# NTSB DCA84AA034: Beech C-99, N6399U, San Luis Obispo, CA, August 24, 1984 - Type: NTSB accident investigation - Classification: Accident · Fatal · Class 1 · Final report - Date: August 24, 1984, 11:18 local (18:18 UTC) - Place: San Luis Obispo, CA - Coordinates: 35.278642, -120.66103 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.2786&lon=-120.6610&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Fatal - Injuries: 17 fatal - Status: Completed, report February 6, 1995 - Report: Approved by Office Director - Investigation class: Class 1 - NTSB office: Major Investigations Division - Safety recommendations: Yes - NTSB case key (mKey): 15813 - NTSB case page: https://www.ntsb.gov/investigations/Pages/DCA84AA034.aspx - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/15813/pdf - Board report AAR8507 (PDF): https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR8507.pdf - Page: https://openairdocs.org/ntsb/DCA84AA034 ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Midair collision, climb - to cruise - artcc service - delayed, pilot in command (cause) - insuff standards/requirements,operation/operator, company/operator mgmt (contributing factor) - radar assistance to vfr aircraft - not used, pilot of other aircraft (cause) - radar separation - not possible, atc personnel(artcc) - visual lookout - inadequate, pilot in command (contributing factor) - visual lookout - inadequate, pilot of other aircraft (contributing factor) - In flight collision with terrain/water, descent - uncontrolled - Midair collision, descent - normal - radar assistance to vfr aircraft - not used, pilot in command (cause) - artcc service - delayed, pilot of other aircraft (cause) - radar separation - not possible, atc personnel(artcc) - visual lookout - inadequate, pilot in command (contributing factor) - visual lookout - inadequate, pilot of other aircraft (contributing factor) - In flight collision with terrain/water, descent - uncontrolled ## Analysis (aircraft 2) AT ABOUT 1118, A BEECH C-99 (WINGS WEST FLT 628), N6399U, & A ROCKWELL 112TC, N112SM, COLLIDED IN MIDAIR APRX 8 MI WEST-NORTHWEST OF THE SAN LOUI OBISPO COUNTY ARPT. THE ROCKWELL 112TC HAD DEPARTED PASO ROBLES, CA & WAS DESCENDING TOWARD THE SAN LOUI OBISPO COUNTY ARPT. THE BEECH C-99 HAD DEPARTED SAN LOUI OBISPO & WAS CLIMBING ON A FLT TO SAN FRANCISCO. THEY COLLIDED HEAD-ON AT ABOUT 3400 FT MSL IN CLEAR WX. THE C-99 CREW HAD JUST CONTACTED LOS ANGELES ARTCC. AT THAT TIME, THE AIRCREWS OF BOTH ACFT WERE GOVERNED BY THE 'SEE-AND-AVOID' CONCEPT WITH REGARD TO EACH OTHER. AN INVESTIGATIONREVEALED THAT THE STANDARD DEPARTURE & INSTRUMENT APCH PROCEDURES SHARED A COMMON TRACK. THE C-99 WAS DEPARTING ALONG THE DEPARTURE TRACK. JUST PRIOR TO THE COLLISION, THE 112TC CREW HAD CONTACTED UNICOM & REPORTED AT THE DOBRA INTER- SECTION WHICH WAS ON THE ILS APCH COURSE. AFTER COLLIDING, BOTH ACFT CRASHED ON OPEN TERRAIN & BURNED. THE CONTROLLER HAD ONLY SECONDS TO APPRAISE RADAR DATA & ISSUE A SAFETY ADVISORY. WINGS WEST REQD 1 RADIO TO BE TUNED TO COMPANY FREQ. ## Analysis (aircraft 1) AT ABOUT 1118, A BEECH C-99 (WINGS WEST FLT 628), N6399U, & A ROCKWELL 112TC, N112SM, COLLIDED IN MIDAIR ABOUT 8 MI WEST-NORTHWEST OF THE SAN LOUI OBISPO COUNTY ARPT. THE ROCKWELL 112TC HAD DEPARTED PASO ROBLES, CA & WAS DESCENDING TOWARD THE SAN LOUI OBISPO COUNTY ARPT. THE BEECH C-99 HAD DEPARTED SAN LOUI OBISPO & WAS CLIMBING ON A FLT TO SAN FRANCISCO. THEY COLLIDED HEAD-ON AT ABOUT 3400 FT MSL IN CLEAR WX. THE C-99 CREW HAD JUST CONTACTED LOS ANGELES ARTCC. AT THAT TIME, THE AIRCREWS OF BOTH ACFT WERE GOVERNED BY THE 'SEE-AND-AVOID' CONCEPT WITH REGARD TO EACH OTHER. AN INVESTIGATION REVEALED THAT THE STANDARD DEPARTURE & INSTRUMENT APCH PROCEDURES SHARED A COMMON TRACK. THE C-99 WAS DEPARTING ALONG THE DEPARTURE TRACK. JUST PRIOR TO THE COLLISION, THE 112TC CREW HAD CONTACTED UNICOM & REPORTED AT THE DOBRA INTERSECTION WHICH WAS ON THE ILS APCH COURSE. AFTER COLLIDING, BOTH ACFT CRASHED ON OPEN TERRAIN & BURNED. THE CONTROLLER HAD ONLY SECONDS TO APPRAISE RADAR DATA & ISSUE A SAFETY ADVISORY. WINGS WEST REQD 1 RADIO ON COMPANY FREQ. ## Aircraft 1 - Registration: N6399U (not matched to a registry record) - Reported make and model: BEECH C-99 - Category: Airplane - Serial number: U-187 - Engines: P&W PT6A 550 horsepower turbo prop - Damage: Destroyed - Fire: On-Ground - Flight: Part 135 - Operator: Wings West Airlines, Inc. - Registered owner: Capital Equipment Co. - Departed: SAN LUIS OBISPO, CA - Destination: SAN FRANCISCO, CA - Flight plan: IFR - Airport: SBP, San Loui Obispo ## Aircraft 2 - Registration: N112SM (not matched to a registry record) - Reported make and model: Rockwell 112TC - Category: Airplane - Serial number: 13020 - Engines: LYCOMING TO-360 210 horsepower reciprocating - Damage: Destroyed - Fire: On-Ground - Flight: Instructional, Part 91 - Registered owner: Aesthetech Corp. - Airworthiness certificate: Standard, Normal - Departed: PASO ROBLES, CA - Airport: SBP, San Loui Obispo ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot, aircraft N6399U; age 28; airline transport, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; flight hours: 4,110 total, 873 in this make and model, 271 in the last 90 days, 91 in the last 30 days, 4 in the last 24 hours - Pilot, aircraft N112SM; age 58; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; flight hours: 4,858 total, 73 in this make and model, 251 in the last 90 days, 93 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 240° at 3 knots - Visibility: 15 statute miles - Lowest ceiling: none - Temperature: 75 °F, dew point -0 °F ## FAA reports on this event (2) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 19840824076851A](https://openairdocs.org/incident/19840824076851A), Aug 24, 1984: Beech C99, San Luis Obispo, CA, Destroyed, 13 fatal. Collided head on with N112SM while climbing. Impacted ground and burned. Had quit monitoring UNICOM frequency. - [Accident 19840824076852A](https://openairdocs.org/incident/19840824076852A), Aug 24, 1984: Gulstm 112TC, San Luis Obispo, CA, Destroyed. Collided head on with N6399U while descending. Impacted ground. Failed to see and avoid collision. ATC not used. 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.