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Flight Reliability

UA 641 · United Airlines

Washington → Boston (IAD–BOS)88% of its flights flew this route. The rest (ATL–IAD, SNA–DEN) are included in these numbers.

96
Nerd Approved
WanderNerd Reliability Score
92%
Arrive within 15 minutes
5 min early
Average arrival delay
1.0%
Cancelled
10 min early
Median arrival delay

Based on 390 historical flights. Data through May 2026.

What the data says

Mornings have a slight edge.

Departures between 3–6 AM arrived on time 95% of the time, against 92% between 9 AM–12 PM.

Monday is the weak spot.

UA 641 arrived on time 95% of the time on Thursdays. On Mondays: 88%.

Well ahead of the IAD–BOS route.

UA 641 arrived on time 92% of the time, versus 76% across the IAD–BOS route.

Better than the United Airlines network average.

UA 641 arrived on time 92% of the time, versus 79% across the United Airlines network.

The breakdown

On-time by weekday
  • Mon88%(59 flights)
  • Tue91%(46 flights)
  • Wed94%(47 flights)
  • Thu95%(61 flights)
  • Fri89%(61 flights)
  • Sat94%(52 flights)
  • Sun95%(60 flights)
On-time by departure window
  • 3–6 AM95%(43 flights)
  • 6–9 AM92%(233 flights)
  • 9 AM–12 PM92%(107 flights)
  • 3–6 PM—(3 flights)
On-time trend by month
95%
May

Jun 93% → May 95% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202593%30
July 202587%31
August 202587%31
September 202593%30
October 202590%31
November 202597%30
December 202587%31
January 202688%16
February 2026100%21
March 202697%32
April 202692%47
May 202695%56
Departures on time
92%
Diverted
0%
Flights flown
386
Months covered
12

Same route, other flights

Keep nerding

Based on 390 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.