Boeing 737 and Airbus A320 accident near Sfo International Airport, California, August 6, 2019
On August 6, 2019 at about 6:00 am local time, 2 aircraft, Boeing 737 (N37437) and Airbus A320 (N432UA), were involved in the same accident near Sfo International Airport, California (San Francisco Intl airport). No one was hurt; 305 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
the ramp controller directing a Boeing 737 to hold in a location that was marked for a regional jet.
the ramp controller directing a Boeing 737 to hold in a location that was marked for a regional jet.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 6, 2019 · about 6:00 am local time
- Place
- Sfo International Airport, California · San Francisco Intl · map
- Type
- Accident · collision on the ground
- Injuries
- No one was hurt; 305 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft 1
- Boeing 737 924ER, built 2009 · all 737s on the register
- Registration
- N37437 · registry record · serial 33532
- Damage
- Minor damage
- Flight
- Flight · scheduled airline rules (Part 121)
- Aircraft 2
- Airbus A320 232, built 1996 · all A320s on the register
- Registration
- N432UA · registry record · serial 587
- Damage
- Substantial damage
- Flight
- Flight · scheduled airline rules (Part 121)
The NTSB's narrative for the Boeing 737 final · quoted from the NTSB record
On August 5, 2019, at about 2315 PDT, United (UA) flight 435, a Boeing B737-924ER, N37437, collided with UA flight 2201, an Airbus A320-232, N432UA, while taxiing to the gate after landing at San Francisco International Airport (SFO), San Francisco, California. There were no injuries to the passengers or crew on either airplane. The B737 sustained minor damage and the A320 sustained substantial damage. Both flights were operating as 14 Code of Federal Regulations Part 121 scheduled passenger flights. Flight 435 had arrived from Ellison Onizuka Kona International Airport at Keahole (KOA), Kailua-Kona, Hawaii, and flight 2201 arrived from Los Angeles International Airport (LAX), Los Angeles, California. The captain of UA 435 stated that after landing, they were instructed by United G Ramp Tower (Ramp Tower) to hold at Plot 9, spot 11-1 to await a gate. When they arrived at the spot, UA 2201 was parked at spot 11-2 and another Airbus A320 was parked at spot 11-3. When UA 435 was cleared to taxi from spot 11-1, the captain noted that they were centered on their taxi line (11-1) and that UA flight 2201 was centered on their line (11-2). The captain ensured his left wingtip was clear of UA 2201 as he began to taxi and then turned his attention back forward to continue the taxi. A few seconds later, he felt a moderate bump and the nose pulled to the left. The captain stopped the airplane and set the parking brake and observed that their left winglet had struck UA 2201's right wing. The Federal Aviation Administration (FAA) Principal Avionics Inspector (PAI) for United stated the distance between Spot 11-1 and Spot 11-2 was 100 feet. SFO airport operations marked the nose landing gear tire locations of both aircraft after the event and found that UA 2201 was parked 4 feet off the centerline, closer to spot 11-3, resulting in an effective distance between spot 11-1 and 11-2 of 104 feet. The wingspan of UA 2201's A320 was 117 feet and UA 435's B737 was 117 feet, so the provided spacing should have been over 117 feet to keep the wingtips from touching. The spacing between the centerlines for spot 11-1 and 11-2 was inadequate for UA flight 435 to have cleared the wing of UA 2201. Examination of the pilot charts and Ramp Tower maps found differences for parking spots 11-1 through 11-3. The pilot chart depicted taxi lines that existed prior to restriping that occurred in March 2015. The old taxi lines, before restriping, had the centerlines of spot 11-1 and 11-2 further away from each other and would have given sufficient spacing for a B737 and an A320. The Ramp Tower's Procedures Manual identified the largest airplane allowed for parking Spot 11-1 was a "CRJ", which has a wingspan of about 76 feet. For Spots 11-2 and 11-3 the largest airplane indicated is a Boeing B757-300W. However, United Ramp Tower directed UA flight 435, a Boeing 737, to park on Spot 11-1. Subsequent to the accident, the operator published a revised chart and sent an alert to pilots of the changes.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The NTSB's narrative for the Airbus A320 final · quoted from the NTSB record
