Question

Why are mechanical instruments retained when high tech LED displays are available?

(a) LED displays are costly

(b) LED Displays cannot withstand the flight environment conditions

(c) Probability of failure

(d) Accuracy

I have been asked this question by my college professor while I was bunking the class.

This question is from Head Down Display Technology topic in portion Displays and Man-Machine Interaction of Avionics

Answer 1

Right option is (c) Probability of failure

Easy explanation: Although high tech LED Displays are available the mechanical systems are still used as a fail-safe for the LED display. There is always a chance of electrical failure due to engine failure and power supply may be cut off. In situations like this mechanical systems are necessary to land the plane safely.