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Flight Reliability

UA 3639 · United Airlines

This number covered several routes in this period.

One number, several routes.

Airlines reuse flight numbers, and UA 3639 moved between routes during this period. Numbers below combine all of them, so treat them as background, not a verdict. For a cleaner answer, check the route you are actually flying.

Combined across all its routes

76%
Arrive within 15 minutes
10 min
Average arrival delay
4.3%
Cancelled
7 min early
Median arrival delay

Based on 326 historical flights. Data through May 2026.

The breakdown

On-time by weekday
  • Mon73%(44 flights)
  • Tue82%(45 flights)
  • Wed76%(45 flights)
  • Thu73%(44 flights)
  • Fri75%(47 flights)
  • Sat81%(41 flights)
  • Sun76%(45 flights)
On-time by departure window
  • 3–6 AM—(1 flights)
  • 6–9 AM83%(88 flights)
  • 9 AM–12 PM—(3 flights)
  • 12–3 PM74%(144 flights)
  • 3–6 PM74%(23 flights)
  • 6–9 PM—(3 flights)
  • 9 PM–12 AM71%(49 flights)
On-time trend by month
88%
May

Jun 79% → May 88% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202579%14
July 202552%25
August 202586%28
September 202577%26
October 202594%31
November 202577%26
December 202568%31
February 202667%24
March 202661%31
April 202683%30
May 202688%40
Departures on time
82%
Diverted
0.3%
Flights flown
311
Months covered
12

Keep nerding

Based on 326 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.