iPhone 6 to include a pressure sensor?

that would be interesting. I'd really like it on the iPad mini
 
NoHeat said:
I bet this could make some very nice aviation apps possible.
Click to expand...

Yes. There are a number of Android apps that use the pressure sensor (if available).

I think it's more useful for weather monitoring than altitude measurement, though. In practice, there's not much reason for your phone or tablet to use pressure altitude instead of GPS altitude (when I fly, my tablet is even using WAAS GPS).

You're not going to use your portable device for maintaining altitude or reporting altitude to ATC. If you're using it for stuff like tracking your flight path, then GPS altitude is fine.
 
Altitude alerter could be handy...
 
dans2992 said:
Altitude alerter could be handy...
Click to expand...
No reason the GPS can't support that without a pressure sensor. I really don't see much point in sensing ambient pressure, without a barometer setting the accuracy is on the order of +/- 1000 ft.

I suspect the reason this is being considered is that the MEMS gyro/accelerometer ICs are starting to come with magnetic and pressure sensors and the new devices are often less expensive than the ones they replace without those features.
 
gismo said:
No reason the GPS can't support that without a pressure sensor. I really don't see much point in sensing ambient pressure, without a barometer setting the accuracy is on the order of +/- 1000 ft.

I suspect the reason this is being considered is that the MEMS gyro/accelerometer ICs are starting to come with magnetic and pressure sensors and the new devices are often less expensive than the ones they replace without those features.
Click to expand...

Ok, but in order to be useful for ATC purposes (ie a reminder you are approaching your assigned altitude) the GPS only app would require the altimeter setting and temperature.

With a barometer, you'd only need an altimeter setting.
 
gismo said:
I really don't see much point in sensing ambient pressure, without a barometer setting the accuracy is on the order of +/- 1000 ft.
Click to expand...

If you've got internet access and you're reasonably close to an airport, then good data for an altimeter setting are available, right?
 
gismo said:
No reason the GPS can't support that without a pressure sensor. I really don't see much point in sensing ambient pressure, without a barometer setting the accuracy is on the order of +/- 1000 ft.

I suspect the reason this is being considered is that the MEMS gyro/accelerometer ICs are starting to come with magnetic and pressure sensors and the new devices are often less expensive than the ones they replace without those features.
Click to expand...
The way some of the apps work is they determine the QNH when you are stationary at the ground by comparing the known altitude at your GPS position with the pressure reading from the barometer. Assuming you don't stray too far, they can then use that setting to fairly accurately determine your altitude.
 
dans2992 said:
Ok, but in order to be useful for ATC purposes (ie a reminder you are approaching your assigned altitude) the GPS only app would require the altimeter setting and temperature.

With a barometer, you'd only need an altimeter setting.
Click to expand...

In order to use that altimeter with ATC, wouldn't it need to pass an altimeter check? Would it need a TSO?:dunno:
 
The pressure sensor doesn't need an altimeter setting. That's pure software.
 
dans2992 said:
Ok, but in order to be useful for ATC purposes (ie a reminder you are approaching your assigned altitude) the GPS only app would require the altimeter setting and temperature.

With a barometer, you'd only need an altimeter setting.
Click to expand...

Why get so fancy? Use the GPS altitude, and set your alert for 500 or 750 ft before your target. The accuracy is perfectly good enough.
 
JeffDG said:
The pressure sensor doesn't need an altimeter setting. That's pure software.
Click to expand...

I don't know what you mean. If you want to turn the pressure reading into an altitude that matches your altimeter and ATC's expectations, then you would need an altimeter setting. If you had a good data connection, then you could cleverly grab that setting via the Interwebz, but you still need it.
 
Henning said:
In order to use that altimeter with ATC, wouldn't it need to pass an altimeter check? Would it need a TSO?:dunno:
Click to expand...


Was talking about using it as a "backup/situational awareness tool" not as a primary flight instrument.
 
Jim_R said:
I don't know what you mean. If you want to turn the pressure reading into an altitude that matches your altimeter and ATC's expectations, then you would need an altimeter setting. If you had a good data connection, then you could cleverly grab that setting via the Interwebz, but you still need it.
Click to expand...

But that "altimeter setting" has nothing to do with the pressure sensor.

