Cpr X descent to occupied altitude had less than standard separation from cpr Y. System error.

Attributes
ACN	218814
Time
Date	199208
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : mkl
State Reference	TN
Altitude	msl bound lower : 21000 msl bound upper : 21000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zme
Operator	general aviation : corporate
Make Model Name	Light Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	general aviation : corporate
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
ASRS Report	218814
Person 2
Affiliation	government : faa
Function	oversight : supervisor
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation other anomaly other
Independent Detector	atc equipment other atc equipment : unspecified
Resolutory Action	controller : issued new clearance other
Consequence	faa : investigated
Miss Distance	horizontal : 18000 vertical : 500
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

After I took sector 7, I noticed a low and weak audible in my headset or the equipment, so I took a couple of frequencys check to see if it was me or the equipment. After receiving poor responses, I requested my supervisor to change headsets for me. Even with the new headset, I noticed that I had the same problem of hearing. I tried in vain to work out this problem with hope that it would disappear, however, I was covered up at this time and I needed to stay in sector 7 to work out the numerous situations. I had to constantly repeat myself because I wasn't sure of what I was hearing also. At the time when cpr X read my instruction back to me the clarity in my headset wasn't good enough to hear or understand what he said. I was further distracted by a call from sector 26. Before I could get back to cpr X to verify my clearance, he had started his descent. I immediately issued clearance to cpr X to maintain FL210.

Original NASA ASRS Text

Title: CPR X DSCNT TO OCCUPIED ALT HAD LTSS FROM CPR Y. SYS ERROR.

Narrative: AFTER I TOOK SECTOR 7, I NOTICED A LOW AND WEAK AUDIBLE IN MY HEADSET OR THE EQUIP, SO I TOOK A COUPLE OF FREQS CHK TO SEE IF IT WAS ME OR THE EQUIP. AFTER RECEIVING POOR RESPONSES, I REQUESTED MY SUPVR TO CHANGE HEADSETS FOR ME. EVEN WITH THE NEW HEADSET, I NOTICED THAT I HAD THE SAME PROBLEM OF HEARING. I TRIED IN VAIN TO WORK OUT THIS PROBLEM WITH HOPE THAT IT WOULD DISAPPEAR, HOWEVER, I WAS COVERED UP AT THIS TIME AND I NEEDED TO STAY IN SECTOR 7 TO WORK OUT THE NUMEROUS SITUATIONS. I HAD TO CONSTANTLY REPEAT MYSELF BECAUSE I WASN'T SURE OF WHAT I WAS HEARING ALSO. AT THE TIME WHEN CPR X READ MY INSTRUCTION BACK TO ME THE CLARITY IN MY HEADSET WASN'T GOOD ENOUGH TO HEAR OR UNDERSTAND WHAT HE SAID. I WAS FURTHER DISTRACTED BY A CALL FROM SECTOR 26. BEFORE I COULD GET BACK TO CPR X TO VERIFY MY CLRNC, HE HAD STARTED HIS DSCNT. I IMMEDIATELY ISSUED CLRNC TO CPR X TO MAINTAIN FL210.

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.