I was watching that 717 flightdeck shot the other day when I realized that there was no basic mechanical instruments (Airspeed Indicator, Altimeter and Attitude Indicator) that could be used as a back up in case of electrical failure. I'm pretty sure that electrical systems are redundant and that you'd probably have better odds at winning the lotery rather than having a full blown electrical failure, but some people do win the loteries, and electrical failure happens.
So my question is, is there is mechanical instrumentation on the 717? If no what would one would do in case of an electrical failure on the 717 with IMC conditions?
Photo © Ben Wang