Incremental Data Downloads

Ever since FlyQ EFB 1.0, FlyQ has done what we call “incremental downloads.”  That means that we only download new charts and maps that have actually changed each cycle, not charts and maps that have not changed.  That means that your first download takes a bit but subsequent downloads are very quick.

As an example, the FAA has about 17,000 approach plates, SIDs/STARs, MINs, and airport diagrams in their system.  Every 56 days they do what they call a “Book Cycle” (as in they publish a printed book) where about 10-20% of those documents change.  On the in-between 28 day cycle, only about 2 or 3% change.  When you download data from the ChartData Manager in FlyQ EFB, we know which plates have changed and download just those.  That saves a tremendous amount of time downloading the plates.

Similarly, although the FAA updates all IFR enroute charts every 56 days, the Sectionals, TACs, and WACs are updated either every six months or once a year and not all at once but in groups around the country.  Although the FAA does not provide Sectionals by state, we compute which states contain any part of a Sectionals/TAC/WAC that has changed.  We use that data to smartly download only the Sectionals for states that have any changes, not all states.  As Sectionals are large, this is a huge time savings.

Finally a note about the expiration date of the plates and airport diagrams:  If you’re checking for valid dates of the plate by looking at the side of the plate, you’re being misled. The FAA prints two dates on the side of each plate. Although they look like expiration dates, they are not. They simply represent the print cycle of when that plate was last printed by the FAA. That is, even if a plate doesn’t change for two years, every 28 days, it will have a new set of dates on the side. FlyQ ignores these dates and uses a database that the FAA publishes to download only the plates that really have changed or been added. Thus, even when all your plates are current, you may see ‘old’ dates on the side. You have to keep in mind that, unlike IFR enroute charts or Sectionals, there is no planned expiration date for a plate — they just update it when necessary. Thus, it’s not possible for them to print an expire date on the plate since they have no idea when it might expire.

Plates do have revision info on them in the lower left corner, however. This revision info remains constant even when the date on the side changes (unless the plate really was changed, of course) but it’s hard to decode as it sometimes involves what’s called a Julian date. Moreover, unless you know for sure what the “current” revision info is, it doesn’t help you much as there is nothing to compare it to. We all just have to rely on the FAA accurately marking plates when changed. The good news is that we’ve been doing this for 10 years and I’ve NEVER seen them make a mistake about this.

Finally, in the ChartData Manager, you can tell FlyQ EFB to download ALL plates, even the ones that have not changed.


5 thoughts on “Incremental Data Downloads

    • Release dates are based on product quality. We’re working feverishly to get 2.0 ready for the public but it’s not quite there yet. We’ll be releasing a beta version soon to our testers. Then it’s a matter of what bugs the beta testers find and what bugs we find internally.

      Thanks, Steve


  1. How about a fix for the bluetooth issue, since apple is now talking about end of June release. I read that you are working on a work around fix. I really think that would be a priority at this time.



    • Good point. But it’s not quite that easy. Remember, it’s an Apple bug. We have implemented a workaround for the Dual XGPS 150/160 GPS receivers and the Dual XGPS 170 ADS-B receiver for FlyQ EFB 2.0. But it’s specific to those devices so it won’t help if you have a Bad Elf. This is why we and every other vendor relied on Apple’s built-in system for sending data from external GPS units to apps — it should have been more reliable and more generic than relying on vendor-specific code. Obviously that wasn’t the case here.

      That said, we have reason to believe that Apple’s iOS 8.4, which we have confirmed properly fixes their bug, will be released before FlyQ EFB 2.0 so the issue will be moot.

      Thanks, Steve


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