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Route Reliability

Washington → St. Louis

IAD–STL · 696 miles · Washington Dulles International Airport to St. Louis Lambert International Airport

76
Usually Fine
WanderNerd Reliability Score
76%
Arrive within 15 minutes
18 min
Average arrival delay
0.6%
Cancelled
718
Flights in the data

Data through May 2026.

United Airlines is the only airline in this data on this route, arriving on time 76% of the time across 718 flights. No comparison to make.

What the data says

Morning flights do better here.

IAD–STL flights departing between 9 AM–12 PM arrived on time 88% of the time, versus 69% between 3–6 PM.

Monday is the weak spot.

IAD–STL flights arrived on time 81% of the time on Tuesdays. On Mondays: 69%.

Trending in the right direction.

IAD–STL flights arrived on time 81% of the time over the last three months in the data, compared with 72% in the three months before that.

Best historical flights

Ranked by on-time arrivals, minimum 100 flights. Past performance, not a promise.

Top flights by on-time rate

More flights on this route

The breakdown

On-time by weekday
  • Mon69%(101 flights)
  • Tue81%(101 flights)
  • Wed77%(100 flights)
  • Thu81%(104 flights)
  • Fri71%(104 flights)
  • Sat80%(97 flights)
  • Sun74%(104 flights)
On-time by departure window
  • 6–9 AM81%(285 flights)
  • 9 AM–12 PM88%(65 flights)
  • 3–6 PM69%(341 flights)
  • 6–9 PM85%(20 flights)
On-time trend by month
79%
May

Jun 68% → May 79% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202568%60
July 202571%62
August 202573%62
September 202586%58
October 202582%51
November 202578%60
December 202563%62
January 202666%59
February 202686%55
March 202677%62
April 202688%59
May 202679%61

Same trip, other airports

Keep nerding

Based on 718 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.