If I have a pressure sensor that tells me that I have 30.17" Hg, then in software (the app itself), I can accept a user-entered altimeter setting and convert it to an altitude via pretty easily computed formulae. That's a function of the application, and does not require anything hardware wise.
 
Even if you could enter an altimeter setting, a barometer on an iphone wouldn't be accurate. It would read higher than actual and that difference would vary with speed.

Unless you want to plumb it to a static port.
 
I can tell you one potential use of a pressure sensor, and it isn't even aviation related. GPS elevations are normally accurate to within a few feet, making absolute elevations accurate for any practical purpose. But cumulative elevation gains and losses, if you track them, are wildly inaccurate since the errors are magnified.

Some of the GPS bicycle computers are equipped with pressure sensors for that reason.
 
dell30rb said:
Even if you could enter an altimeter setting, a barometer on an iphone wouldn't be accurate. It would read higher than actual and that difference would vary with speed.



Unless you want to plumb it to a static port.
Click to expand...


I think the error is only on the order of 20-50 ft though. Some planes have alt static sources in the cabin.

Better than the 6-800 ft the GPS altitude often differs by.
 
Lindberg said:
The way some of the apps work is they determine the QNH when you are stationary at the ground by comparing the known altitude at your GPS position with the pressure reading from the barometer. Assuming you don't stray too far, they can then use that setting to fairly accurately determine your altitude.
Click to expand...
I've had several watches with this ability and never found a useful purpose, especially WRT flying. Worse yet the watches had no way to input an altimeter setting for the altimeter. Hopefully the new phones will address that shortcoming so you could use one as an emergency altimeter but if I lost my altimeter in flight, I'd rather rely on GPS altitude since that will keep you out of the rocks and trees.
 
gismo said:
I've had several watches with this ability and never found a useful purpose, especially WRT flying. Worse yet the watches had no way to input an altimeter setting for the altimeter. Hopefully the new phones will address that shortcoming so you could use one as an emergency altimeter but if I lost my altimeter in flight, I'd rather rely on GPS altitude since that will keep you out of the rocks and trees.
Click to expand...
That's entirely app dependent. There is an android app called "sensitive altimeter" that will find the altimeter setting for the nearest airport or let you enter manually.
 
If you want to trust GPS altitude, a barometric pressure sensor could actually calculate an altimeter setting.

There are 3 variables in the equation: True Altitude, Pressure, and Altimeter. If you know 2, you can calculate the third.
 
I will buy one when they put a damn back button on their stuff.
 
FWIW pressure sensors are not new. Messaging to read that pressure in the cellular system, calibrate it to get an elevation is however. Part of the reason for these pressure sensors is an on going NPRM from the FCC and other regulatory groups to improve location technology such that we can pinpoint on what floor of a building you are on.

Get excited all you want about the pressure sensor. The main reason is to track users better. Think about that!

BTW feel free to comment on the FCC NPRM too. http://apps.fcc.gov/ecfs/proceeding/view?z=2vrcu&name=07-114
 
Last edited:
SixPapaCharlie said:
I will buy one when they put a damn back button on their stuff.
Click to expand...

Swipe right or left for back or forward is an elegant way to eliminate a physical button.

But I still feel getting rid of the dial was a mistake:

ma-bell-iphone-131004.jpg
 
on my android, I click back and it takes me back to what I was doing before be it a different page, app, etc. It is intuitive and makes sense.

It is also located at the bottom of the phone where I keep my thumbs.

I have an iPad for flying, and I had an iPhone for a week and I had a Mac mini for two months. I can't wrap my head around how they do things.

I remember my first encounter with a Mac. I asked my friend where the eject button was on the CD ROM. He said just drag the CD drive Icon to the trash bin to eject.

Without having been given that instruction there is no way in a million years I would have come to a logical conclusion that dragging an icon to the trash would open the CD door.

A lot of their stuff is weird like that.
 
JeffDG said:
If you want to trust GPS altitude, a barometric pressure sensor could actually calculate an altimeter setting.

There are 3 variables in the equation: True Altitude, Pressure, and Altimeter. If you know 2, you can calculate the third.
Click to expand...
You don't have to trust GPS altitude, which is less precise horizontal position. If you know when you are the ground, you can turn the position into an altitude using USGS or other map data and then that to adjust altimeter. I think at least XCsoar works that way.
 
You must log in or register to reply here.
Back
Top