Small aircraft X had near midair collision with small aircraft Y. See and avoid concept.

Attributes
ACN	163107
Time
Date	199011
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : dvt
State Reference	AZ
Altitude	agl bound lower : 1000 agl bound upper : 1000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : dvt tower : ftw
Operator	general aviation : personal
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	climbout : intermediate altitude
Flight Plan	None
Aircraft 2
Operator	other
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Retractable Gear
Flight Phase	other
Flight Plan	None
Person 1
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
Experience	controller non radar : 9
ASRS Report	163107
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private
Events
Anomaly	conflict : nmac
Independent Detector	other flight crewa
Resolutory Action	none taken : insufficient time
Consequence	Other
Miss Distance	vertical : 50
Supplementary
Primary Problem	ATC Human Performance

Narrative:

Small aircraft X departed runway 7R, northbound. Small aircraft Y departed runway 7L, left traffic. Both aircraft on upwind. Small aircraft Y is further east. I told small aircraft X, 'traffic, small aircraft Y ahead to your left on upwind remaining in left traffic, begin left turn now.' small aircraft X acknowledged and had traffic in sight. Small aircraft X turned north and small aircraft Y began his left crosswind. As small aircraft Y began a left turn to the downwind, I issued traffic to him: 'traffic, small aircraft X ahead, to your left, northbound, will pass above you.' the situation looked ok, so I diverted my attention to the traffic in the south pattern. Approximately 1 min later the instrument in small aircraft Y said they had the traffic 'now, he just passed over the top of us and that was way too close.' small aircraft Y and small aircraft X pilots then had their own conversation on the frequency, for 4 or 5 xmissions each, about how close they thought they were.

Original NASA ASRS Text

Title: SMA X HAD NMAC WITH SMA Y. SEE AND AVOID CONCEPT.

Narrative: SMA X DEPARTED RWY 7R, NBND. SMA Y DEPARTED RWY 7L, LEFT TFC. BOTH ACFT ON UPWIND. SMA Y IS FURTHER E. I TOLD SMA X, 'TFC, SMA Y AHEAD TO YOUR LEFT ON UPWIND REMAINING IN LEFT TFC, BEGIN LEFT TURN NOW.' SMA X ACKNOWLEDGED AND HAD TFC IN SIGHT. SMA X TURNED N AND SMA Y BEGAN HIS LEFT XWIND. AS SMA Y BEGAN A LEFT TURN TO THE DOWNWIND, I ISSUED TFC TO HIM: 'TFC, SMA X AHEAD, TO YOUR LEFT, NBND, WILL PASS ABOVE YOU.' THE SITUATION LOOKED OK, SO I DIVERTED MY ATTN TO THE TFC IN THE S PATTERN. APPROX 1 MIN LATER THE INSTR IN SMA Y SAID THEY HAD THE TFC 'NOW, HE JUST PASSED OVER THE TOP OF US AND THAT WAS WAY TOO CLOSE.' SMA Y AND SMA X PLTS THEN HAD THEIR OWN CONVERSATION ON THE FREQ, FOR 4 OR 5 XMISSIONS EACH, ABOUT HOW CLOSE THEY THOUGHT THEY WERE.

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.