I’d download the simulators from both the Garmin GTN and the Avidyne IFD series and play with both of them. You’ll like either one or the other.
Should you keep your ADL, then I’d look at the compatibility between this and the IFD540. Gölze has a blog about this on his website (or was it Youtube?).
Why GNC355 and not GTN 650 + GMX200? if you go 650 route, you can remove one of the NAV/COM radios and get more space on the central console.
And you keep an upgrade path of replacing GMX200 with GTN 750 in the future.
The reason I was asking about Avidyne MFD databases is the old chestnut of the KMD550 not working fully with a Garmin navigator (something to do with the OBS mode; multiple posts but was never able to actually document it). I have 3 possible upgrade routes
Of course the old argument about MFDs being dead is well known, and most people go for two navigators. One old thread. But in general there is no need (is this right?) for the MFD to have a current database. Airports and mountains don’t move… So even if the database ends you probably have another 10-20 years.
arj1 wrote:
Where did you get 88 feet from?
PANS-OPS (6th ed.) volume ii. Specifically part 2, section 1, chapter 1.4.8.8 “Determination of OCA/H with OAS or basic ILS surfaces” and Table II-1-1-2 “Height loss/altimeter margin.”
The “height/loss altimeter margin” for approach category A aircraft is given as 42 feet with radio altimetry and 130 feet with barometric altimetry. From this you can deduce that the margin for pressure altimeter error is 88 feet.
The same criteria are specified for PAR and LPV approaches in different chapters.
Niner_Mike wrote:
So, what is the usefulness of a Radio Altimeter?
Maybe just cross-check on baro altimetry and terrain avoidance?
Obviously there is more than terrain bellow: obstacles, terrain profile, aircraft category, projected flight path many of these are done on baro altimeter
So radio altimeter will tell one they are about to hit terrain bellow without any sort of clearance assured, sort of warning to cross-check or get ready for impact !
But maybe worth gold for helicopters?
So, what is the usefulness of a Radio Altimeter?
How can you obtain a CAT2 license as a GA pilot in a GA machine (with Radio Altimeter)?
Airborne_Again wrote:
arj1 wrote: 250ft DH instead of 200ft for ILS approaches (50ft for barometer altimeter error).Do you mean the other way around? That you would have a 250 DH for ILS without radio altimeter and could use 200 ft if you had a radio altimeter?
Yes, sorry, meant another way around.
First, there is no need to increase the ILS CAT I DH to cater for altimeter error — that is already considered when the OCH is determined. (There is an 88 feet altimeter error margin — at least for approach category A aircraft.)
That’s what I’ve been taught here as part of IR(R)
Where did you get 88 feet from?
Also, you can’t simply use radio altimetry instead of barometric altimetry in a CAT I ILS as the terrain profile will affect the radio altitude. ILS CAT II approach plates have DH specifically given as radio altitude.
Thanks!
arj1 wrote:
250ft DH instead of 200ft for ILS approaches (50ft for barometer altimeter error).
Do you mean the other way around? That you would have a 250 DH for ILS without radio altimeter and could use 200 ft if you had a radio altimeter?
First, there is no need to increase the ILS CAT I DH to cater for altimeter error — that is already considered when the OCH is determined. (There is an 88 feet altimeter error margin — at least for approach category A aircraft.)
Also, you can’t simply use radio altimetry instead of barometric altimetry in a CAT I ILS as the terrain profile will affect the radio altitude. ILS CAT II approach plates have DH specifically given as radio altitude.
Don’t you need an operator in order to get permission for multi-pilot system in a light MEP?
