Sunday, February 13, 2011

GNS 5870 Bluetooth GPS for iPad

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.

Developing Attachments

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 offers the ability to display either North Up or Track Up and also provides the distance and bearing to the airport nearest to your current position, though bigger numbers would be easier on my aging eyes.

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.


privatepilotlog said...

Awesome post - I am looking into getting an external GPS for my ipad...but I was leaning towards the Badelf (with an extender cable in order to put it on the wind screen). The only reason for this is because of the WAAS capability of the bad elf. What are your thoughts on this? Does the GNS get accurate reception? Granted my flying is VFR only.
Check out my blog:

John Ewing said...

Perhaps my writing style is overly complicated, but if you re-read what I wrote you'll see that I found the groundspeed, track and altitude displays on the iPad with the GNS 5870 all matched what the G1000 was displaying. I've yet to lose satellite reception with the GNS 5870, but I haven't been using it that long.

In my opinion the BadElf may have the advantage of WAAS, but even with a 30-pin extender cable the possibility of damage to the iPad or the BadElf unit itself outweighs any additional GPS accuracy it may offer. The advantages of a wireless, bluetooth connection between the GNS receiver and the iPad is a huge advantage. Others may come to a different conclusion.

JetAviator7 said...

I haven't gotten an iPad yet, but hope to get one soon. It is amazing to me all of the technology that is becoming available to us as we fly.

Seems the days of the white scarf and aviator goggles are now long gone!

Chad said...

Great post...I'm 99% sure this is the receiver I need, pending one question I haven't seen addressed anywhere. In my case of a corporate jet cockpit, I am flying with two iPad's equipped with ForeFlight. I'm wondering if the GNS 5870 can talk to two iPads at the same time.

John Ewing said...


No, I do not know of a way to have the GNS 5870 talk via multicast to multiple devices. I understand work is being done on a bluetooth multicast protocol, but it ain't there yet for the iPad and the GNS 5870.

Creamy said...

Thank you for the post. I just got my GNS but have been running the iPad using the 3G GPS position. However, in the cockpit of a 30 series Learjet, very little signal can get through. Handheld GPS, Sat phones, and XM weather receivers all fail. So the GNS is my solution. I will put it in the back of the plane, connected to one of the AC outlets, next to a window. When the plane is powered up, it will come on automatically allowing the iPad to pair with it. Once the iPad is taken away and it loses it's pairing, it will auto-shutoff.
Also, as an update, Foreflight Mobile HD now offers georeferenced approach charts, and most importantly, taxi diagrams. Not sure about Sky Charts.
Now if we could just find a way to display XM weather on our iPad, all would be good!

Alexander said...

Hi, thought I might mention the GNS 5870 is WAAS and EGNOS enabled.

Ettinger said...

I have the GNS 5870 and an ipad 2 and it is not discoverable. Any advice. My ipad does find a bluetooth keyboard, but not the GPS.

John Ewing said...


First, take a paperclip and press the reset button (small hole on the edge of the device near the end with the USB connection). After resetting, try pairing again.

If that doesn't work, you may find an answer on one of these links:

If that doesn't work, email me and I may be able to offer more assistance.


Dion said...

Hello. I have had three of the gns 5870 units. The problem with the first was it would not stay connected to bluetooth in my airplane or my car. It would connect then disconnect then reconnect ect... About 30 seconds on and 30 seconds off. Sent that one back and reordered another one. That one stayed connected to bluetooth in my airplane and car but the unit would not turn off. I know there was a problem with that with the early ones. Sent that one back and ordered another one from a different company. Same as the first. Will not stay connected to bluetooth. On for 20 seconds off for 30-40 seconds. Any advise. Would think that my ipad(1) is the problem but the second unit that I got had no bluetooht connection problem. Thanks for any help!!

John Ewing said...


Well I'm obviously not tech support for GNS, but here are some things that come to mind:

1) See if the GNS 5870 will stay connected in a "sterile" environment - no cell phones or radios that might be generating RF interference.

2) Try using the GNS 5870 with someone else's iPad or another computer with bluetooth. That may help you determine if the problem is with you iPad.

Good luck,


Pablo said...

Great post! I also had a question on the gns 5870. When I first got it, I downloaded the fore flight app to verify functionality of the moving map and it worked great with trial version. Of course after reading the reviews on wingX pro I wanted to try it. I also downloaded the app in the trial version but immediately noticed that it did not seem to be communicating with the gns5870. I kept receiving messages on the moving map claiming no GPS. I did check the BT connection on the iPad settings and it was connected to the gns5870. Also the BT and GPS lights on the 5870 where solid, meaning connection and GPS were being received. I could not find any settings in wingX app to try and connect to the external gps. Could this be an issue related to the trial version of the app? Has anyone experienced this? I tried contacting wingX support but no response. I am leaning toward buying the wingX app because of all the great features, but I would like to know that it's gonna work with the gns5870 before I fork over $99 for a subscription.

Nino Desposati said...

I purchased a GNS 5870 Bluetooth GPS for my IPAD. Connects fine to my IPAD (3G Unit) but I’m not sure which GPS it using the built in IPAD GPS or the GNS 5870. Some areas in the cockpit I received no fix , yet my GNS 5870 shows full green gps signal. Is there a way to disarm the build gps receiver in the IPAD?

John Ewing said...


Can't help you with regard to WingX. I reviewed the iPhone version of that product, but my attempts to obtain the iPad version were unsuccessful. Like you, I couldn't get a response.


John Ewing said...


I don't have a 3G iPad, but suspect that your question could be answered be either Apple or tech support for the product you're using. You might check the ForeFlight support forum.


JohnH said...

I bought the ipad 2 3g and the elf. The internal gps showed 5m / 16 ft accuraqcy most all the time with several aviation apps. (Foreflight, WingX) That was very good. The elf always showed 10m / 32 ft. That seemed odd with WAAS. I emailed elf. They responded very quickly and said the elf is 2.5m accuracy capable but apple ios will only report 10m at best. They have in-house tested their elf and stand by their results wholeheartedly. I picked the elf with extension cord due to WAAS capability and power or connectivity is never an issue. One cord.

BlueSkyFlyer said...

Thanks for the terrific post. Was wondering. Why is it that the FAA doesn't acknowledge these bluetooth receivers for use by aircraft operators like mine, a Part 135 Operator.

captainharisd said...

would the GNS 5870 work inside the cockpit of a commercial airliner? i presently fly the A320 and its very difficult to get any GPS signal for any device. would appreciate any feedback so that i can buy this reciever.

John Ewing said...


No idea if the GNS 5780 will work inside the cockpit of an A320. Don't see why it wouldn't, but I have no empirical evidence to back that up.

Tony said...

In response to the user who has the 3G and the GNS bluetooth GPS and was wondering which was being used... I'm in the same boat (plane?) and found the way to force the issue was to put the iPad into Flight Mode.

Then I turned back on Bluetooth and WiFi. I could then use the Internet via WiFi (yes, a bunch of limitations there I know, but up in the air it doesn't seem so bad).

You could also pair with an iPhone if you need that connectivity.

Hope that helps