the belly of the passenger 2 the dorsal part also comprises at least two dorsal straps 14 which can be applied on the back of the passenger 2 the main harness 3 and the secondary harness 4 are connected with each other by a snap 18 provided on the secondary harness 4 which snap is fixing to a ring 6 provided on the main harness 3 and for an accommodation of the fasteners of the secondary harness 4 the anchorage of the snap 18 is conventionally done at the ring 6 positioned such that as commonly known the pilot 1 ensures the anchorage of the secondary harness 4 of the passenger 2 the dorsal part and the frontal part of the secondary harness 4 are maintained spaced apart by means to maintain a spacing advantageously these means are a rigid spacer element 5 arranged transversally between both parts the passenger 2 has the dorsal and frontal parts spaced apart by the spacer element 5 and thus equally biased by the front and the back due to the tensile action associated with the support of the spacer element 5 the spacer element 5 shown consists of a single rigid and resistant elongated piece to ensure the spacing of the dorsal and frontal parts of the.