Non adherence to ATC clearance. Descent from assigned altitude. Pilot deviation.

Attributes
ACN	141259
Time
Date	199004
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : ubg
State Reference	OR
Altitude	msl bound lower : 2300 msl bound upper : 4000
Environment
Flight Conditions	Marginal
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : pdx
Make Model Name	Small Aircraft
Flight Phase	cruise other descent : approach descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller military : 6 controller radar : 12
ASRS Report	141259
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance non adherence : published procedure other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Aircraft was inbound to hio V495 ubg direct hio at 6000'! Pilot reported over ubg VOR when he was actually 6 mi south. I told him to fly heading 330 degree vectors to ILS runway 12 final approach course hio descend and maintain 4000'. I later advised the pilot that when he called over ubg he was actually 6 mi south. A few mins later I noticed I was starting to lose radar with the aircraft and I shouldn't have been. (Northwest of ubg there is no radar coverage below 3700'). I asked the pilot to say altitude. He said he was 2300' descending on the G/south. I told him to climb immediately to 4000'. Once he was level at 4000' and on his assigned heading, I told him he was 6 mi southwest of hio on downwind at 4000' so he could establish exactly where he was at in his own mind. On downwind, I assigned him 3500'. He busted that altitude and was at 2900' before I could stop him descending further and get him back up to 3500'. The pilot eventually completed the approach and landed safely. My guess is that he had low time in type (couldn't keep up with airplane) and not very proficient at instrument flying.

Original NASA ASRS Text

Title: NON ADHERENCE TO ATC CLRNC. DESCENT FROM ASSIGNED ALT. PLTDEV.

Narrative: ACFT WAS INBND TO HIO V495 UBG DIRECT HIO AT 6000'! PLT RPTED OVER UBG VOR WHEN HE WAS ACTUALLY 6 MI S. I TOLD HIM TO FLY HDG 330 DEG VECTORS TO ILS RWY 12 FINAL APCH COURSE HIO DSND AND MAINTAIN 4000'. I LATER ADVISED THE PLT THAT WHEN HE CALLED OVER UBG HE WAS ACTUALLY 6 MI S. A FEW MINS LATER I NOTICED I WAS STARTING TO LOSE RADAR WITH THE ACFT AND I SHOULDN'T HAVE BEEN. (NW OF UBG THERE IS NO RADAR COVERAGE BELOW 3700'). I ASKED THE PLT TO SAY ALT. HE SAID HE WAS 2300' DSNDING ON THE G/S. I TOLD HIM TO CLB IMMEDIATELY TO 4000'. ONCE HE WAS LEVEL AT 4000' AND ON HIS ASSIGNED HDG, I TOLD HIM HE WAS 6 MI SW OF HIO ON DOWNWIND AT 4000' SO HE COULD ESTABLISH EXACTLY WHERE HE WAS AT IN HIS OWN MIND. ON DOWNWIND, I ASSIGNED HIM 3500'. HE BUSTED THAT ALT AND WAS AT 2900' BEFORE I COULD STOP HIM DSNDING FURTHER AND GET HIM BACK UP TO 3500'. THE PLT EVENTUALLY COMPLETED THE APCH AND LANDED SAFELY. MY GUESS IS THAT HE HAD LOW TIME IN TYPE (COULDN'T KEEP UP WITH AIRPLANE) AND NOT VERY PROFICIENT AT INSTRUMENT FLYING.

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.