ATIS Alerts Smart Flight Search
Find the flight least likely to be delayed
BetaWe rank real flight numbers by how often they flew and arrived on time over the last 12 months, adjusted for your travel month and departure time, then check nearby airports and calmer connections. US airlines and airports.
STL → BWI
St Louis to Baltimore: 1,288 nonstop flights a year
On time (12 months)
81%
Cancelled
1.2%
avg delay 13 min
Best time to leave
Before 9 AM
96% on time vs 65% 3 to 6 PM
Most reliable airline
Southwest
80% chance on time
Lowest nonstop fare seen in the next two months: $597 (Southwest 1057 on 2026-10-21). Fares open on our travel partner (Aviasales). Pick the flight number you chose here.
Most reliable nonstop flights
Ranked by the chance the flight operates and arrives within 15 minutes of schedule, from Jun 2025 to May 2026 records.
#1 · Southwest 4440
5:00 AM → 8:05 AM2h 05m nonstop
Local times, typical schedule. Last flown 2026-05-31.
93%
chance on time
- On time (history)
- 96%
- Cancelled
- 0.0%
- Avg arrival delay
- 1 min
- Arrived on time 96% of the time (55 flights, Jun 2025 to May 2026).
- Never cancelled in 55 scheduled flights.
- Leaves in this route's most on-time window (Before 9 AM: 96% on time; 3 to 6 PM: 65%).
- Short track record (55 flights), so its score leans on the airline's record at this hour.
Limited track record · 55 flights
Find Southwest 4440 fares Opens this date on Aviasales#2 · Southwest 4131
6:15 AM → 9:15 AM2h 00m nonstop
Local times, typical schedule. Last flown 2026-04-05.
91%
chance on time
- On time (history)
- 100%
- Cancelled
- 0.0%
- Avg arrival delay
- 0 min
- Arrived on time 100% of the time (13 flights, Jun 2025 to May 2026).
- Leaves in this route's most on-time window (Before 9 AM: 96% on time; 3 to 6 PM: 65%).
- Short track record (13 flights), so its score leans on the airline's record at this hour.
Limited track record · 13 flights
Find Southwest 4131 fares Opens this date on Aviasales#3 · Southwest 2741
5:20 AM → 8:20 AM2h 00m nonstop
Local times, typical schedule. Last flown 2026-04-06.
89%
chance on time
- On time (history)
- 88%
- Cancelled
- 0.0%
- Avg arrival delay
- 5 min
- Arrived on time 88% of the time (25 flights, Jun 2025 to May 2026).
- Leaves in this route's most on-time window (Before 9 AM: 96% on time; 3 to 6 PM: 65%).
- Short track record (25 flights), so its score leans on the airline's record at this hour.
Limited track record · 25 flights
Find Southwest 2741 fares Opens this date on Aviasales#4 · Southwest 2098
11:15 AM → 2:15 PM2h 00m nonstop
Local times, typical schedule. Last flown 2026-05-29.
88%
chance on time
- On time (history)
- 96%
- Cancelled
- 0.0%
- Avg arrival delay
- 4 min
- Arrived on time 96% of the time (23 flights, Jun 2025 to May 2026).
- Lands inside BWI's trouble window: 81% of its 43 ground stops and delay programs started between 2 PM and 8 PM.
- Short track record (23 flights), so its score leans on the airline's record at this hour.
Limited track record · 23 flights
Find Southwest 2098 fares Opens this date on Aviasales#5 · Southwest 2737
1:15 PM → 4:20 PM2h 05m nonstop
Local times, typical schedule. Last flown 2026-05-30.
87%
chance on time
- On time (history)
- 100%
- Cancelled
- 0.0%
- Avg arrival delay
- 0 min
- Arrived on time 100% of the time (24 flights, Jun 2025 to May 2026).
- Lands inside BWI's trouble window: 81% of its 43 ground stops and delay programs started between 2 PM and 8 PM.
- Short track record (24 flights), so its score leans on the airline's record at this hour.
