Flight WN3521
Southwest Airlines flight WN3521
Looking for WN3521 in the air…
Chicago (MDW) to Seattle (SEA)
Historically, this flight arrives 15+ minutes late 19% of the time, and when it is late the delay averages 39 minutes. It was cancelled 0.0% of the time.
- On-time arrivals
- 81.0%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 39 min
- Flights arriving 15+ minutes late
- Flights tracked
- 58
- Scheduled flights in the period
What caused the delays
- Airline (crew, maintenance, cleaning) 58%
- Air traffic control & airport 31%
- Late-arriving aircraft 11%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Kansas City (MCI) to Las Vegas (LAS)
Historically, this flight arrives 15+ minutes late 42% of the time, and when it is late the delay averages 64 minutes. It was cancelled 0.0% of the time.
- On-time arrivals
- 58.3%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 64 min
- Flights arriving 15+ minutes late
- Flights tracked
- 36
- Scheduled flights in the period
What caused the delays
- Late-arriving aircraft 80%
- Air traffic control & airport 9%
- Airline (crew, maintenance, cleaning) 8%
- Extreme weather 3%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Los Angeles (LAX) to San Jose (SJC)
Historically, this flight arrives 15+ minutes late 22% of the time, and when it is late the delay averages 56 minutes. It was cancelled 0.0% of the time.
- On-time arrivals
- 77.8%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 56 min
- Flights arriving 15+ minutes late
- Flights tracked
- 27
- Scheduled flights in the period
What caused the delays
- Late-arriving aircraft 96%
- Airline (crew, maintenance, cleaning) 4%
- Air traffic control & airport 0%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Los Angeles (LAX) to Phoenix (PHX)
Only 16 flights on record, which is too few for reliable odds.
- On-time arrivals
- 100.0%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- —
- Flights arriving 15+ minutes late
- Flights tracked
- 16
- Scheduled flights in the period
Sacramento (SMF) to Los Angeles (LAX)
Only 16 flights on record, which is too few for reliable odds.
- On-time arrivals
- 100.0%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- —
- Flights arriving 15+ minutes late
- Flights tracked
- 16
- Scheduled flights in the period
St Louis (STL) to Panama City Beach (ECP)
Only 12 flights on record, which is too few for reliable odds.
- On-time arrivals
- 66.7%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 59 min
- Flights arriving 15+ minutes late
- Flights tracked
- 12
- Scheduled flights in the period
What caused the delays
- Late-arriving aircraft 59%
- Airline (crew, maintenance, cleaning) 41%
- Air traffic control & airport 0%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Chicago (MDW) to Boston (BOS)
Only 9 flights on record, which is too few for reliable odds.
- On-time arrivals
- 55.6%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 98 min
- Flights arriving 15+ minutes late
- Flights tracked
- 9
- Scheduled flights in the period
What caused the delays
- Air traffic control & airport 53%
- Late-arriving aircraft 43%
- Airline (crew, maintenance, cleaning) 4%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Atlanta (ATL) to Houston (HOU)
Only 8 flights on record, which is too few for reliable odds.
- On-time arrivals
- 75.0%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 115 min
- Flights arriving 15+ minutes late
- Flights tracked
- 8
- Scheduled flights in the period
What caused the delays
- Late-arriving aircraft 91%
- Airline (crew, maintenance, cleaning) 9%
- Air traffic control & airport 0%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Las Vegas (LAS) to Baltimore (BWI)
Only 8 flights on record, which is too few for reliable odds.
- On-time arrivals
- 87.5%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 25 min
- Flights arriving 15+ minutes late
- Flights tracked
- 8
- Scheduled flights in the period
What caused the delays
- Air traffic control & airport 61%
- Airline (crew, maintenance, cleaning) 39%
- Late-arriving aircraft 0%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Sarasota/Bradenton (SRQ) to Orlando (MCO)
Only 8 flights on record, which is too few for reliable odds.
- On-time arrivals
- 37.5%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 111 min
- Flights arriving 15+ minutes late
- Flights tracked
- 8
- Scheduled flights in the period
What caused the delays
- Air traffic control & airport 64%
- Airline (crew, maintenance, cleaning) 36%
- Late-arriving aircraft 1%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Tampa (TPA) to Atlanta (ATL)
Only 8 flights on record, which is too few for reliable odds.
