From a system design standpoint this discussion suggests the "A/c on ground" switch is such a critical component that it ought to have redundancy. Conceptually it would not be too difficult to implement either, as there are several other possible inputs besides the existing WoW switch. For example, airspeed below stall speed more than 1 minute, door open, engines off, or only slow movement in any direction detected by GPS. Granted, any single input may not give a bulletproof indication, but a simple computer program could presumably combine the inputs logically to give a highly reliable additional "on ground" indication. The question is, would the reduced risk be worth the implementation cost?