"Isn't the O2 baro switch inhibited with gear on ground ??"
I think we would have to look at this on a case by case (airplane by airplane) basis, "GTT". For example, the 747-400 O2 automatic deployment system is based on a simple mechanical aneroid (no electrics). The system can be manually activated (via electrics) however if that fails. Having said this though, the movement of the aneroid (capsule), does complete electrical circuits for things like No Smoking signs, automatic PA announcements, etc. Once the system has been activated, the rush of pressurized oxygen into the distribution system unlatches the covers on the overhead mask stowage boxes and the masks fall down (another mechanical system with no option for an air-ground input).
I may be able to find further information on a variety of aircraft in our particular fleet, but none of these, as far as I know, is specifically designed for visiting La Paz. Now that I think about it, however, I would say that aircraft fitted with chemical O2 generators at each seat(which are activated electrically), would be better suited to landing at La Paz (as an air/ground input could easily be inserted into the activation circuit). Perhaps "aluminum ovcst" 's 737-200 had this type of O2 system?
Rgds.
Q.
[ 30 September 2001: Message edited by: QAVION ]