Medium Large Transport; Low Wing; 2 Turbojet Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 4.0
Communication Breakdown; Distraction; Situational Awareness; Training / Qualification; Workload
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance
Airspace Structure; Human Factors; Procedure
I was training a developmental when he had a few arrivals into 2 different airports. Aircraft X was inbound from the North into GSP and there was another arrival from the West landing at a controlled satellite airport. The controller working the East sector also had 2 arrivals into the satellite airport. Originally Aircraft X was given a decent to 5;000 and a 190 heading to keep him clear of the other controllers arrivals. The controller at the satellite airport called over on the shout line and was switching runways when one arrival was on a short final. After coordinating the runway change with the other East controller; the trainee went to descend Aircraft X; but I told him to descend another satellite arrival. Since I was talking; I missed the altitude assignment and read back for Aircraft X; but I incorrectly assumed the altitude assigned was 4;000. The trainee descended him to 3;000 in a 3;500 MVA with Aircraft Y within 3 miles at 3;000 slowly descending into the satellite airport. I missed the altitude assignment because I was telling the trainee to do something else. I have no overreaching recommendations; but for myself I will not tell the trainee something while they are giving a control instruction.
TRACON Controller reported they were distracted and did not hear their Trainee assign an aircraft an altitude below the Minimum Vectoring Altitude.