# NTSB DCA19CA192: Boeing 737, N37437, SFO International Airport, CA, August 6, 2019 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 4 · Data collection · Final report - Date: August 5, 2019, 23:00 local (Aug 6, 2019, 06:00 UTC) - Place: SFO International Airport, CA - Coordinates: 37.615276, -122.389999 - Nearby events: https://openairdocs.org/map.md?lat=37.6153&lon=-122.3900&mi=10 - Phase of flight: [Taxi](https://openairdocs.org/ntsb-phases/250) (OpenAirDocs' grouping) - Defining events: [Taxi: Airport occurrence](https://openairdocs.org/ntsb-events/070); [Standing: Airport occurrence](https://openairdocs.org/ntsb-events/070) - Highest injury: No injuries - Injuries: 305 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 4 - Basic report with no Prelim publish - NTSB office: Major Investigations Division - NTSB case key (mKey): 100018 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DCA19CA192 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/100018/pdf - Page: https://openairdocs.org/ntsb/DCA19CA192 ## Probable cause (aircraft 1) the ramp controller directing a Boeing 737 to hold in a location that was marked for a regional jet. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Documentation/record keeping](https://openairdocs.org/ntsb-findings/04033000): Organizational issues › Support/oversight/monitoring · Operator (probable cause), aircraft 1; cases with it: [Boeing 737-924ER, 1 case](https://openairdocs.org/ntsb-findings/04033000/cases.md?model=13848A3), [All aircraft, 12 cases](https://openairdocs.org/ntsb-findings/04033000/cases.md) - [Communication (personnel): issuing instructions](https://openairdocs.org/ntsb-findings/02063538): Personnel issues › Task performance · Ground crew (probable cause), aircraft 1; cases with it: [Boeing 737-924ER, 1 case](https://openairdocs.org/ntsb-findings/02063538/cases.md?model=13848A3), [All aircraft, 26 cases](https://openairdocs.org/ntsb-findings/02063538/cases.md) - [Documentation/record keeping](https://openairdocs.org/ntsb-findings/04033000): Organizational issues › Support/oversight/monitoring · Operator (probable cause), aircraft 2; cases with it: [Airbus Industrie A320-232, 1 case](https://openairdocs.org/ntsb-findings/04033000/cases.md?model=3930326), [All aircraft, 12 cases](https://openairdocs.org/ntsb-findings/04033000/cases.md) - [Communication (personnel): issuing instructions](https://openairdocs.org/ntsb-findings/02063538): Personnel issues › Task performance · Ground crew (probable cause), aircraft 2; cases with it: [Airbus Industrie A320-232, 1 case](https://openairdocs.org/ntsb-findings/02063538/cases.md?model=3930326), [All aircraft, 26 cases](https://openairdocs.org/ntsb-findings/02063538/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Taxi: Airport occurrence](https://openairdocs.org/ntsb-events/070) (defining event), aircraft 1; cases with it: [Boeing 737-924ER, 1 case](https://openairdocs.org/ntsb-events/070/sequence.md?model=13848A3), [All aircraft, 57 cases](https://openairdocs.org/ntsb-events/070/sequence.md) - [Standing: Airport occurrence](https://openairdocs.org/ntsb-events/070) (defining event), aircraft 2; cases with it: [Airbus Industrie A320-232, 1 case](https://openairdocs.org/ntsb-events/070/sequence.md?model=3930326), [All aircraft, 57 cases](https://openairdocs.org/ntsb-events/070/sequence.md) ## Analysis (aircraft 1) 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 ofthe changes. ## Aircraft 1 - Registration: [N37437](https://openairdocs.org/aircraft/N37437), registered now, S/N 33532, built 2009 (OpenAirDocs) - Reported make and model: Boeing 737 (924ER) - Registry model: [Boeing 737-924ER](https://openairdocs.org/model/boeing-737-924er) (registry code 13848A3) (OpenAirDocs) - Registry engine: [CFM International CFM56-7B26/3 series](https://openairdocs.org/engine/cfm-international-cfm56-7b26-3-series) (registry code 13073, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 33532 - Year built: 2009 - Engines: Cfm Intl CFM56-7B26/3; Cfm Intl CFM56-7B26/3 - Damage: Minor damage - Flight: Part 121 - Operator: United Air Lines Inc - Registered owner: United Airlines Inc - Airworthiness certificate: Standard, Transport - Departed: KOA, Kailua/Kona, HI - Destination: SFO, SFO International Airport, CA - Airport: SFO, San Francisco Intl ## Aircraft 2 - Registration: [N432UA](https://openairdocs.org/aircraft/N432UA), registered now, S/N 587, built 1996 (OpenAirDocs) - Reported make and model: Airbus A320 (232) - Registry model: [Airbus Industrie A320-232](https://openairdocs.org/model/airbus-industrie-a320-232) (registry code 3930326) (OpenAirDocs) - Registry engine: [IAE V2500SERIES](https://openairdocs.org/engine/iae-v2500series) (registry code 34601, turbo-jet) (OpenAirDocs) - Category: Airplane - Serial number: 587 - Year built: 1996 - Engines: Iae V2500SERIES 9895 horsepower turbo fan; Iae V2500SERIES 9895 horsepower turbo fan - Damage: Substantial damage - Flight: Part 121 - Operator: United Air Lines Inc - Registered owner: Us Bank Na Trustee - Airworthiness certificate: Standard, Transport - Departed: LAX, Los Angeles, CA - Destination: SFO, SFO International Airport, CA - Airport: SFO, San Francisco Intl ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot, aircraft N37437; age 57; injuries: none; airline transport, flight engineer; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review May 3, 2019; seat: left; flight hours: 19,500 total, 7,255 in this make and model, 9,860 as pilot in command, 180 in the last 90 days, 90 in the last 30 days, 5 in the last 24 hours - Co-pilot, aircraft N37437; age 40; injuries: none; commercial, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review January 13, 2019; seat: right; flight hours: 6,415 total, 1,836 in this make and model, 1,590 as pilot in command, 134 in the last 90 days, 37 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Night ## FAA reports on this event (2) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 20190805017641I](https://openairdocs.org/incident/20190805017641I), Aug 5, 2019: Boeing 737-924ER, San Francisco, CA, Minor damage. United flight ual 435 arrived at sfo uneventfully. After departing movement area, united boarding area g ramp tower directed UAL435 to park in spot 11-1 at… - [Accident 20190805017631A](https://openairdocs.org/incident/20190805017631A), Aug 5, 2019: Airbus Industrie A320-232, San Francisco, CA, Substantial damage. United flight UAL2201 arrived at sfo uneventfully. After departing movement area, united boarding area g ramp tower directed UAL2201 to hold at spot 11-2 at… From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.