We had a few jet pilots report losing GPS data at high altitudes, and I was able to reproduce the issue on a Southwest flight over the holiday break. Kind of ironic, but it only shows up when you have a great WAAS lock! The MTK chipset starts spewing extra "metadata" about the signal strength, which increases the size of the data packets enough to confuse the iOS Core Location parser.
We're going to submit a trouble ticket to Apple, but in the meantime we've implemented a workaround in our accessory firmware that removes some useless leading zeros from the packets. No lost data, it just reduces the length of the packet enough to keep the parser happy.
The new Bad Elf GPS app showed up on the App Store this week. Follow these steps to update the firmware on your Bad Elf GPS:
As always, send any questions or issues to us at firstname.lastname@example.org.