Route on-time record
STL to PHL: most on-time flights and the best time to fly
St Louis (St. Louis Lambert International Airport) to Philadelphia (Philadelphia International Airport). 1,572 nonstop flights in Jun 2025 to May 2026, 79% arrived within 15 minutes and 1.5% were cancelled. The most reliable flight number was American 1308 at 6:29 AM.
Flying on a specific date? We’ll adjust for the month, the weekday and the forecast.
STL → PHL
St Louis to Philadelphia: 1,572 nonstop flights a year
On time (12 months)
79%
Cancelled
1.5%
avg delay 19 min
Best time to leave
Before 9 AM
91% on time vs 59% 3 to 6 PM
Most reliable airline
American
79% chance on time
Lowest nonstop fare seen in the next two months: $138 (American 4604 on 2026-11-14). 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 · American 1308
6:29 AM → 9:45 AM2h 16m nonstop
Local times, typical schedule. Last flown 2026-05-31.
87%
chance on time
- On time (history)
- 87%
- Cancelled
- 0.7%
- Avg arrival delay
- 10 min
- Arrived on time 87% of the time (152 flights, Jun 2025 to May 2026).
- Leaves in this route's most on-time window (Before 9 AM: 91% on time; 3 to 6 PM: 59%).
Moderate track record · 152 flights
Find American 1308 fares Opens this date on Aviasales#2 · American 2720
11:18 AM → 2:39 PM2h 21m nonstop
Local times, typical schedule. Last flown 2026-05-31.
85%
chance on time
- On time (history)
- 100%
- Cancelled
- 0.0%
- Avg arrival delay
- 0 min
- Arrived on time 100% of the time (9 flights, Jun 2025 to May 2026).
- Lands inside PHL's trouble window: 72% of its 95 ground stops and delay programs started between 2 PM and 8 PM.
Limited track record · 9 flights
Find American 2720 fares Opens this date on Aviasales#3 · American 3130
1:29 PM → 4:49 PM2h 20m nonstop
Local times, typical schedule. Last flown 2026-05-20.
84%
chance on time
- On time (history)
- 89%
- Cancelled
- 0.0%
- Avg arrival delay
- 12 min
- Arrived on time 89% of the time (38 flights, Jun 2025 to May 2026).
- Never cancelled in 38 scheduled flights.
- Lands inside PHL's trouble window: 72% of its 95 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 · 38 flights
Find American 3130 fares Opens this date on Aviasales#4 · Southwest 4504
10:15 AM → 1:25 PM2h 10m nonstop
Local times, typical schedule. Last flown 2026-05-31.
80%
chance on time
- On time (history)
- 80%
- Cancelled
- 0.0%
- Avg arrival delay
- 23 min
- Arrived on time 80% of the time (30 flights, Jun 2025 to May 2026).
- Never cancelled in 30 scheduled flights.
- 71% of its delay minutes came from the plane arriving late from an earlier flight.
Limited track record · 30 flights
Find Southwest 4504 fares Opens this date on Aviasales#5 · Southwest 3727
1:35 PM → 4:45 PM2h 10m nonstop
Local times, typical schedule. Last flown 2026-05-29.
75%
chance on time
- On time (history)
- 72%
- Cancelled
- 0.0%
- Avg arrival delay
- 18 min
- Arrived on time 72% of the time (39 flights, Jun 2025 to May 2026).
- Never cancelled in 39 scheduled flights.
- Lands inside PHL's trouble window: 72% of its 95 ground stops and delay programs started between 2 PM and 8 PM.
- 67% of its delay minutes came from the plane arriving late from an earlier flight.
Limited track record · 39 flights
Find Southwest 3727 fares Opens this date on Aviasales#6 · American 2714
5:40 PM → 9:09 PM2h 29m nonstop
Local times, typical schedule. Last flown 2026-05-31.
71%
chance on time
- On time (history)
- 60%
- Cancelled
- 0.0%
- Avg arrival delay
- 14 min
- Arrived on time 60% of the time (10 flights, Jun 2025 to May 2026).
- Leaves in this route's least on-time window (3 to 6 PM: 59% on time; Before 9 AM: 91%).
- 66% of its delay minutes came from the plane arriving late from an earlier flight.
Limited track record · 10 flights
Find American 2714 fares Opens this date on Aviasales#7 · Southwest 3022
7:55 PM → 11:05 PM2h 10m nonstop
Local times, typical schedule. Last flown 2026-05-31.
70%
chance on time
- On time (history)
- 70%
- Cancelled
- 0.0%
- Avg arrival delay
- 20 min
- Arrived on time 70% of the time (54 flights, Jun 2025 to May 2026).
- Never cancelled in 55 scheduled flights.
- 57% of its delay minutes came from the plane arriving late from an earlier flight.
Limited track record · 54 flights
Find Southwest 3022 fares Opens this date on Aviasales
Airlines on this route
Season-adjusted chance of operating and arriving on time.
- American Airlines79%
615 flights · 80% on time as flown · 1.3% cancel
- Southwest Airlines77%
723 flights · 77% on time as flown · 0.7% cancel
On time by departure time
All airlines, scheduled local departure, Jun 2025 to May 2026.
- Before 9 AM91%
566 flights · avg delay 12 min
- 9 AM to noon85%
173 flights · avg delay 18 min
- Noon to 3 PM79%
376 flights · avg delay 17 min
- 3 to 6 PM59%
196 flights · avg delay 39 min
- 6 to 9 PM66%
239 flights · avg delay 21 min
Best day: Wednesday (83%). Worst: Friday (77%).
On time by month
All airlines, Jun 2023 to May 2026. Several years per month, so one stormy season doesn't define a month. Travel-month estimates use this seasonal pattern.
What delays this route
- Late-arriving aircraft50%
- Airline (crew, maintenance, boarding)38%
- Air traffic control and airport volume9%
- Severe weather3%
Share of delay minutes by the cause airlines report to the US DOT.
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
STL to PHL questions
- What time of day is best to fly STL to PHL?
- Before 9 AM: 91% of flights arrived on time, against 59% for departures 3 to 6 PM. Later flights inherit delays from earlier ones, so the first departures of the day usually run best.
- Which airline is most on time from STL to PHL?
- American, with a season-adjusted 79% chance of operating and arriving on time over 615 flights. The adjustment compares each airline with what the route did in the months it flew, so a carrier that skipped a stormy month gets no free credit.
- What is the worst month for delays on STL to PHL?
- July (69% on time); the best was February (87%), averaged over Jun 2023 to May 2026.
- Is this a prediction for my flight?
- No. These are historical odds from the US DOT on-time reports, FAA advisories and airport weather records. Check your flight status and the FAA delay board on the day you fly.
More routes from STL
- PHL to STL (return)
- STL to ATL 85%
- STL to DEN 75%
- STL to ORD 71%
- STL to LGA 75%
- STL to MCO 78%
- STL to DCA 73%
- STL to DFW 74%
- STL to PHX 76%
- STL to LAS 79%
- STL to DAL 77%
- STL to DTW 83%
- STL to MSP 80%
Most on-time flights from STL on every route →
Live status: FAA delays and ground stops