question: invert the speed value , for example when vertical speeds are positive downwards concode_field_sep boolean _valid concode_elem_sep double _value concode_elem_sep Unit _unit concode_field_sep double getValue concode_elem_sep double getValue concode_elem_sep boolean isValidUnit concode_elem_sep boolean isValid concode_elem_sep Unit getUnit concode_elem_sep double getValueInMetresPerSec concode_elem_sep void copyFrom
target: void function ( ) { if ( _valid ) _value = - _value ; }