Potential conflict ensues as pilot, flight crew and controller misjudge traffic spacing.

Attributes
ACN	174518
Time
Date	199104
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bur
State Reference	CA
Altitude	msl bound lower : 5300 msl bound upper : 5500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bur
Operator	common carrier : air taxi
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Retractable Gear
Flight Phase	cruise other
Flight Plan	VFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air taxi
Function	flight crew : single pilot
Qualification	pilot : atp pilot : cfi
Experience	flight time last 90 days : 250 flight time total : 2300 flight time type : 800
ASRS Report	174518
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : far other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 2000 vertical : 500
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Flying east en route oxr-emt with radar advisories. Bur advised that an air carrier medium large transport would be departing bur and turning northwest restr to 5000'. My reply was, 'roger, traffic in sight. 20-30 seconds later I called and said, 'bur, small aircraft X (our flight #) would like to begin descent when air carrier goes by.' bur replied, 'traffic at 12 O'clock will be turning northwest.' then, 'air carrier Y, turn 320 degrees, continue climb.' 'small aircraft flight, keep traffic in sight. Descend pilot's discretion.' I began descent and began trying to judge the turn and climb of the jet. At 5300' I decided that there may be a problem. We were doing about 150 KTS. ATC called the air carrier jet and told him to turn right 340 degrees and may have given him our position. At this point it was evident if I continued on heading east there would be a problem, regardless of altitude, so I turned right to south for a few seconds, then back on course. The air carrier medium large transport advised that it was a little closer than they liked. ATC should not have told air carrier to continue climb or authority/authorized my descent.

Original NASA ASRS Text

Title: POTENTIAL CONFLICT ENSUES AS PLT, FLT CREW AND CTLR MISJUDGE TRAFFIC SPACING.

Narrative: FLYING E ENRTE OXR-EMT WITH RADAR ADVISORIES. BUR ADVISED THAT AN ACR MLG WOULD BE DEPARTING BUR AND TURNING NW RESTR TO 5000'. MY REPLY WAS, 'ROGER, TFC IN SIGHT. 20-30 SECS LATER I CALLED AND SAID, 'BUR, SMA X (OUR FLT #) WOULD LIKE TO BEGIN DSNT WHEN ACR GOES BY.' BUR REPLIED, 'TFC AT 12 O'CLOCK WILL BE TURNING NW.' THEN, 'ACR Y, TURN 320 DEGS, CONTINUE CLB.' 'SMA FLT, KEEP TFC IN SIGHT. DSND PLT'S DISCRETION.' I BEGAN DSNT AND BEGAN TRYING TO JUDGE THE TURN AND CLB OF THE JET. AT 5300' I DECIDED THAT THERE MAY BE A PROB. WE WERE DOING ABOUT 150 KTS. ATC CALLED THE ACR JET AND TOLD HIM TO TURN RIGHT 340 DEGS AND MAY HAVE GIVEN HIM OUR POS. AT THIS POINT IT WAS EVIDENT IF I CONTINUED ON HDG E THERE WOULD BE A PROB, REGARDLESS OF ALT, SO I TURNED RIGHT TO S FOR A FEW SECS, THEN BACK ON COURSE. THE ACR MLG ADVISED THAT IT WAS A LITTLE CLOSER THAN THEY LIKED. ATC SHOULD NOT HAVE TOLD ACR TO CONTINUE CLB OR AUTH MY DSNT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.