Narrative:

Air carrier X departed alo airport, flight plan route alo...dbq. I told pilot radar contact, turn left heading 090 degrees until able direct dbq climb and maintain 9000 ft. Pilot asked if they could fly a seasterly heading for WX deviation and I approved it. Shortly thereafter, pilot requested 3000 ft or 5000 ft to stay below clouds. I asked which they preferred, 3000 ft or 5000 ft. Pilot requested 3000 ft. I cleared aircraft to maintain 3000 ft. After some flying time while I was busy at the fdio (computer terminal for entering flight plan information) the pilot called and said there was a tall tower just ahead. I looked at his position on the scope and realized the deviation the pilot took got them into an area where the MVA is 4000 ft due to the tv tower. I told pilot to turn left immediately and pilot replied they were turning right to miss the tower. I approved the right turn and once they were past the tower pilot requested climb to 5000 ft. I issued climb and maintain 5000 ft. Pilot asked if there were any more towers in area and I told them there were 2 more towers 6 mi south and no more obstructions east of their position. Rest of flight out of my airspace was uneventful. I feel there were several factors that led to this event. 1) my being distracted by entering information into the fdio and taking my eyes off the scope. 2) the software for our ARTS iia program is supposed to have a low altitude warning alarm that would be triggered if someone is below the MVA in that area. The alarm never went off. 3) I should have just issued 5000 ft to the pilot to begin with to avoid any such occurrence. 4) by the pilot being on own navigation to fly however far off the flight plan route they wanted to deviate for WX.

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Original NASA ASRS Text

Title: ACR X ASSIGNED ALT BELOW MVA. OPDEV.

Narrative: ACR X DEPARTED ALO ARPT, FLT PLAN RTE ALO...DBQ. I TOLD PLT RADAR CONTACT, TURN L HDG 090 DEGS UNTIL ABLE DIRECT DBQ CLB AND MAINTAIN 9000 FT. PLT ASKED IF THEY COULD FLY A SEASTERLY HDG FOR WX DEV AND I APPROVED IT. SHORTLY THEREAFTER, PLT REQUESTED 3000 FT OR 5000 FT TO STAY BELOW CLOUDS. I ASKED WHICH THEY PREFERRED, 3000 FT OR 5000 FT. PLT REQUESTED 3000 FT. I CLRED ACFT TO MAINTAIN 3000 FT. AFTER SOME FLYING TIME WHILE I WAS BUSY AT THE FDIO (COMPUTER TERMINAL FOR ENTERING FLT PLAN INFO) THE PLT CALLED AND SAID THERE WAS A TALL TWR JUST AHEAD. I LOOKED AT HIS POS ON THE SCOPE AND REALIZED THE DEV THE PLT TOOK GOT THEM INTO AN AREA WHERE THE MVA IS 4000 FT DUE TO THE TV TWR. I TOLD PLT TO TURN L IMMEDIATELY AND PLT REPLIED THEY WERE TURNING R TO MISS THE TWR. I APPROVED THE R TURN AND ONCE THEY WERE PAST THE TWR PLT REQUESTED CLB TO 5000 FT. I ISSUED CLB AND MAINTAIN 5000 FT. PLT ASKED IF THERE WERE ANY MORE TWRS IN AREA AND I TOLD THEM THERE WERE 2 MORE TWRS 6 MI S AND NO MORE OBSTRUCTIONS E OF THEIR POS. REST OF FLT OUT OF MY AIRSPACE WAS UNEVENTFUL. I FEEL THERE WERE SEVERAL FACTORS THAT LED TO THIS EVENT. 1) MY BEING DISTRACTED BY ENTERING INFO INTO THE FDIO AND TAKING MY EYES OFF THE SCOPE. 2) THE SOFTWARE FOR OUR ARTS IIA PROGRAM IS SUPPOSED TO HAVE A LOW ALT WARNING ALARM THAT WOULD BE TRIGGERED IF SOMEONE IS BELOW THE MVA IN THAT AREA. THE ALARM NEVER WENT OFF. 3) I SHOULD HAVE JUST ISSUED 5000 FT TO THE PLT TO BEGIN WITH TO AVOID ANY SUCH OCCURRENCE. 4) BY THE PLT BEING ON OWN NAV TO FLY HOWEVER FAR OFF THE FLT PLAN RTE THEY WANTED TO DEVIATE FOR WX.

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.