Approach controller descends air carrier through altitude of VFR aircraft.

Attributes
ACN	317760
Time
Date	199510
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : las
State Reference	NV
Altitude	msl bound lower : 7500 msl bound upper : 7500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : las
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent other
Route In Use	arrival other arrival star : star enroute other
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Turbo (Jet) Prop
Operating Under FAR Part	Part 91
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : on vectors
Flight Plan	VFR
Person 1
Affiliation	government : faa
Function	controller : approach oversight : supervisor
Qualification	controller : radar
Experience	controller military : 4 controller non radar : 2 controller radar : 14
ASRS Report	317760
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : developmental
Experience	controller military : 4 controller non radar : 3 controller radar : 4
ASRS Report	317761
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation other anomaly other
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance none taken : detected after the fact other
Consequence	Other
Miss Distance	horizontal : 6000 vertical : 300
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

I was instructing my trainee at the time and I believed I heard her issue 8000 ft to an arriving jet. An AC69 was VFR opposite direction at 6500 ft requesting higher because of the rough ride. I instructed my trainee to climb the AC69 to 7500 ft. Traffic was issued. I observed the jet descending below 8000 ft and issued immediate climb instructions. (Ineffective listening techniques.) supplemental information from acn 317761: I was training on the arrival position. I descended the B737 to 7000 ft. The VFR AC69 called at 6500 ft requesting a higher altitude. My instructor thought I issued 8000 ft to the B737 and told me to climb the AC69 to 7500 ft. I did as I was told thinking that maybe I did only go down to 8000 ft with the B737.

Original NASA ASRS Text

Title: APCH CTLR DSNDS ACR THROUGH ALT OF VFR ACFT.

Narrative: I WAS INSTRUCTING MY TRAINEE AT THE TIME AND I BELIEVED I HEARD HER ISSUE 8000 FT TO AN ARRIVING JET. AN AC69 WAS VFR OPPOSITE DIRECTION AT 6500 FT REQUESTING HIGHER BECAUSE OF THE ROUGH RIDE. I INSTRUCTED MY TRAINEE TO CLB THE AC69 TO 7500 FT. TFC WAS ISSUED. I OBSERVED THE JET DSNDING BELOW 8000 FT AND ISSUED IMMEDIATE CLB INSTRUCTIONS. (INEFFECTIVE LISTENING TECHNIQUES.) SUPPLEMENTAL INFO FROM ACN 317761: I WAS TRAINING ON THE ARR POS. I DSNDED THE B737 TO 7000 FT. THE VFR AC69 CALLED AT 6500 FT REQUESTING A HIGHER ALT. MY INSTRUCTOR THOUGHT I ISSUED 8000 FT TO THE B737 AND TOLD ME TO CLB THE AC69 TO 7500 FT. I DID AS I WAS TOLD THINKING THAT MAYBE I DID ONLY GO DOWN TO 8000 FT WITH THE B737.

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.