newt
Well Known Member
Interestingly, the language regarding the clock is even more specific that a digital representation is permissible.
The old (superseded) Australian CAO 20.18 specifications for required equipment for various classes of flight were less prescriptive than that: They required a "timepiece."
Which led to a memorable argument I had with someone at CASA after the Garmin G5 was introduced, about whether it was IFR legal.
CASA's position at the time was that any Experimental aircraft flying IFR could only be equipped with TSO instrumentation. Cheap knock-offs from Aircraft Spruce earned frowns, they really didn't want to consider approvals for anything that didn't have an FAA PMA number and a TSO compliance statement on it.
So Garmin brought out the G5. No TSO at all. Solid state gyros, color LCD screen. Exactly the kind of thing that sent CASA into a kermit-arms frenzy. Oh no no no, you can't use that for IFR, it isn't TSO.
So I asked them which IFR instruments didn't require a TSO. And they said, "they all need them."
So I pointed to the clause about the "timepiece" in CAO 20.18 and asked them if my wristwatch needed a TSO.
That led to a lot of incoherent harrumph noises, and a conclusion that all the IFR instrumentation in CAO 20.18 except the timepiece needed a TSO, even though the only parts of CAO 20.18 which mentioned TSOs were the parts applicable to transponders and GNSS navigators.
Anyway, it all finished abruptly as soon as Garmin/EAA brought out the STCs for the G5s, which meant IFR capable Cessna 172's could use them in accordance with their type certificate. It changed the argument from, "Why is this impossible?" to, "You've already approved it for the type certified aircraft by accepting the STC under your FAA equivalence rules, so why the heck can't the same instrument go in an RV?"
There was no reason for them to be obstructive, they just were. It's like the fable about the frog and the scorpion, "It's my nature."
- mark