Avionics that become completely useless, and database-induced obsolescence

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)?

RADALT.

CAT2 for private ops is hard. Many years ago I knew a pilot, twin TP Commander, who got CAT2 approval. He loved complying with complicated regs; it was a personal challenge. Then he packed it all up and bought a boat

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?

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.

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

• 2 × IFD540
• GTN650+750
• GNC355 and replacing the KMD550 with a compatible MFD

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.

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.

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?).