Small Aircraft; High Wing; 1 Eng; Fixed Gear
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 3
Communication Breakdown
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance
Procedure; Human Factors
Aircraft X was taking off Runway 35L runway heading and Aircraft Y was straight out Runway 35R. I was training on VR and we decided to keep Aircraft X [on] runway heading until the Aircraft Y turned east to avoid wake turbulence. When Aircraft Y turned eastbound; we turned Aircraft X on a 130 degree heading initially at or below 8;500 feet MSL; then amended it to a 100 degree heading to clear the departure corridor. We kept Aircraft X at or below 8;500 feet MSL just as we were entering a 8;900 feet MSL MVA; however; Aircraft X was issued headings prior to entering the 8;900 feet MVA to stay in the 8;400 feet MVA. Better airspace/MVA awareness; better awareness on the Tower when departing eastbound VFR departures reference departures on Runway 35R.
COS TRACON Controller reported an MVA violation.