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Flight Reliability

UA 4527 · United Airlines

Washington → St. Louis (IAD–STL)

64
A Little Dicey
WanderNerd Reliability Score
70%
Arrive within 15 minutes
30 min
Average arrival delay
0.5%
Cancelled
8 min early
Median arrival delay

Based on 365 historical flights. Data through May 2026.

What the data says

The late departure is the smart one here.

UA 4527 departing between 6–9 PM arrived on time 85% of the time, versus 69% between 3–6 PM.

Friday is doing you no favors.

UA 4527 arrived on time 78% of the time on Saturdays and just 58% on Fridays. That gap is worth planning around.

A bit behind the IAD–STL route.

UA 4527 arrived on time 70% of the time, versus 76% across the IAD–STL route.

Lagging the United Airlines network.

UA 4527 arrived on time 70% of the time, versus 79% across the United Airlines network.

The breakdown

On-time by weekday
  • Mon59%(51 flights)
  • Tue77%(52 flights)
  • Wed73%(52 flights)
  • Thu75%(52 flights)
  • Fri58%(52 flights)
  • Sat78%(50 flights)
  • Sun71%(52 flights)
On-time by departure window
  • 3–6 PM69%(341 flights)
  • 6–9 PM85%(20 flights)
On-time trend by month
74%
May

Jun 53% → May 74% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202553%30
July 202558%31
August 202568%31
September 202580%30
October 202581%31
November 202570%30
December 202561%31
January 202659%29
February 202685%27
March 202671%31
April 202683%29
May 202674%31
Departures on time
70%
Diverted
0.5%
Flights flown
361
Months covered
12

Same route, other flights

Keep nerding

Based on 365 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.