weekday
  • Mon71%(51 flights)
  • Tue80%(45 flights)
  • Wed78%(45 flights)
  • Thu82%(49 flights)
  • Fri71%(49 flights)
  • Sat86%(50 flights)
  • Sun78%(50 flights)
On-time by departure window
  • 6–9 AM70%(10 flights)
  • 9 AM–12 PM52%(25 flights)
  • 3–6 PM80%(284 flights)
  • 6–9 PM80%(20 flights)
On-time trend by month
79%
May

Jun 78% → May 79% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202578%27
July 202565%26
August 202581%31
September 202580%30
October 202587%31
November 202583%29
December 202571%31
January 202668%22
February 202671%24
March 202669%29
April 202697%30
May 202679%29
Departures on time
80%
Diverted
0.6%
Flights flown
339
Months covered
12

Same route, other flights

Keep nerding

Based on 353 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.