- On-time arrivals
- 75.0%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 110 min
- Flights arriving 15+ minutes late
- Flights tracked
- 8
- Scheduled flights in the period
What caused the delays
- Airline (crew, maintenance, cleaning) 72%
- Air traffic control & airport 15%
- Late-arriving aircraft 13%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Las Vegas (LAS) to Ontario (ONT)
Only 7 flights on record, which is too few for reliable odds.
- On-time arrivals
- 42.9%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 35 min
- Flights arriving 15+ minutes late
- Flights tracked
- 7
- Scheduled flights in the period
What caused the delays
- Late-arriving aircraft 43%
- Airline (crew, maintenance, cleaning) 36%
- Air traffic control & airport 21%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Seattle (SEA) to Las Vegas (LAS)
Only 7 flights on record, which is too few for reliable odds.
- On-time arrivals
- 71.4%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 29 min
- Flights arriving 15+ minutes late
- Flights tracked
- 7
- Scheduled flights in the period
What caused the delays
- Airline (crew, maintenance, cleaning) 51%
- Late-arriving aircraft 24%
- Air traffic control & airport 24%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Las Vegas (LAS) to Los Angeles (LAX)
Only 5 flights on record, which is too few for reliable odds.
- On-time arrivals
- 80.0%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 44 min
- Flights arriving 15+ minutes late
- Flights tracked
- 5
- Scheduled flights in the period
What caused the delays
- Late-arriving aircraft 80%
- Airline (crew, maintenance, cleaning) 20%
- Air traffic control & airport 0%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
PBI → BWI
Only 5 flights on record, which is too few for reliable odds.
- On-time arrivals
- 60.0%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 28 min
- Flights arriving 15+ minutes late
- Flights tracked
- 5
- Scheduled flights in the period
What caused the delays
- Late-arriving aircraft 58%
- Air traffic control & airport 24%
- Airline (crew, maintenance, cleaning) 18%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Dallas (DAL) to Memphis (MEM)
Only 4 flights on record, which is too few for reliable odds.
- On-time arrivals
- 100.0%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- —
- Flights arriving 15+ minutes late
- Flights tracked
- 4
- Scheduled flights in the period
El Paso (ELP) to Los Angeles (LAX)
Only 4 flights on record, which is too few for reliable odds.
- On-time arrivals
- 25.0%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 39 min
- Flights arriving 15+ minutes late
- Flights tracked
- 4
- Scheduled flights in the period
What caused the delays
- Air traffic control & airport 47%
- Late-arriving aircraft 31%
- Airline (crew, maintenance, cleaning) 22%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Houston (HOU) to El Paso (ELP)
Only 4 flights on record, which is too few for reliable odds.
- On-time arrivals
- 75.0%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 32 min
- Flights arriving 15+ minutes late
- Flights tracked
- 4
- Scheduled flights in the period
What caused the delays
- Late-arriving aircraft 86%
- Airline (crew, maintenance, cleaning) 14%
- Air traffic control & airport 0%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Tampa (TPA) to Los Angeles (LAX)
Only 3 flights on record, which is too few for reliable odds.
- On-time arrivals
- 100.0%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- —
- Flights arriving 15+ minutes late
- Flights tracked
- 3
- Scheduled flights in the period
Kansas City (MCI) to Los Angeles (LAX)
Only 1 flight on record, which is too few for reliable odds.
- On-time arrivals
- 100.0%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- —
- Flights arriving 15+ minutes late
- Flights tracked
- 1
- Scheduled flights in the period
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Headlines found by Google News; stories open on the publisher's site.
Show as table
| Month | On time | Flights |
|---|---|---|
| September 2025 | 100.0% | 4 |
| October 2025 | 71.8% | 39 |
| November 2025 | 63.2% | 19 |
| December 2025 | 60.0% | 15 |
| January 2026 | 50.0% | 4 |
| February 2026 | 100.0% | 3 |
| March 2026 | 81.8% | 11 |
| April 2026 | 78.1% | 32 |
| May 2026 | 71.8% | 39 |
| June 2026 | 82.8% | 29 |
| July 2026 | 100.0% | 28 |
| August 2026 | 47.8% | 23 |
Source: U.S. DOT Bureau of Transportation Statistics on-time data, September 2025 – August 2026. Covers flights operated by reporting U.S. carriers. About our data