i noticed after flying yesterday that i was hovering around 2 feet off the ground and it was saying that i was 12 feet.  this has happened to me a couple of times before even after i have calibrated.    is this just an anomoly or should i be concerned?

Did you take off from a different point? If so, the altitude is measured from your point of take off.

I mean when I was coming back in to land it said I was 12 feet when I was only  a few feet off the ground.    its done this to me in past

tommycbaker@swb Posted at 2015-9-20 09:32
I mean when I was coming back in to land it said I was 12 feet when I was only  a few feet off the g ...

I am seeing something similar.  I took of and went up to 35' went 1000' south came back to me and it seemed lower even thought it said 35'  then I took it straight back south again 1000' and when I got there I was within a few feet of the ground so I went up to 85' and flew back to me and landed and it gave me a reading at landing of 29.6' when it should theoretically be zero (I was hoping it would be better than this).

Sir Edward K Posted at 2015-9-21 16:58
I am seeing something similar.  I took of and went up to 35' went 1000' south came back to me and  ...

Altitude is a barometric pressure reading.  If the baro pressure was changing dramatically it may cause this... Just an idea.  But in theory it is possible.

jaronpv@hotmail Posted at 2015-9-22 16:14
Altitude is a barometric pressure reading.  If the baro pressure was changing dramatically it may  ...

No not in this case.  Very calm stable weather conditions and was the very best day for flying yet for me 3 MPH wind perfect blue sky and 73 degrees.  

Sir Edward K Posted at 2015-9-22 15:54
No not in this case.  Very calm stable weather conditions and was the very best day for flying yet ...

Hmm. interesting!  I have had variances of a couple feet.  I think the most I have seen is 10 feet.  But I am not always paying attention to that.  I'll pay more attention now that you have pointed it out!

I have encountered this issue twice already. During auto take off it was ok, hovering about 4 feet. When it was time to change battery, while trying to land the bird I noticed the height indicated 2 about feet but the bird was at about 5 feet. Then when it's near the ground the display indicated negative 2 feet. I did a gimbal calibration & everything was fine after that.   

my new p3p shows the same thing...

as soon as i startup it shows -0.8 m. leave  it for a few seconds it goes up to -0.2m..
however,  landing after a 15 mins flight the altimeter shows 18 meters ..

i hope there is a fix for this..

walid666 Posted at 2015-9-22 17:25
my new p3p shows the same thing...

as soon as i startup it shows -0.8 m. leave  it for a few second ...

Happened to me after up grade to ios9

This may have been the cause of a crash I had a couple of days ago. I took off, went about 80 feet in the air. Flew about 500 feet videoing the area, and then started to return and come down at the same time. Last time I looked it said 76 feet, I was distracted by a bystander for a moment, and the drone was in the marsh grass.
I had quite a time retrieving it, but it was still on, motors off, lights blinking. I could not re-connect, I was 100 feet into the marsh after traversing a stream in a kayak, so I did not have the tab and RC with me.
I turned off the bird, returned to the car, and sighed a breath of relief that the bird did not take a swim. Later I meticulously cleaned the beauty, and the motors ran. I flew the next day for 20 wonderful minutes at all altitudes, so the bird is OK. Whew.
However I think it crashed, somewhat because I wasn't watching it, but the tab said 76 feet up, I thought I was sinking slowly, looked away for less than a minute, and it had crashed. Could the altitude readings be that far off?
Just asking... Thanks.

My theory on why the shift occurs: At the beginning of the flight the sensor is at ambient temperature;
after about 10 minutes of flying the altitude sensor's temperature has increased due to localized heating inside
the aircraft; this increase in temperature is affecting the output of the altitude sensor. I'll bet that the shift will be smaller during my up and coming winter flights! I wonder if anyone at DJI can comment on my theory??

tflanagan17 Posted at 2015-9-28 08:45
My theory on why the shift occurs: At the beginning of the flight the sensor is at ambient temperatu ...

Absolutely!  exactly what I thought and that is why the error is always in the same direction.  I have a small digital barameter, thermometer that stores the data in memory that is suppose to be here today that I am going to attach where my trackimo usually sits to see if I can detect temperature changes.   Don't know if this will do it or not but I cannot wait to try it out and see.

Here's what I am seeing.

http://forum.dji.com/thread-31951-1-1.html

No response from my DJI dealer.

I am hoping I can attach this digital data logger to the P3 and then Hopefully I can get the data downloaded off of it.  It records Barometer, Humidity and Temperature for every second.  It was not a very intuitive device to program and I am hoping I can use the results to see if there is correlation between the temperature increase as the bird flies and the loss of  relative altitude.  It does not quite fit the Trackimo bracket on my P3 but I should be able to tether it.

Folks I complained about this months ago,  When my p3p would show 30 to 60 ft altitude at ground level upon the return from a flight, when the shell cracked, that was enough for me.  I decided to return the p3p I bought an Inspire the Inspire returns once in a while and shows negative 3 ft,  sometimes it shows positive a couple of feet. it varies about a meter, and somtimes it is very accurate so go figure.  I bought a p3A  the p3a is very accurate and returns to ground level after every flight with a almost perfect reading at ground level everytime,  I would imagine that there is different manufactures of the baro sensor, different factories , runs and component design even. I have tried to determine if the ambient start temp is a factor or warm up and restart a factor in temp of the bird, I cannot find a definite pattern the baro sensor either works right or it dosent,  I think you will have to send your bird in if you ever expect to have it work correctly.

Let your unit set on the ground after you have everthing lit up, dont start the motors after 5 to 10 minutes you will probably get an error 43  (I think the error no, is 43, I forget)  if you get the error your motors will not start your baro sensor is bad. read my posts above this one I hope this helps