ASN Wikibase Occurrence # 37415
Last updated: 20 April 2014
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Date:24-AUG-1989
Time:0927
Type:Silhouette image of generic C180 model; specific model in this crash may look slightly different
Cessna 180J
Owner/operator:private
Registration: N42695
C/n / msn: 18052370
Fatalities:Fatalities: 2 / Occupants: 2
Other fatalities:0
Airplane damage: Written off (damaged beyond repair)
Location:Tracy, CA -   United States of America
Phase: En route
Nature:Private
Departure airport:San Rafael, CA
Destination airport:Fresno, CA (FAT)
Narrative:
BEECH 95 (N9750Y) WAS TRACKING SOUTH AT APRX 185 KTS AS CESSNA 180 (N42695) WAS TRACKING 118 DEG AT ABOUT 147 KTS. BOTH WERE IN VMC, RCVG RADAR SVC (VFR FLT FLWG) FM STOCKTON TRACON. DRG AUTOMATED RADAR HANDOFFS TO TRACY SECTOR (TR) CTLR, THE PLTS RPRTD AT 5500' MSL. SUBSEQUENTLY, THE 2 ACFT CONVERGED, COLLIDED AT ABOUT 5500' MSL, THEN CRASHED IN UNCTLD DSCNTS. THE CTLR WAS OCCUPIED WITH CTLG 2 OTR ACFT. BOTH WERE OPERG UNDER IFR & REQUIRED HIS ATTN TO MAINT SEPN. THE COLLISION OCCURRED AS THE CTLR WAS CONCENTRATING ON SEPN OF THE 2 IFR ACFT. N9750Y CONVERGED ON N42695 FROM THE NE (APRX70 DEG LEFT OF N42695'S NOSE). N42695 CONVERGED ON N9750Y FM THE SW (APRX 48 DEG RGT OF N9750Y'S NOSE). THE CTLR WAS NOTAWARE OF THE COLLISION UNTIL LATER. THE STOCKTON ARTS II RADAR WAS NOT EQUIPPED WITH A CONFLICT ALERT SYS. THE ARTS II RADAR WAS PROGRAMMED TO MOVE NO BEACON (VFR) CALL SIGNS TO THE TAB LIST AFTER NOT RCVG A TRANSPONDER REPLY FOR 5 SCANS (APRX 20 SEC). AFTER AN ADNL 33 SCANS (A TOTAL OF APRX 2.5 MIN), THE CALL SIGN WOULD DISAPPEAR FM THE TAB LIST, AS WELL. CAUSE: INADEQUATE VISUAL LOOKOUT BY BOTH PILOTS, WHICH RESULTED IN THEIR FAILURE TO SEE-AND-AVOID EACH OTHER'S AIRCRAFT. A FACTOR RELATED TO THE ACCIDENT WAS: THE LACK OF A CONFLICT ALERT SYSTEM FOR THE STOCKTON ARTS II RADAR.

Sources:
NTSB: http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001213X29141


Revision history:

Date/timeContributorUpdates
24-Oct-2008 10:30 ASN archive Added
Number of views: 684

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