I don’t think it is anything modern like ARINC429. It’s a simple serial stream (clock and data) that goes to a KDI572. In fact (without looking in the IM) it could just be RS232.
BTW I think the need for a GPS for initial location could be eliminated, aiding a bit in simplifying the thing and perhaps a bit more in getting it certified. And to offer any added value, GPS-independency is a first requirement.
How would you get the initial position?
Actually there is a way to do this with just one DME station, and doing what they do to position geostationary satellites in orbit (lots of distance readings and you solve the simultaneous equations to get the 3D trajectory). I was in a Concorde cockpit (after landing, on one of its last flights) and the guy told me that’s what they use. INS with a single DME.
Also would you really go flying if GPS was not working? I wouldn’t, except on a trivial local flight in CAVOK conditions. Obviously a lot depends on why GPS is not working 
In most FMS systems they have DME sets which can work multiple channels. On the Proline 21 aircraft I fly the FMS3000 accept inputs from a DME 4000 which can simultaneously interrogate 3 DME stations, in addition to the 2 NAV receivers and the GPS4000S
In Australia the ADF is useful for listening to the cricket when flying in the outback….
In Australia the ADF is useful for listening to the cricket when flying in the outback….
As I have said before. On my PPL test the examiner tuned it to ABC radio national and fell asleep. And I mean properly asleep.
Does any European country allow it, in the sense of being able to fly an NDB or VOR approach using an IFR GPS?
I know airlines are allowed to do this, using their FMS (INS based). They have some rules e.g. the navaid must be operational.
Peter wrote:
Does any European country allow it, in the sense of being able to fly an NDB or VOR approach using an IFR GPS?I know airlines are allowed to do this, using their FMS (INS based). They have some rules e.g. the navaid must be operational.
AFAIK every country allows it as long as you monitor the navaid and take action if the indications show you are not flying the approach correctly. How can they they not? If you monitor the navaid and the indications are correct, you are flying the NDB or VOR approach.
My examiner let me do it on the IFR checkride. I had to fly a NDB approach to rwy 25 at EDMA and of course I put in the AGB NDG as a DCT in the GPS.
I flew it just the same then and and told the examiner what i did (“bearing becoming smaller, steering to the left ….”) .. but i looked at the GPS bearing and not the needle. He told me later that this was the right way to do it, if i also checked the needle “every now and then” …
I meant without carrying the navaid receiver.
The USA allows it in some circumstances.
Fior sure they allow the substitution of DME by GPS …
