Skip to content
WanderNerd
Check a flight

Flight Reliability

UA 4427 · United Airlines

Washington → St. Louis (IAD–STL)93% of its flights flew this route. The rest (ORD–ABE, ORD–STL) are included in these numbers.

87
Pretty Reliable
WanderNerd Reliability Score
83%
Arrive within 15 minutes
8 min
Average arrival delay
0.6%
Cancelled
13 min early
Median arrival delay

Based on 362 historical flights. Data through May 2026.

What the data says

Morning flights do better here.

UA 4427 departing between 9 AM–12 PM arrived on time 92% of the time, versus 73% between 9 PM–12 AM.

Sunday scaries are real for this one.

UA 4427 arrived on time 88% of the time on Tuesdays. On Sundays: 77%.

A bit ahead of the IAD–STL route.

UA 4427 arrived on time 83% of the time, versus 76% across the IAD–STL route.

A bit ahead of the United Airlines network.

UA 4427 arrived on time 83% of the time, versus 79% across the United Airlines network.

The breakdown

On-time by weekday
  • Mon80%(50 flights)
  • Tue88%(51 flights)
  • Wed80%(51 flights)
  • Thu87%(52 flights)
  • Fri85%(52 flights)
  • Sat84%(51 flights)
  • Sun77%(52 flights)
On-time by departure window
  • 6–9 AM82%(287 flights)
  • 9 AM–12 PM92%(60 flights)
  • 3–6 PM—(1 flights)
  • 9 PM–12 AM73%(11 flights)
On-time trend by month
93%
May

Jun 83% → May 93% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202583%30
July 202584%31
August 202577%31
September 202593%28
October 202581%31
November 202587%30
December 202565%31
January 202672%29
February 202685%27
March 202684%31
April 202693%30
May 202693%30
Departures on time
84%
Diverted
0.3%
Flights flown
359
Months covered
12

Same route, other flights

Keep nerding

Based on 362 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.