St Louis Lambert International in April 2026

78.5%departed on time

BTS: A flight is counted as on time if it arrived less than 15 minutes after its scheduled time. Only carriers with at least 0.5 percent of domestic scheduled passenger revenue report.

In April 2026, reporting carriers scheduled 5,156 domestic departures from St Louis Lambert International (STL). 78.5% left less than 15 minutes late and 80.0% reached their destination on time; 0.8% were cancelled.

Nationally that month, 79.1% of flights departed on time and 78.9% arrived on time, so STL departures were 0.6 points below the national departure figure.

A year earlier, in April 2025, the airport had 5,439 departures with 79.9% leaving on time: a change of −1.4 points, with flights down 5%.

Flights arriving at STL that month were on time 79.9% of the time (5,155 scheduled arrivals).

Of the delay minutes that carriers assigned to a BTS cause category that month, late-arriving aircraft 45%, air carrier 28% and national aviation system 21%.

On time 80.0%
Arrived 15+ minutes late 19.0%
Cancelled 0.8%
Diverted 0.2%

Every scheduled departure from STL in April 2026, judged by arrival at the destination.

April 2026 against a year earlier, the airport's year and the nation

Measure	Apr 2026	Apr 2025	STL, 12 months to Jul 2026	All reported flights, Apr 2026
Departed on time	78.5%	79.9%	74.1%	79.1%
Arrived on time	80.0%	79.9%	76.8%	78.9%
Cancelled	0.8%	0.8%	1.3%	0.9%
Average departure delay (late minutes only)	14.4 min	13.6 min	17.6 min	14.5 min
Scheduled departures a day	172	181	174	19,931
Scheduled departures	5,156	5,439	63,318	597,919

Airlines that month

Reporting carrier	Flights	Share	On time	Avg arrival delay	Cancelled
WN Southwest Airlines	3,162	61%	79.5%	3.8 min	0.2%
AA American Airlines	524	10%	82.3%	5.9 min	1.3%
DL Delta Air Lines	422	8%	87.9%	-3.8 min	1.2%
YX Republic Airline	287	6%	81.9%	-4.1 min	1.0%
OO SkyWest Airlines	228	4%	65.8%	25.3 min	3.9%
MQ Envoy Air	149	3%	74.5%	28.1 min	2.0%
UA United Airlines	142	3%	83.1%	0.8 min	2.1%
F9 Frontier Airlines	97	2%	74.2%	10.9 min	2.1%
OH PSA Airlines	85	2%	81.2%	1.8 min	1.2%
AS Alaska Airlines	60	1%	91.7%	-2.4 min	3.3%

Busiest routes that month

Route	Cities	Flights	On time	Avg arrival delay	Cancelled
STL–ATL	St. Louis to Atlanta	299	84.3%	1.7 min	2.0%
STL–ORD	St. Louis to Chicago	294	67.7%	29.5 min	5.1%
STL–DEN	St. Louis to Denver	286	79.0%	4.2 min	0.7%
STL–LGA	St. Louis to New York	249	76.3%	1.9 min	0.4%
STL–MCO	St. Louis to Orlando	228	85.5%	-1.4 min	0.4%
STL–PHX	St. Louis to Phoenix	207	79.7%	11.9 min	0.0%
STL–DCA	St. Louis to Washington	193	81.3%	0.8 min	0.0%
STL–MSP	St. Louis to Minneapolis	183	82.5%	-0.4 min	0.0%
STL–DFW	St. Louis to Dallas/Fort Worth	180	75.6%	8.4 min	2.2%
STL–DTW	St. Louis to Detroit	167	86.2%	-0.7 min	0.0%
STL–LAS	St. Louis to Las Vegas	167	70.1%	12.8 min	0.6%
STL–DAL	St. Louis to Dallas	158	78.5%	1.0 min	1.3%

By scheduled departure hour

On-time share:under 62%6270768288% and over

Share of departures that left less than 15 minutes late, by scheduled hour (local time), April 2026.

Delay causes

BTS cause category	Share of delay minutes	National, Apr 2026	Minutes
Air carrier	28.0%	33.5%	17,925
Late-arriving aircraft	45.2%	40.4%	28,888
National Aviation System	20.8%	21.0%	13,318
Extreme weather	5.9%	5.0%	3,775
Security	0.1%	0.1%	51

63,957 delay minutes on 981 flights that arrived 15 or more minutes late and carried a cause report. Carriers assign the categories; see what each category means.

Questions and answers

How many flights left STL on time in April 2026?

78.5% of 5,156 scheduled domestic departures left less than 15 minutes late, and 80.0% reached their destination on time. The national figures that month were 79.1% and 78.9%.

How does that compare with a year earlier?

In April 2025, 79.9% of 5,439 departures left on time and 0.8% were cancelled, against 78.5% and 0.8% in April 2026.

Provenance

Source: Bureau of Transportation Statistics, Reporting Carrier On-Time Performance, file for April 2026; public domain. Domestic scheduled flights by reporting carriers, totals and averages only. The site's data runs through July 2026. Full record for STL · methodology · corrections.