In accidents of this nature (dark night takoff) where the direct cause is unknown, ATSB usually mention the possibility of somosogravic illusion. It becomes a catch-all phrase. In this accident the pilot for some reason made an airborne report inside 20 seconds after lift off. That is poor airmanship and should have raised an ATSB eyebrow.
A black night takeoff on instruments demands the highest of instrument flying skills and sheer concentration. Talking on the radio at 100 feet off the ground was not a smart move. It would only take a few seconds after lift-off to relax one's grip on the control wheel and be slightly out of trim, to have a miniscule change of AH attitude either up or down. Old suction driven artificial horizons of that era had acceleration errors on takeoff causing erroneous attitude indications. Enough to be deadly at 100 ft AGL.in daylight, let alone at night.
The ATSB report mentioned VH-LKH was equipped with a Bendix M4D autopilot and flight director system. One avionics repair shop commented: "These and all attitude-based units from Bendix/King can be prone to gyro-induced flaws. Some possible symptoms of a gyro problem include shallow wing rocking and gentle pitch porpoising. The KI256 flight director gyro could be the problem."
In some ATSB reports we see reference to the pilots last instrument rating test and that nothing untoward was noticed by the Examiner. Well, a cynical view could be for obvious reasons of responsibility he would say that, wouldn't he?
One could speculate forever on this and similar night accidents where there was no obvious cause. The possibility of poor instrument flying ability at the time of the accident should not be ignored iin accidents of this nature.
Last edited by sheppey; 28th Jul 2020 at 05:53.