Originally Posted by CRM114

Pumps don't move the fuel as much as they attract the fuel. Like a magnet, the pumps can attract of repel fuel. When in 'ionic mode A" the chemical ionic bonds are bias to draw fuel toward them. In "ionic mode B" the pump polarity is reversed and the electrochemical magnetic dissonance can keep the fuel in it's place. The bypass pipes are wrapped in biasing coils to provide mode A or mode B attraction or repulsion. In ground school, they teach as "fuel come here" or "fuel - stay!"



The RNAV unit figures out where it is, by calculating where is not. In approach mode, the time delay on the GPS only allows the aircraft to calculate where it was which is subtracted from the IRS flight plan of where it wants to go (where it was - where it wants to go). Based on the implied position, the glideslope is determined. It's all self contained so that LOC and GS are supplementary.





It sometimes will, but not always. See above.



The Airbus uses Wink/Blink mode. When ditching, one inlet and outflow valve close (wink mode) and the other modulates to maintain a breathable level. If the level isn't good enough, the other inlet, and possibly the other outflow valve can close (blink mode) until the air is OK at which time the system reverts to wink mode (it never is stuck with "last air"). Upon touchdown in ditching command, the aircraft will automatically go to sink mode until the proper differential pressure is achieved.



The A330 altimetry is a tricky beast. Maybe an Airbus guy can clarify.