Abstract: A fluid flow diverter system for use with twin engine vertical take-off aircraft. The diverter sysstem is employed to direct a portion of, or all, the working fluid from the first axial flow compressor (14) of either a by-pass engine, a twin fan engine or a variable cycle engine to either a pair of vectorable front nozzles (36) or to a by-pass duct (34). In the event of one engine failing in flight, an attempt at balancing the remaining thrust for vertical landing is made by ducting all the air normally existing from the operative engine's front nozzle (36) across to the inoperative engine's front nozzle (36).