Talk:Known Issues/@comment-5388427-20120809130306/@comment-5092393-20120810165100

The Garmin GLO looks like it uses the MFI frameworks. Apple mandates that GPS devices must deliver the data through the system, so that will almost definately work. External antennas, like the BadElf, work.

I'm not sure which "Garmin Pilot" you are refering to. The internal GPS on the iPhone isn't as accurate, especially for vertical speed, as other recievers. You can try to adjust the "Vario History" in the settings, which averages the values over several seconds. It's fairly hard to get proper vario information when the only data is 1m precision every 1s. As thermaling is almost per-second, you need much more accuracy than that, which requires a more accurate reciever that reports more often.

I have ordered the SerialIO device that other applications have used, and will be implementing connections to external GPS recievers, especially flight loggers like the Colibri and instruments like the Borgelt, which are designed specifically to get vertical speed.