IFR GPS as clock for ifr flight

[JimNtexas]

I contend that the clock in our Cardinal's IFR approved KLN-89b GPS constitutes a legal digital clock as required for IFR flight.

My partner says, no, its a gps, not a clock.

I say, "Gps is based on time, it's IFR approved, it shows the time to a gnat's a**. Of course it is a clock".

Which of us is correct?

 

[vossdr1]

If you get a RAIM flag, does the clock still function properly?

Does it display minutes and seconds?

If yes to both of the above, I'd use it. Perhaps you should call OkCity and see what they say.

 

[mike1mc]

I think that would only be legal if you had an MEL for the aircraft that stated the GPS could be used if the clock becomes inop. It obviously wouldn't be a permanant thing however.

 

[100LL... Again!]

Why not? Digital clocks are allowed, and seconds function is provided, right?

That's a clock.

 

[Bandit60]

Can you have a MEL in a single engine?

 

[PropsForward]

Yes, if it GPS displays the time in including seconds. and the time is not dependant on signal from the satelites, then you are good to go.

I have flown aircraft that has a clock built in to the ADF radio. Works great and legal.

 

[satpak77]

keep it simple

the box is "IFR Approved right?"

that means everything in the box is approved, RAIM being available. Note the AIM and various AC's discussed RAIM availability as being necessary for IFR flight.

Our bureaucratic FAA is not going to approve "IFR Legal" but with a smaller sticker "well, the clock is VFR only"

dont get wrapped around the axle on these things

"IFR Approved" -----> means its IFR approved

my IFR approved clock is a $29.99 Timex on my wrist. It does not need RAIM and if I switch airplanes I don't need differences training

by the way, all the GPS's I have used got UTC TIME off the satellite (its a GPS), but the "stop watch" or similar function were likely some internal software or card that counted down, but I could be wrong on that.

 

[TonyC]

It seems this (or a very similar) topic was discussed earlier:

IFR equipment question


I'm not entirely certain what the bottom line was, but there were several opinions offered.

 

[JimNtexas]

the box is "IFR Approved right?"

that means everything in the box is approved, RAIM being available. Note the AIM and various AC's discussed RAIM availability as being necessary for IFR flight.

...

I agree with one quibble. RAIM is only required to fly a GPS approach. RAIM is n/a in cruise flight, and many GPS units that are approved for enroute and terminal only don't use the RAIM feature at all.

RAIM performs a computation that predicts the number and geometry of satellites available at the time the box expects to fly the approach.

You only need one satellite to know what time it is, and even before you acquire the first satellite the box likes to know the time so it can compute which satellites to look for, rather than doing a whole sky search.

Everyone who stayed awake in their celestial navigation class should know that. That is why the gps internal clock is always running even when the unit is off.

The bottom line is that the gps is built around an accurate digital clock. I would maintain that any gps unit that is panel mounted is a legal clock for ifr flight, even if it is placarded as vfr only.

 

[JediNein]

The Aircraft Electronics Association has posed that question to the FAA's airworthiness people. When they come back with an answer, I'll post it here.

Fly SAFE!
Jedi Nein