Air carrier X descent below MVA had conflict with radio antennas. System error.

Attributes
ACN	258588
Time
Date	199312
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : tul
State Reference	OK
Altitude	msl bound lower : 2500 msl bound upper : 2500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : tul
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other 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 : 6
ASRS Report	258588
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument
Events
Anomaly	altitude deviation : overshoot non adherence : published procedure non adherence : clearance other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Operational Error Pilot Deviation

Narrative:

I was working combined radar west and east at tul, when I took a handoff on small aircraft X, IFR level at 6000 ft. Small aircraft X was landing at rvs, a satellite field. I descended the small aircraft X to 4000 ft after a few mins. In the meantime, I became pretty busy with aircraft stepping on each other on the 4 frequencys I was monitoring. I descended small aircraft X to 3500 ft and put him on a vector first officer 240 degrees, 3500 ft is the MVA in the area. Small aircraft X was basically all the traffic I had in the southeast quadrant. I was pretty busy at this time with most of my traffic west and north. Another controller assisted in some coordination and when I asked to split the sectors the controller had already stepped out. Small aircraft X then called and asked if he could make a right turn around the antennas. At this moment, I noticed he was at 2500 ft (the antenna ht), I climbed small aircraft X and turned him away from the antennas. He was approximately 2 1/2 mi east of the antennas at this point. I reminded small aircraft X his assigned altitude was 3500 ft, and the pilot said it was 2500 ft. Small aircraft X reached 3500 ft and was revectored toward rvs. I do not know if the pilot missed his altitude in descent (deviated) or if I missed an incorrect readback. I do know without a doubt that I assigned him 3500 ft.

Original NASA ASRS Text

Title: ACR X DSCNT BELOW MVA HAD CONFLICT WITH RADIO ANTENNAS. SYS ERROR.

Narrative: I WAS WORKING COMBINED RADAR W AND E AT TUL, WHEN I TOOK A HDOF ON SMA X, IFR LEVEL AT 6000 FT. SMA X WAS LNDG AT RVS, A SATELLITE FIELD. I DSNDED THE SMA X TO 4000 FT AFTER A FEW MINS. IN THE MEANTIME, I BECAME PRETTY BUSY WITH ACFT STEPPING ON EACH OTHER ON THE 4 FREQS I WAS MONITORING. I DSNDED SMA X TO 3500 FT AND PUT HIM ON A VECTOR FO 240 DEGS, 3500 FT IS THE MVA IN THE AREA. SMA X WAS BASICALLY ALL THE TFC I HAD IN THE SE QUADRANT. I WAS PRETTY BUSY AT THIS TIME WITH MOST OF MY TFC W AND N. ANOTHER CTLR ASSISTED IN SOME COORD AND WHEN I ASKED TO SPLIT THE SECTORS THE CTLR HAD ALREADY STEPPED OUT. SMA X THEN CALLED AND ASKED IF HE COULD MAKE A R TURN AROUND THE ANTENNAS. AT THIS MOMENT, I NOTICED HE WAS AT 2500 FT (THE ANTENNA HT), I CLBED SMA X AND TURNED HIM AWAY FROM THE ANTENNAS. HE WAS APPROX 2 1/2 MI E OF THE ANTENNAS AT THIS POINT. I REMINDED SMA X HIS ASSIGNED ALT WAS 3500 FT, AND THE PLT SAID IT WAS 2500 FT. SMA X REACHED 3500 FT AND WAS REVECTORED TOWARD RVS. I DO NOT KNOW IF THE PLT MISSED HIS ALT IN DSCNT (DEVIATED) OR IF I MISSED AN INCORRECT READBACK. I DO KNOW WITHOUT A DOUBT THAT I ASSIGNED HIM 3500 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.