On August 5, 2019, at about 2315 PDT, United (UA) flight 435, a Boeing B737-924ER, N37437, collided with UA flight 2201, an Airbus A320-232, N432UA, while taxiing to the gate after landing at San Francisco International Airport (SFO), San Francisco, California. There were no injuries to the passengers or crew on either airplane. The B737 sustained minor damage and the A320 sustained substantial damage. Both flights were operating as 14 Code of Federal Regulations Part 121 scheduled passenger flights. Flight 435 had arrived from Ellison Onizuka Kona International Airport at Keahole (KOA), Kailua-Kona, Hawaii, and flight 2201 arrived from Los Angeles International Airport (LAX), Los Angeles, California. The captain of UA 435 stated that after landing, they were instructed by United G Ramp Tower (Ramp Tower) to hold at Plot 9, spot 11-1 to await a gate. When they arrived at the spot, UA 2201 was parked at spot 11-2 and another Airbus A320 was parked at spot 11-3. When UA 435 was cleared to taxi from spot 11-1, the captain noted that they were centered on their taxi line (11-1) and that UA flight 2201 was centered on their line (11-2). The captain ensured his left wingtip was clear of UA 2201 as he began to taxi and then turned his attention back forward to continue the taxi. A few seconds later, he felt a moderate bump and the nose pulled to the left. The captain stopped the airplane and set the parking brake and observed that their left winglet had struck UA 2201's right wing. The Federal Aviation Administration (FAA) Principal Avionics Inspector (PAI) for United stated the distance between Spot 11-1 and Spot 11-2 was 100 feet. SFO airport operations marked the nose landing gear tire locations of both aircraft after the event and found that UA 2201 was parked 4 feet off the centerline, closer to spot 11-3, resulting in an effective distance between spot 11-1 and 11-2 of 104 feet. The wingspan of UA 2201's A320 was 117 feet and UA 435's B737 was 117 feet, so the provided spacing should have been over 117 feet to keep the wingtips from touching. The spacing between the centerlines for spot 11-1 and 11-2 was inadequate for UA flight 435 to have cleared the wing of UA 2201. Examination of the pilot charts and Ramp Tower maps found differences for parking spots 11-1 through 11-3. The pilot chart depicted taxi lines that existed prior to restriping that occurred in March 2015. The old taxi lines, before restriping, had the centerlines of spot 11-1 and 11-2 further away from each other and would have given sufficient spacing for a B737 and an A320. The Ramp Tower's Procedures Manual identified the largest airplane allowed for parking Spot 11-1 was a "CRJ", which has a wingspan of about 76 feet. For Spots 11-2 and 11-3 the largest airplane indicated is a Boeing B757-300W. However, United Ramp Tower directed UA flight 435, a Boeing 737, to park on Spot 11-1. Subsequent to the accident, the operator published a revised chart and sent an alert to pilots of the changes.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record for the Boeing 737 from the NTSB's investigation tables, in plain English
What happened, in order
- Airport occurrence during taxi defining event
The NTSB's findings
- cause Organizational issues › Support/oversight/monitoring › Documentation/record keeping › (general) › Operator
- Personnel issues › Task performance › Communication (personnel) › Issuing instructions › Ground crew
Pilot
- Certificate: airline transport pilot, flight engineer
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 19,500 hours in all; 7,255 in this make and model; 180 in the last 90 days; 90 in the last 30 days; 9,860 as pilot in command; 350 on instruments
- Last flight review: May 3, 2019
- Medical certificate: Class 1 (with waivers/limitations)
- Seat: left
- Injury: no injuries
Co-pilot
- Certificate: airline transport pilot, commercial pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 6,415 hours in all; 1,836 in this make and model; 134 in the last 90 days; 37 in the last 30 days; 1,590 as pilot in command
- Last flight review: January 13, 2019
- Medical certificate: Class 1 (without waivers/limitations)
- Seat: rgt
- Injury: no injuries
The aircraft
- Landing gear: retractable
- Engine 1: Cfm Intl CFM56-7B26/3; 0 hours total
- Engine 2: Cfm Intl CFM56-7B26/3; 0 hours total
- Operator: United Air Lines INC
The flight
- Departed from: KOA Kailua/Kona HI
- Destination: SFO Sfo International Airport CA
- A second pilot was aboard
Weather at the time
- Light: night
- Sky: not recorded; not recorded
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Cabi | 4 | |||
| Flight crew | 2 | |||
| Passengers | 157 |
The factual record for the Airbus A320 from the NTSB's investigation tables, in plain English
What happened, in order
- Airport occurrence during standing defining event
The NTSB's findings
- cause Organizational issues › Support/oversight/monitoring › Documentation/record keeping › (general) › Operator
- Personnel issues › Task performance › Communication (personnel) › Issuing instructions › Ground crew
The aircraft
- Maximum gross weight: 169,756 lb
- Landing gear: retractable
- Engine 1: Iae V2500SERIES (turbofan); 0 hours total
- Engine 2: Iae V2500SERIES (turbofan); 0 hours total
- Operator: United Air Lines INC
The flight
- Departed from: LAX Los Angeles CA
- Destination: SFO Sfo International Airport CA
- A second pilot was aboard
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Cabi | 3 | |||
| Flight crew | 2 | |||
| Passengers | 137 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The NTSB has not released the docket for this case yet. The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), is usually released when the investigation is nearly complete, and the list here is refreshed when it appears. Check at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.