double PerformanceData::actualVerticalSpeed(FGAIAircraft* ac, double tgt_vs, double dt) {
double vs = ac->getVerticalSpeed();
double vs_diff = tgt_vs - vs;
double PerformanceData::actualVerticalSpeed(FGAIAircraft* ac, double tgt_vs, double dt) {
double vs = ac->getVerticalSpeed();
double vs_diff = tgt_vs - vs;