When the iPad was first released, the only way to use it with a bluetooth GPS appeared to involve jailbreaking and that wasn't something I was keen on doing. Ten months later there are at least two GPS devices for use with the iPad, both claim to be Apple-approved, and neither require jailbreaking. One is the Bad Elf GPS receiver and another is the GNS 5870. Both sell for around $100USD and both are said to work with the two electronic flight bag (EFB) apps that I use most often - ForeFlight Mobile HD (FFM) and Skycharts Pro (SCP). Saving my pennies and skipping soy lattes at Peet's Coffee finally paid off in the form of a new bluetooth GPS receiver for use with my non-3G iPad.
It should go without saying, but I'll say it anyway: The combination of any GPS receiver with an iPad or any other off-the-shelf computer hardware is no substitute for a TSO C125 or C145/146 IFR-certified GPS receiver. Anyone who claims otherwise needs professional help.
I decided against Bad Elf since it plugs into the iPad's 30-pin connector, a location that would seem to be a disadvantage in two respects. A small unit plugged into the iPad would seem to be susceptible damage for an iPad kneeboard arrangement. And with the iPad on one's lap or knee while seated in an aircraft, I can't imagine the Bad Elf is going to offer optimal GPS satellite reception. Siting outside, walking, or hiking, Bad Elf would probably perform just fine. Inside an aluminum, quasi-Faraday cage, not so much.
Satellites in Sight
The GNS 5870 is a small 32 channel bluetooth GPS receiver made by Global Navigation Systems GmbH. Physically it is a little bigger than a box of matches and weighs less than a set of car keys. Since it connects to the iPad via bluetooth, you can mount the receiver where satellite reception is likely to be best, such as near the windscreen. The unit is powered by a Li-Ion battery that is purported to last at least 10 hours. It comes with a mini-USB cable and USB cigarette power adapter. I wondered if routing the cable in an aircraft might be a bit of a challenge, but it turned out to be workable. The size of the cigarette adapter means it protrudes quite a bit, making Cessna's design decision to put the cabin power plug right above the fuel selector seem dubious, at best.
One issue some users have with the GNS 5870 has to do with the power switch, which is an unconventional touch sensor. Holding the unit with the display on on your left, turn it on by swiping your finger upward across the face of the display. To turn it off, swipe your finger downward. At first I had a bit of trouble turning the unit off, but discovered that a light touch and a relatively slow swiping motion was all that was required. It's easy to inadvertently turn the unit on and drain the battery, though I found a simple solution which I'll describe later. I'll second the observation others have made: A conventional power switch would have been a wiser choice, though not nearly as cool.
Once the unit is turned on, go to the iPad's Settings, ensure that bluetooth is enabled, and connect to the device. After putting my iPad to sleep during a fuel stop, I found that the bluetooth connection had been lost. I had to access the bluetooth Settings again to reconect the GNS 5870. This wasn't a repeatable problem. Hmm ... Otherwise, I found I could switch between apps on the iPad without disturbing the bluetooth connection.
There are several options for mounting the GNS 5870, but to avoid running afoul of FAA STC requirements you'll probably want something temporary like velcro. Since I fly in a variety of aircraft, my mounting solution is museum putty. Just a small bit of putty on the unit will temporarily and securely adhere it to most any surface. I used to recommend a putty product that Garmin marketed, but they seem to have discontinued it. No worries because the museum putty is less expensive that what Garmin used to sell - surprise!
To keep the putty from sticking to the inside of my flight bag, a wrapper of baking parchment (not to be confused with wax paper) works nicely. The putty doesn't stick to the parchment and it also acts as a wrapper that helps keep the device from being turned on by accident while it's stored in my flight bag.
Useful and Reasonably Accurate
I tried the GNS 5870 with both FFM and SCP with good results. Headed down SF Bay on a flight from Oakland to Monterey, the FFM display showed 10 meter accuracy and both apps displayed ground speed and current track readouts that closely or exactly matched the values shown on the G1000 multi-function display (MFD) and primary flight display (PFD).
In the examples below, we were being vectored and then were told to proceed direct KNUQ which is why the G1000 course line and the FFM course line are not coincident.
|G1000 MFD, Track Up|
|ForeFlight Mobile HD, North Up|
|Skycharts Pro, North Up|
|Skycharts Pro, Track Up|
The main advantage of the GNS 5870 is keeping your place on an en route chart displayed on an iPad. Neither FFM or SCP provide geo-referenced terminal procedures or airport diagrams, but both apps provide a subset of features you'd expect from a hand-held GPS receiver. SCP goes the extra mile and provides both desired track and current track as well as distance and time to the next waypoint. Neither app provides turn anticipation, a way to suspend waypoint sequencing, nor a way to define and display holding patterns.
Just as an experiment, I entered some of the waypoints that define the SCK RNAV (GPS) RWY 29R approach and found the GNS 5870's positional accuracy was quite good. The distance to the current waypoint actually matched the G1000 exactly, there was just a time lag between my taking the photo of the MFD and the iPad screen shot.
Both of these EFB apps display the GPS navigation data at the bottom of the iPad's screen and with the iPad in your lap you'll need to be vigilant about increased head-down time. Though the ground speed, track and GPS-derived altitude seem pretty accurate, I can't imagine using these displays to actually control an aircraft and I'm sure the developers (and their lawyers) would concur.
The GNS 5870 works well enough to make me consider trying one of the newer, lightweight RAM yoke mounts for the iPad to help ameliorate head-down tendencies. Guess I'll have to save more pennies and forego more soy lattes. The bottom line is that while this sort of GPS solution could help you avoid class bravo or visually acquire a unfamiliar airport, finding a runway at the end of an instrument approach is still the job for an IFR-certified GPS.