iPhone6 Barometer

I am aware of those config options but I don’t think they completely block the telemetry.

They don’t. Application can access the network stack. Developers are bound by limitations and Apple reviews apps but that is just a cursory look and no guarantee at all. It’s only Apple that decides which privileges an app has, the user does not know it.

Whether Android is any better I have no idea.

It’s not and the application review is more automated and less strict than with Apple so the chances of something nasty making it to the app store are higher. However, there are two major advantages: first the user is told which privileges an application requests and can approve/deny. In reality applications tend to request a lot of privileges and users just confirm. More importantly, you can install a firewall on Android and control network permissions down to the last detail. Such things are not possible on iOS where Apple prevents apps like this from being installed.

Here is a precise step-by-step guide about how to stop your smartphone transmitting data (copyright Wall Street Journal)

How can you stop this from happening and protect your privacy?
Step 1: Turn off your smartphone.
Step 2: Throw it on the ground.
Step 3: Jump on it repeatedly.

I think that the only data that is transmitted automatically is location data – and only if you have “location services” set to ON.

(the best present-day solution would be a £5/month contract)

Actually I think the best present-day solution is a Three PAYG SIM which charges 1p/MB for data, which should work out cheaper than £5/month for a very occasional user.

Based on my bills, the lowest I see for data use is ~3MB/day. So this would be about 90p/month, plus whatever you actually used of course. Calls are 3p/minute and texts are 2p each.

Just read that Xavion now will use the iPhone6 barometer.

“We now use the iPhone6 barometric pressure sensor for altitude display if you have an iPhone6 or iPad with pressure sensor, and are NOT set up as a pressurized airplane in CONFIG:OPTION screen.

I have found from flight-test that the iPhone6 pressure sensor is more accurate in altitude than the GPS!"

http://xavion.com

I have found from flight-test that the iPhone6 pressure sensor is more accurate in altitude than the GPS!"

That’s surely impossible. You cannot get altitude from air pressure, unless you make big assumptions about the layer of air underneath you

• surface pressure
• the whole temperature profile, SFC all the way up to where you are

You can get the 1st one, sometimes, but you cannot get the 2nd one.

Barometric altimetry is fine for vertical traffic separation but it doesn’t give you an accurate altitude AMSL.

I hope you understood the statement was from Xavion :)

Not sure if the product really works, lots of enthusiastic claims and statements :)

Sure, you can build an accurate barometer (pressure sensor).

For low pressures (ambient air) they tend to be of this form

(that one is differential)

The resolution can be 16-bit and the accuracy… obviously not 16-bit but probably 0.5% (8 useful bits) is achievable, with temp compensation.

For low pressures (ambient air) they tend to be of this form

Good luck fitting this into an iPhone :)

I’m using this one, which is factory calibrated and generally within 80ft of the aircraft altimeters when fed with cabin air. Still doesn’t fit a mobile phone though :)