mixed airspeed instrument units, is this 'normal'

[exncsurfer]

A recent rental that I got checked out in had an add-on 'glass' pfd. I've used those before and they've always been matching to the airspeed units on the analog instrument and POH. This one has the electronic PFD in knots and the POH / analog airspeed indicator(which is still installed) is in mph. Just wondering, is that typical? If it was my plane I would want it to match. Maybe you get used to it, but it seems like it could add a small layer of confusion where it doesn't need to be. Thoughts? Is this a non-issue?

Thanks.

 

[Salty]

As an example, the STC for the G5 states it must be configured to the units in the POH. It might be "legal" (depending on the install) for a non-primary to be in different units, but IMO it's bad practice.

 

[luvflyin]

My thoughts are it could be an issue if the pilot is not use to it and might use the wrong airspeed in critical situations like when low and slow on approaches. And I think it is probably programmable in the PFD to display knots or mph.

 

[flyingron]

Well, it depends on the aircraft, but whatever the required paperwork/placards/markings are, it needs to be consistent. For example, the Navion owner's manual isn't a required doc, but the limitations book is. If you don't have MPH on your ASI, you'd need to update that document. Same for other units (notably temperatures).

I still get a chuckle over the antiquated term "True Indicated" in the book, however.