Limited track record · 24 flights
Find Southwest 2737 fares Opens this date on Aviasales#6 · Southwest 2390
1:40 PM → 4:40 PM2h 00m nonstop
Local times, typical schedule. Last flown 2026-04-06.
82%
chance on time
- On time (history)
- 86%
- Cancelled
- 6.7%
- Avg arrival delay
- 5 min
- Arrived on time 86% of the time (14 flights, Jun 2025 to May 2026).
- Lands inside BWI's trouble window: 81% of its 43 ground stops and delay programs started between 2 PM and 8 PM.
- Short track record (14 flights), so its score leans on the airline's record at this hour.
Limited track record · 14 flights
Find Southwest 2390 fares Opens this date on Aviasales#7 · Southwest 2523
4:45 PM → 7:40 PM1h 55m nonstop
Local times, typical schedule. Last flown 2026-04-06.
75%
chance on time
- On time (history)
- 73%
- Cancelled
- 3.6%
- Avg arrival delay
- 20 min
- Arrived on time 73% of the time (26 flights, Jun 2025 to May 2026).
- Leaves in this route's least on-time window (3 to 6 PM: 65% on time; Before 9 AM: 96%).
- Lands inside BWI's trouble window: 81% of its 43 ground stops and delay programs started between 2 PM and 8 PM.
- Short track record (26 flights), so its score leans on the airline's record at this hour.
Limited track record · 26 flights
Find Southwest 2523 fares Opens this date on Aviasales#8 · Southwest 3144
4:00 PM → 7:05 PM2h 05m nonstop
Local times, typical schedule. Last flown 2026-05-29.
73%
chance on time
- On time (history)
- 74%
- Cancelled
- 0.0%
- Avg arrival delay
- 13 min
- Arrived on time 74% of the time (23 flights, Jun 2025 to May 2026).
- Leaves in this route's least on-time window (3 to 6 PM: 65% on time; Before 9 AM: 96%).
- Lands inside BWI's trouble window: 81% of its 43 ground stops and delay programs started between 2 PM and 8 PM.
- 75% of its delay minutes came from the plane arriving late from an earlier flight.
Limited track record · 23 flights
Find Southwest 3144 fares Opens this date on Aviasales#9 · Southwest 4442
7:45 PM → 10:45 PM2h 00m nonstop
Local times, typical schedule. Last flown 2026-05-31. Same departure also flew as Southwest 4633; its record covers all of them.
68%
chance on time
- On time (history)
- 67%
- Cancelled
- 0.0%
- Avg arrival delay
- 27 min
- Arrived on time 67% of the time (88 flights, Jun 2025 to May 2026).
- Never cancelled in 88 scheduled flights.
- 58% of its delay minutes came from the plane arriving late from an earlier flight.
Moderate track record · 88 flights
Find Southwest 4442 fares Opens this date on Aviasales
Airlines on this route
Season-adjusted chance of operating and arriving on time.
- Southwest Airlines80%
1,288 flights · 81% on time as flown · 1.2% cancel
On time by departure time
All airlines, scheduled local departure, Jun 2025 to May 2026.
- Before 9 AM96%
427 flights · avg delay 3 min
- 9 AM to noon92%
189 flights · avg delay 7 min
- Noon to 3 PM79%
172 flights · avg delay 13 min
- 3 to 6 PM65%
194 flights · avg delay 22 min
- 6 to 9 PM66%
292 flights · avg delay 24 min
Best day: Tuesday (86%). Worst: Sunday (79%).
Historical odds, not a guarantee. Built from the US DOT Bureau of Transportation Statistics on-time reports (Jun 2025 to May 2026), FAA ground stop and delay program advisories, and 20 years of airport weather observations. Covers US airlines that report to the DOT; schedules are flights operated recently, so confirm times when you book. ATIS Alerts is not affiliated with any airline. Fares are what Aviasales travelers saw in recent searches (USD, one way, 1 adult), not live quotes; the partner site shows the current price. Fare links go to our travel partner and may earn us a commission at no cost to you. Affiliate disclosure