Instead of refuelling and waiting for the wash of this run to subside, Campbell decided to make the return run immediately. This was not an unprecedented diversion from normal practice, as Campbell had used the advantage presented i.e. no encroachment of water disturbances on the measured kilometre by the quick turn-a-round, in many previous runs. The second run was even faster once severe tramping subsided on the run-up from Peel Island (caused by the water-brake disturbance). Once smooth water was reached some or so from the start of the kilometre, K7 demonstrated cycles of ground effect hovering before accelerating hard at 0.63 g to a peak speed of some 200 metres or so from the southern marker buoy. "Bluebird" was now experiencing bouncing episodes of the starboard sponson with increasing ferocity. At the peak speed, the most intense and long-lasting bounce precipitated a severe decelerating episode — to , -1.86g — as "K7" dropped back onto the water. Engine flame-out then occurred and, shorn of thrust nose-down momentum, K7 experienced a gliding episode in strong ground effect with increasing angle-of-attack, before completely leaving the water at her static stability pitch-up limit of 5.2°. "Bluebird" then executed an almost complete somersault (~ 320° and slightly off-axis) before plunging into the water (port sponson marginally in advance of the starboard), approximately 230 metres from the end of the measured kilometre. The boat then cartwheeled across the water before coming to rest. The impact broke "K7" forward of the air intakes (where Campbell was sitting) and the main hull sank shortly afterwards.