a) "Plane loses power" isn't that simple. There are multiple different independent "power" systems for different things, each with their own redundancies. Par

a) "Plane loses power" isn't that simple. There are multiple different independent "power" systems for different things, each with their own redundancies. Particularly critical systems, like engines, often don't need anything else in the aircraft to be functional to continue to work. Power failures, even fairly catastrophic ones, are trained for and there are checklists for such events. (This goes all the way to the point of losing power so badly that you have no instruments and no radios, there are procedures for using a very simple battery-powered radio transponder to alert ATC of this fact, who can flash high-powered light beacons at you to give you landing instructions when you get close.) b) Ignoring the "power failure" question, decompression at altitude is also a known danger with its own procedures. At FL350 (35,000 feet), you'd have 30 - 60 seconds of "useful consciousness"[1]. Aircrews can don oxygen masks in much less time than that; this is trained for. Further, continuous use of oxygen masks by at least one pilot is mandatory when flying over at an altitude greater than FL410 with multiple pilots, or above FL350 with a single pilot. Again, if things fail so catastrophically that aircraft-supplied oxygen doesn't work, there are small standalone oxygen tanks on hand to provide at least 10 minutes of air, which is more than enough time to make an emergency descent to a breathable altitude. Also, to the premise of the question, cabin pressure should never be lost in response to an electrical failure; these things are designed to fail "safe". There are mechanical components that have to be actively thrown for decompression, which can be done by hand if electricity is unavailable and won't be triggered during a loss of power. Uncontrolled decompression is usually the result of a structural failure (seal or gasket failure; metal structural failure; etc). [1] http://en.wikipedia.org/wiki/Time_of_useful_consciousness http://en.wikipedia.org/wiki/Time_of_useful_consciousness