Aircraft X unauthorized climb from assigned altitude had less than standard separation from aircraft...

Attributes
ACN	273868
Time
Date	199406
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : gsb
State Reference	NC
Altitude	msl bound lower : 15000 msl bound upper : 16000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : tul
Operator	general aviation : personal
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Route In Use	enroute : direct enroute airway : zdc
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 12
ASRS Report	273868
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : required legal separation non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem flight crew : returned to intended course or assigned course
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 21000 vertical : 600
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

Aircraft X was on my frequency level at 15000 ft and on a direct course nebound. I issued traffic Y to X sebound at 16000 ft. X climbed to 15400 ft and stated his autoplt had initiated the climb. Lately, in the en route environment, I have noticed frequently that when aircraft are issued TA's they frequently bust their altitude. I have no explanation for this.

Original NASA ASRS Text

Title: ACFT X UNAUTH CLB FROM ASSIGNED ALT HAD LTSS FROM ACFT Y. PLTDEV.

Narrative: ACFT X WAS ON MY FREQ LEVEL AT 15000 FT AND ON A DIRECT COURSE NEBOUND. I ISSUED TFC Y TO X SEBOUND AT 16000 FT. X CLBED TO 15400 FT AND STATED HIS AUTOPLT HAD INITIATED THE CLB. LATELY, IN THE ENRTE ENVIRONMENT, I HAVE NOTICED FREQUENTLY THAT WHEN ACFT ARE ISSUED TA'S THEY FREQUENTLY BUST THEIR ALT. I HAVE NO EXPLANATION FOR THIS.

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.

Aircraft X unauthorized climb from assigned altitude had less than standard separation from aircraft Y. Pilot deviation.