HondaJet: Not A Steam Gage In Sight

"Bucky" wrote in messageI found this article on the Airbus 320, which has
an all glass cockpit:

All glass, except the back-up altimeter and back-up airspeed indicator,
which are mechanical. The back-up attitude indicator has an internal battery
which is normally recharged by the aircraft's system. The FADECs are self
powered but the EICAS is not.

Many steam gauge airplanes will have indicator failures following the loss
of all electricity because the air reference instruments get data from an
air data computer and can't function in a stand-alone mode. Before RVSM ,
many airplanes had purely mechanical air reference instruments on the
co-pilot's side, but now most of those operate on a second air data
computer.

"The energy supply is backed up in several ways. Along with one
generator per engine, a third generator is powered by the APU. A fourth
power supply is available by extending a little fan generator into the
airstream. The chances of experiencing a complete power loss in an A320
are calculated to be at around one in one trillion.

And yet, it did happen recently. A loss of all display units has happened a
number of times.

Should this happen,
the above mentioned mechanical system of the rudder and the elevator
trim ensure a safe landing."

All well and good if one is in VMC conditions. Even then, the landing will
be 'eventful'. In the simulator, in VMC conditions, only 50% get on the
runway without damage and many of those don't stop on the runway. And good
luck finding an airport in the first place without the IRS, GPS, VOR, ADF,
or ATC.

D.