Garmin Terrain Database

How often SHOULD it be done?

Last time the Alps folded was about 30 million years ago.

AFAIK pretty much all of these terrain datasets are derived from the Shuttle Radar Topography Mission that flew in 2000.

So I see very little point other than helping Garmin’s bottom line in updating the terrain DB.

There is however some aspect of this: the terrain warnings are suppressed in the proximity of known airports.

Garmin don’t want to discuss what they do and it is undocumented.

In some cases the warnings are bogus e.g. I got one doing the ILS into St Gallen and there was nothing anywhere near on that track. But the system seems very reliable where there are obstacles.

So it is conceivable that some corrections may be made to the data, over time.

But I agree with Tom and wouldn’t spend money on it. I have not updated my “Garmin 496 GPWS” since I got in c. 2005.

This requires that the latest version of software available is loaded.

Read your AFM very thoroughly. Normally, you need only a current aviation database if you want to fly RNAV approaches. Note aviation database. The terrain feature is not certified, and therefore there’s no regulation on the terrain database age, or that the terrain database even must be present.

Also, for BRNAV only, you do not even need a current database, you could use an outdated database where you checked every point you need against the AIP (not very practical, but at least allows you to legally continue to fly without switching databases if your flight happens to cross an AIRAC cycle boundary )

There are 2 sets of card readers.
One is the Jeppesen Skybound USB G2 translucent blue: This is used to update the aviation database
The other ist the Garmin USB card reader in black with a cable: This is used to update terrain cards and flight plan cards.

I have both, but never bothered to update the terrain card.

Where are you based?

Maybe more important than the terrain update is to update the obstacle Database ? this obstacle DB is also loaded on the terrain datacard.
And to update the terrain/obstacle datacard, you need that “special” garmin card reader (as mdoerr wrote), Garmin cannot deliver those card readers in EU (something with environment and disposal , but there are other ways to get them) several Garmin dealers have one.

The Terrain Feature in the GNS430W is not required to be current for any IFR operation, including RNAV approaches. You don’t even need to have the terrain card inserted in the unit. It is a different card part number than the one that is use to store the aviation data and the two are not compatible with each other. If I recall the terrain datacard is 256 MB and the aviation datacard is 16 MB. The terrain datacard stores two databases, the terrain database and the obstacle database. The terrain database does not have a regular update cycle. I guess if a volcano blows its top, an update may end up being made available. The obstacle database is regularly updated, I think on a 56 day basis. I personally update mine roughly once per year although one can purchase an annual subscription. Garmin has a separate programmer for the Terrain and obstacle databases and it is relatively expensive, about $200 US.