Cpr Y unauthorized descent to occupied altitude had less than standard separation from atx X. Pilot ...

Attributes
ACN	242689
Time
Date	199305
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : dfw
State Reference	TX
Altitude	msl bound lower : 4000 msl bound upper : 5000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : dfw
Operator	common carrier : air taxi
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	general aviation : corporate
Make Model Name	Light Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller radar : 12
ASRS Report	242689
Person 2
Affiliation	company : air taxi
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : overshoot conflict : airborne less severe non adherence : clearance non adherence : required legal separation
Resolutory Action	aircraft : equipment problem dissipated
Consequence	faa : reviewed incident with flight crew Other
Miss Distance	horizontal : 3000 vertical : 200
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Atx, eastbound, leaves at 4000 ft on ATC clearance. Cpr Y was on a vector to runway 31R at dfw. Cpr Y was issued clearance to maintain 5000 ft. Cpr Y descended on his own through 5000 ft to 4000 ft. I issued an immediate descend clearance to atx X and obtained visual separation. The aircraft came within 1/2 mi and 200 ft.

Original NASA ASRS Text

Title: CPR Y UNAUTH DSCNT TO OCCUPIED ALT HAD LTSS FROM ATX X. PLTDEV.

Narrative: ATX, EBOUND, LEAVES AT 4000 FT ON ATC CLRNC. CPR Y WAS ON A VECTOR TO RWY 31R AT DFW. CPR Y WAS ISSUED CLRNC TO MAINTAIN 5000 FT. CPR Y DSNDED ON HIS OWN THROUGH 5000 FT TO 4000 FT. I ISSUED AN IMMEDIATE DSND CLRNC TO ATX X AND OBTAINED VISUAL SEPARATION. THE ACFT CAME WITHIN 1/2 MI AND 200 FT.

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.

Cpr Y unauthorized descent to occupied altitude had less than standard separation from atx X. Pilot deviation.