Flight UA1639
United Airlines flight UA1639
Looking for UA1639 in the airâŚ
Alerts at this flight's airports
Denver (DEN) to St Louis (STL)
Historically, this flight arrives 15+ minutes late 18% of the time, and when it is late the delay averages 103 minutes. It was cancelled 0.0% of the time.
- On-time arrivals
- 82.4%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 103 min
- Flights arriving 15+ minutes late
- Flights tracked
- 102
- Scheduled flights in the period
What caused the delays
- Airline (crew, maintenance, cleaning) 40%
- Late-arriving aircraft 39%
- Air traffic control & airport 20%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
St Louis (STL) to Chicago (ORD)
Historically, this flight arrives 15+ minutes late 36% of the time, and when it is late the delay averages 123 minutes. It was cancelled 4.9% of the time.
- On-time arrivals
- 64.1%
- Less than 15 minutes late
- Cancelled
- 4.9%
- Of scheduled flights
- Average delay when late
- 123 min
- Flights arriving 15+ minutes late
- Flights tracked
- 82
- Scheduled flights in the period
What caused the delays
- Air traffic control & airport 47%
- Airline (crew, maintenance, cleaning) 39%
- Late-arriving aircraft 14%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
San Francisco (SFO) to Redmond (RDM)
Historically, this flight arrives 15+ minutes late 11% of the time, and when it is late the delay averages 39 minutes. It was cancelled 0.0% of the time.
- On-time arrivals
- 89.1%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 39 min
- Flights arriving 15+ minutes late
- Flights tracked
- 55
- Scheduled flights in the period
What caused the delays
- Air traffic control & airport 70%
- Airline (crew, maintenance, cleaning) 21%
- Late-arriving aircraft 9%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Miami (MIA) to Chicago (ORD)
Historically, this flight arrives 15+ minutes late 57% of the time, and when it is late the delay averages 62 minutes. It was cancelled 3.8% of the time.
- On-time arrivals
- 43.1%
- Less than 15 minutes late
- Cancelled
- 3.8%
- Of scheduled flights
- Average delay when late
- 62 min
- Flights arriving 15+ minutes late
- Flights tracked
- 53
- Scheduled flights in the period
What caused the delays
- Air traffic control & airport 51%
- Late-arriving aircraft 40%
- Airline (crew, maintenance, cleaning) 10%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
San Luis Obispo (SBP) to San Francisco (SFO)
Historically, this flight arrives 15+ minutes late 23% of the time, and when it is late the delay averages 125 minutes. It was cancelled 0.0% of the time.
- On-time arrivals
- 77.4%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 125 min
- Flights arriving 15+ minutes late
- Flights tracked
- 53
- Scheduled flights in the period
What caused the delays
- Airline (crew, maintenance, cleaning) 92%
- Air traffic control & airport 8%
- Late-arriving aircraft 0%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
San Francisco (SFO) to New Orleans (MSY)
Historically, this flight arrives 15+ minutes late 9% of the time, and when it is late the delay averages 33 minutes. It was cancelled 0.0% of the time.
- On-time arrivals
- 91.4%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 33 min
- Flights arriving 15+ minutes late
- Flights tracked
- 35
- Scheduled flights in the period
What caused the delays
- Air traffic control & airport 56%
- Late-arriving aircraft 44%
- Airline (crew, maintenance, cleaning) 0%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
San Francisco (SFO) to Austin (AUS)
Historically, this flight arrives 15+ minutes late 38% of the time, and when it is late the delay averages 54 minutes. It was cancelled 0.0% of the time.
- On-time arrivals
- 61.9%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 54 min
- Flights arriving 15+ minutes late
- Flights tracked
- 21
- Scheduled flights in the period
What caused the delays
- Air traffic control & airport 46%
- Airline (crew, maintenance, cleaning) 35%
- Late-arriving aircraft 19%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Fort Myers (RSW) to Chicago (ORD)
Only 17 flights on record, which is too few for reliable odds.
- On-time arrivals
- 82.4%
- Less than 15 minutes late
- Cancelled
- 0.0%
- Of scheduled flights
- Average delay when late
- 47 min
- Flights arriving 15+ minutes late
- Flights tracked
- 17
- Scheduled flights in the period
What caused the delays
- Late-arriving aircraft 65%
- Air traffic control & airport 35%
- Airline (crew, maintenance, cleaning) 0%
- Extreme weather 0%
- Security 0%
Share of delay minutes airlines attributed to each cause (BTS).
Chicago (ORD) to Dulles (IAD)
Only 6 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
- 47 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).
Houston (IAH) to Nashville (BNA)
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
- â
- 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 | 86.7% | 30 |
| October 2025 | 93.5% | 31 |
| November 2025 | 89.7% | 29 |
| December 2025 | 74.1% | 27 |
| January 2026 | 75.0% | 16 |
| February 2026 | 28.6% | 14 |
| March 2026 | 33.3% | 23 |
| April 2026 | 87.1% | 31 |
| May 2026 | 69.4% | 62 |
| June 2026 | 81.4% | 60 |
| July 2026 | 69.0% | 61 |
| August 2026 | 68.3% | 41 |
Source: U.S. DOT Bureau of Transportation Statistics on-time data, September 2025 â August 2026. Covers flights operated by reporting U.S. carriers. About our data