The modification of a magnetic sector mass spectrometer to provide measurement of Ion flight time results in a novel instrument which can provide all the data presently obtained from tandem MS/MS instrumentation. The combination of ion momentum and velocity analysis provides unambiguous mass assignments for parent and daughter ions while flight time comparison establishes parent-daughter relationships. Data has been obtained from a modified LKB-9000 which demonstrates the feasibility of this technique. Suggestions for an upgraded instrument wlth automated scanning are made and the possibility of achieving full MS/MS data collection on the chromatographic time scale through the use of an integrating transient recorder is presented.