Flight UA520
United Airlines flight UA520
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Alerts at this flight's airports
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Watch Ground Delay Program SAN
Ground Delay Program at San Diego International Airport (SAN): Average 37 minutes, up to 1 hour and 11 minutes
Reason: airport volume
Airport status
-
Advisory Airport Closure SNA
Airport Closure at John Wayne Orange County International Airport (SNA): Reopens Nov 08 at 14:15 UTC.
Airport status
San Francisco (SFO) to Orlando (MCO)
Historically, this flight arrives 15+ minutes late 24% of the time, and when it is late the delay averages 58 minutes. It was cancelled 0.0% of the time.
- On-time arrivals
- 76.1%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 58 min
- Flights arriving 15+ minutes late
- Flights tracked
- 138
- Scheduled flights in the period
What caused the delays
- Late-arriving aircraft 68%
- Air traffic control & airport 20%
- Airline (crew, maintenance, cleaning) 11%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Los Angeles (LAX) to San Francisco (SFO)
Historically, this flight arrives 15+ minutes late 33% of the time, and when it is late the delay averages 51 minutes. It was cancelled 0.0% of the time.
- On-time arrivals
- 66.7%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 51 min
- Flights arriving 15+ minutes late
- Flights tracked
- 99
- Scheduled flights in the period
What caused the delays
- Air traffic control & airport 62%
- Airline (crew, maintenance, cleaning) 19%
- Late-arriving aircraft 19%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Phoenix (PHX) to Chicago (ORD)
Historically, this flight arrives 15+ minutes late 23% of the time, and when it is late the delay averages 69 minutes. It was cancelled 0.0% of the time.
- On-time arrivals
- 76.6%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 69 min
- Flights arriving 15+ minutes late
- Flights tracked
- 77
- Scheduled flights in the period
What caused the delays
- Air traffic control & airport 54%
- Late-arriving aircraft 32%
- Airline (crew, maintenance, cleaning) 13%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
San Francisco (SFO) to Phoenix (PHX)
Historically, this flight arrives 15+ minutes late 11% of the time, and when it is late the delay averages 56 minutes. It was cancelled 0.0% of the time.
- On-time arrivals
- 89.2%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 56 min
- Flights arriving 15+ minutes late
- Flights tracked
- 37
- Scheduled flights in the period
What caused the delays
- Airline (crew, maintenance, cleaning) 73%
- Air traffic control & airport 27%
- Late-arriving aircraft 0%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
San Francisco (SFO) to Philadelphia (PHL)
Historically, this flight arrives 15+ minutes late 17% of the time, and when it is late the delay averages 59 minutes. It was cancelled 0.0% of the time.
- On-time arrivals
- 83.3%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 59 min
- Flights arriving 15+ minutes late
- Flights tracked
- 36
- Scheduled flights in the period
What caused the delays
- Late-arriving aircraft 61%
- Airline (crew, maintenance, cleaning) 28%
- Air traffic control & airport 11%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
San Diego (SAN) to San Francisco (SFO)
Historically, this flight arrives 15+ minutes late 50% of the time, and when it is late the delay averages 57 minutes. It was cancelled 0.0% of the time.
- On-time arrivals
- 50.0%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 57 min
- Flights arriving 15+ minutes late
- Flights tracked
- 30
- Scheduled flights in the period
What caused the delays
- Air traffic control & airport 73%
- Airline (crew, maintenance, cleaning) 25%
- Late-arriving aircraft 3%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Burbank (BUR) to San Francisco (SFO)
Historically, this flight arrives 15+ minutes late 85% of the time, and when it is late the delay averages 59 minutes. It was cancelled 4.8% of the time.
- On-time arrivals
- 15.0%
- Less than 15 minutes late
- Cancelled
- 4.8%
- Of scheduled flights
- Average delay when late
- 59 min
- Flights arriving 15+ minutes late
- Flights tracked
- 21
- Scheduled flights in the period
What caused the delays
- Air traffic control & airport 100%
- Airline (crew, maintenance, cleaning) 0%
- Late-arriving aircraft 0%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
San Francisco (SFO) to Salt Lake City (SLC)
Historically, this flight arrives 15+ minutes late 62% of the time, and when it is late the delay averages 58 minutes. It was cancelled 0.0% of the time.
- On-time arrivals
- 38.1%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 58 min
- Flights arriving 15+ minutes late
- Flights tracked
- 21
- Scheduled flights in the period
What caused the delays
- Air traffic control & airport 37%
- Airline (crew, maintenance, cleaning) 36%
- Late-arriving aircraft 27%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Miami (MIA) to Chicago (ORD)
Only 18 flights on record, which is too few for reliable odds.
- On-time arrivals
- 94.4%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 40 min
- Flights arriving 15+ minutes late
- Flights tracked
- 18
- Scheduled flights in the period
What caused the delays
- Air traffic control & airport 100%
- Airline (crew, maintenance, cleaning) 0%
- Late-arriving aircraft 0%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Salt Lake City (SLC) to Denver (DEN)
Only 15 flights on record, which is too few for reliable odds.
- On-time arrivals
- 57.1%
- Less than 15 minutes late
- Cancelled
- 6.7%
- Of scheduled flights
- Average delay when late
- 94 min
- Flights arriving 15+ minutes late
- Flights tracked
- 15
- Scheduled flights in the period
What caused the delays
- Air traffic control & airport 58%
- Late-arriving aircraft 41%
- Airline (crew, maintenance, cleaning) 1%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Houston (IAH) to New York (LGA)
Only 6 flights on record, which is too few for reliable odds.
- On-time arrivals
- 40.0%
- Less than 15 minutes late
- Cancelled
- 16.7%
- Of scheduled flights
- Average delay when late
- 40 min
- Flights arriving 15+ minutes late
- Flights tracked
- 6
- Scheduled flights in the period
What caused the delays
- Extreme weather 37%
- Air traffic control & airport 31%
- Late-arriving aircraft 25%
- Airline (crew, maintenance, cleaning) 7%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Jackson (JAC) to Houston (IAH)
Only 6 flights on record, which is too few for reliable odds.
- On-time arrivals
- 83.3%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 121 min
- Flights arriving 15+ minutes late
- Flights tracked
- 6
- Scheduled flights in the period
What caused the delays
- Airline (crew, maintenance, cleaning) 100%
- Late-arriving aircraft 0%
- Air traffic control & airport 0%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Salt Lake City (SLC) to Los Angeles (LAX)
Only 5 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
- 5
- Scheduled flights in the period
Denver (DEN) to Savannah (SAV)
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
Austin (AUS) to Denver (DEN)
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
Chicago (ORD) to Santa Ana (SNA)
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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Show as table
| Month | On time | Flights |
|---|---|---|
| September 2025 | 95.8% | 24 |
| October 2025 | 50.0% | 6 |
| November 2025 | 93.3% | 30 |
| December 2025 | 71.0% | 31 |
| January 2026 | 81.9% | 83 |
| February 2026 | 75.9% | 55 |
| March 2026 | 78.1% | 32 |
| April 2026 | 86.7% | 30 |
| May 2026 | 47.6% | 42 |
| June 2026 | 74.5% | 55 |
| July 2026 | 63.5% | 52 |
| August 2026 | 43.8% | 75 |
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