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Flight Reliability

UA 4335 · United Airlines

Washington → Buffalo (IAD–BUF)96% of its flights flew this route. The rest (IAD–PHL, PIT–IAD) are included in these numbers.

85
Pretty Reliable
WanderNerd Reliability Score
83%
Arrive within 15 minutes
5 min
Average arrival delay
1.6%
Cancelled
9 min early
Median arrival delay

Based on 307 historical flights. Data through May 2026.

What the data says

Saturday is the weak spot.

UA 4335 arrived on time 89% of the time on Wednesdays. On Saturdays: 78%.

A bit ahead of the IAD–BUF route.

UA 4335 arrived on time 83% of the time, versus 78% across the IAD–BUF route.

A bit ahead of the United Airlines network.

UA 4335 arrived on time 83% of the time, versus 79% across the United Airlines network.

Trending in the right direction.

UA 4335 arrived on time 89% of the time over the last three months in the data, compared with 78% in the three months before that.

The breakdown

On-time by weekday
  • Mon83%(46 flights)
  • Tue79%(43 flights)
  • Wed89%(45 flights)
  • Thu87%(47 flights)
  • Fri83%(41 flights)
  • Sat78%(37 flights)
  • Sun81%(43 flights)
On-time by departure window
  • 12–3 PM83%(296 flights)
  • 3–6 PM—(6 flights)
On-time trend by month
100%
May

Jun 77% → May 100% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202577%30
July 202590%31
August 202573%26
September 202595%21
October 202584%31
November 202579%29
December 202579%14
January 202666%29
February 202691%11
March 202678%23
April 202689%26
May 2026100%31
Departures on time
85%
Diverted
0%
Flights flown
302
Months covered
12

Same route, other flights

Keep nerding

Based on 307 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.