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Reducing GPS database costs

At one end of the spectrum, a lot of people fly with their panel mount GPS databases years out of date.

At the other end, people pay for the 13 cycle AIRAC updates which, for the KLN94 for example, comes to $410/year.

Clearly a lot of people are not flying "Eurocontrol IFR" and do not need the very latest database.

A good system of reducing database costs would be for someone who pays for the full 13 cycles to pass their just-expired flash cartridge down to somebody who is happy to fly with a database just 1 cycle out of date. It's a lot better than flying with a database that's a year out of date!

If the recipient paid half price for that, he would get the update for half of 410/13 i.e. $16 i.e. £10. That is really cheap!

The catch is that the flash cartridges are expensive. They carry the "secret" database key. The recipient needs to give the donor his old cartridge, so it can be re-used. So the scheme is not likely to work by mail, because some people will not return their old ones.

Administrator
Shoreham EGKA, United Kingdom

Won't work on GTNs as the cards are encoded to the actual unit. Does it work in 430ws?

EGTK Oxford

The 430/530 units use the same "branding" technique for the database. In addition you can only download them once to a card.

It's probably not overly difficult to break that mechanism and maybe it has been done.

I once flew IFR to Paris just after they had completely reorganized their airspace, waypoints and arrivals with an outdated database on the 430. I sweated more than on any other flight, trying everything to cover up the fact and not admit over the radio that I didn't have the right database. French ATC were mean and didn't want to provide vectors just waypoints that I didn't have

Won't work on GTNs as the cards are encoded to the actual unit

How does that work?

The database key has to be stored "securely" somewhere.

It can be stored on the card itself (Honeywell, Garmin GNS) in which case the card cannot be duplicated, for obvious reasons.

Or it can be stored in the GPS box, in which case the card should be copy-able freely but the database on the card will be key-ed to the key in the GPS.

It's probably not overly difficult to break that mechanism and maybe it has been done.

I am (really) not aware of any hack which would allow the database card to be copied. Also the KLN94 card is a 48MB Sandisk CF card which is itself very unusual.

Administrator
Shoreham EGKA, United Kingdom

How does that work?

When you setup your account for the database download, you have to provide the serial number of your GNS/GTN and it is then part of what gets stored on the card. The device will only accept databases that were written for its serial number.

What makes it more difficult is that they use special memory cards with their own reader so you can't just mount it as a drive and inspect/modify the files.

OK, they seem to have gone for a double-keyed system for the GTN.

What a hassle! I wonder why they did that. It means that if e.g. you have two planes, you need to pay for two databases even though you fly only one at a time.

All the older cards can be swapped around freely from one GPS to another (of the same type), and my proposed cost sharing scheme would rely on that.

Administrator
Shoreham EGKA, United Kingdom

What makes it more difficult is that they use special memory cards with their own reader so you can't just mount it as a drive and inspect/modify the files.

Not for the GTNs. They use normal SD Cards and readers.

EGTK Oxford

The GNS database cards can be used in any unit. I have even loaned my database out for a student that did not have a current database so they could take a check ride. For some owners that have dual GNS units such as a GNS530 and a GNS430 will only do a single subscription. They move the expired database to the 430 and reprogram the 530. The cross fill function won't work, but many pilots don't care as the 430 is only used for backup and is usually set to continuously display the traffic page if they have a TCAD installed.

For those that have a Honeywell subscription, they update the database via the internet and they get 13 updates for an annual subscription. There is also a 7 update option that is less expensive, but is only available every 56 days. One of the nice things that Honeywell does is permit the pilot to download the subscription over an 18 month period, so if they happen to not fly during a month, they just skip the update and use it later.

I am also unsure about the GTN database limitation as Garmin offers a bundle for all their databases to be used on the same aircraft. So if you happen to have dual G600's, a GTN750, and a GTN650 installed in the same aircraft, you can load all of the units with the same databases. I haven't actually done this, but I would hope it wouldn't require 4 database downloads as this would be very inefficient.

KUZA, United States

The GTN database remains on the card I believe so yes, you would need 4 cards downloaded and updated in JSUM to use 4 GTN systems. I have dual 650s and have to program 2 cards.

EGTK Oxford

Not for the GTNs. They use normal SD Cards and readers.

OK; that is a user-friendly move (the $200 flash cards were a hassle; it took me a while to get my hands on 3 of them so I could rotate them, with 1 spare) but Garmin had to somehow lock the database to the GPS - they probably encrypt the database using the GPS S/N as the key.

One of the nice things that Honeywell does is permit the pilot to download the subscription over an 18 month period, so if they happen to not fly during a month, they just skip the update and use it later.

Yes; I do that all the time. Skip cycles in the winter if not doing Eurocontrol IFR flights for 30 days. Unfortunately, funny you mention that, today I have realised I pushed this a bit too far and I won't use up all 13 cycles in the 18 month period. 2 cycles (worth $63) are going to be wasted

I have dual 650s and have to program 2 cards.

How much do you pay for the two?

Administrator
Shoreham EGKA, United Kingdom
72 Posts
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