I'm new, 2days old,.................the  specs on the P4 says........... Altitude is 19,685 ft.
i have read where thats not possible. I have also read and view videos where folks have taken the P4 to 1600 ft .
If the software limits you to 400 ft why do the specs  contridict this??
I realise what the FAA say (400') but  why are the spes worded the way they are.
I'm wondering what else the specs are wrong?
If i'm in the valley and want to go to the top of a 900' mt. I can......or CAN i SOMEHOW?
Can the software be modified to an altitude say, 700'???
Thanks
Ralph

In the mountain scenario, its feet above take off spot, so if you are limited to say 400ft then you cannot go above , but if you took off from the top of the mountain thats 900ft
then you can in effect fly at 1300ft

The 19,685 feet is the service ceiling.  In other words, if you start out at  that altitude it can't fly any higher because of physics.  The legal limit is 400 feet above take-off point.  You can set the max altitude up to 500 meters or 1640 feet.  After that, you can not set any higher.  If you are 3000 feet above sea level when you take off, you can fly all the way down to sea level, negative numbers with regard to take-off point.  But legally, you could not fly higher than 3400 feet.  Hope this helps.

You need to understand the difference between height above sea level and height above the ground. The drone rules in different countries normally refer to a height above ground level which is the ground you are standing on. But the ground you are standing on could be several thousand feet above sea level.
So, for example, you are flying from a place that is 3000 ft above sea level and the rules state you can only fly to a maximum height of 400ft. The 400ft will be above ground level so if you fly to 400ft above ground level then you are 3400ft above sea level.
In the specs on the P4Pro, they refer to the maximum height above sea level.

Jenee 2 Posted at 2017-12-9 22:27
You need to understand the difference between height above sea level and height above the ground. The drone rules in different countries normally refer to a height above ground level which is the ground you are standing on. But the ground you are standing on could be several thousand feet above sea level.
So, for example, you are flying from a place that is 3000 ft above sea level and the rules state you can only fly to a maximum height of 400ft. The 400ft will be above ground level so if you fly to 400ft above ground level then you are 3400ft above sea level.
In the specs on the P4Pro, they refer to the maximum height above sea level.

Slight correction, in terms of the 'legal' height, it is not the height above where you are standing, it is the distance between the aircraft and the ground directly beneath it.

OK box361
I'm going to give you a small crash course in aviation ops and pressure altitude factors
First, yes, your P4 is software limited to 500 meters or about 1600'; the very important factor with that is it is above the takeoff elevation.  In other words, if you take off at sea-level you can go no higher than 1600 feet MSL (Mean Sea Level) which would also be AGL (Above Ground Level).
Therefore, if you go to the top of Pikes Peak and takeoff you can ascend to an altitude of 15,715 feet MSL, yet, you will only be going to an altitude of 1600 feet AGL
I'm thinking at this point you have figured out that you can fly to much higher altitudes than you might have been thinking otherwise.  So, here is the next factor to consider.  I'm not going to go in to all the various calculations to support flight performance factors etc. etc. so here is the quick and dirty.  The higher you go the thinner the air, the thinner the air the harder it is for air foils to produce lift and in this case for a quadcopter it makes it more challenging to maintain stability.  All that means is that DJI has determined that at 19685 ft MSL the quad cannot fly reliably enough to sustain controlled flight.  This makes that altitude the P4s max operating ceiling.

Lastly, do not confuse operating limits, with design limits, software limitations, and regulatory limits.  All in all if a P4 has a range of say 4 miles then it should easily be able to fly to an altitude of 21,120 above your takeoff point and from your Remote Controller.  However, DJI through FW has limited your ability to fly no higher than 1640 feet above the take off point, and the rest has been discussed or noted.

If you modify the SW you will negate the warranty and any hope of DJI supporting you if something goes wrong.  
In your example, if you attempt to takeoff in a valley and then fly to a mountain 900 feet higher you should be able to.  FAA rules are 400 feet AGL and the mountain is not higher than the takeoff point by 1600 feet.

The max distance and height of phantom 4pro is exactly the same, so yes it can fly as high as it can far, but first you are curbed by limits set in P4Pro regarding altitude to 500 metres and legal limits of usually 120 metres, safety to manned aircraft is paramount so best to stick to your countries rules.

Aloha Ralph,

     The responses to your posted thread have given you good information.  But Genghis does provide the crash course you need on this subject.  The only thing I can add is that the FAA regards your valley and mountain as "structures" and our Phantoms are allowed to fly within 400 feet of a structure.  Manned aircraft are supposed to stay 500 feet away from structures.  So according to the Pt. 107 rules, you can fly 400 feet higher than your 900 foot mountain.  That is why DJI computer limits your Phantom to 1640 feet, or 500 meters.

     Hope this helps!

Aloha and Drone On!

Jenee 2 Posted at 2017-12-9 22:27
You need to understand the difference between height above sea level and height above the ground. The drone rules in different countries normally refer to a height above ground level which is the ground you are standing on. But the ground you are standing on could be several thousand feet above sea level.
So, for example, you are flying from a place that is 3000 ft above sea level and the rules state you can only fly to a maximum height of 400ft. The 400ft will be above ground level so if you fly to 400ft above ground level then you are 3400ft above sea level.
In the specs on the P4Pro, they refer to the maximum height above sea level.

... INDEED !!

Geebax Posted at 2017-12-9 22:31
Slight correction, in terms of the 'legal' height, it is not the height above where you are standing, it is the distance between the aircraft and the ground directly beneath it.

so then if i'm standing in a valley, and I take off straight  up it's 400' max, however if I fly over to a nearby mt. that's 1000 ft high,..... as long as the aircraft sees the ground below it , ...it will continue to 400' above the top of the mt?    which would be a total height from ME  of 1,400'....correct??
Also, thx to all for the info.

box361@frontier Posted at 2017-12-10 04:11
so then if i'm standing in a valley, and I take off straight  up it's 400' max, however if I fly over to a nearby mt. that's 1000 ft high,..... as long as the aircraft sees the ground below it , ...it will continue to 400' above the top of the mt?    which would be a total height from ME  of 1,400'....correct??
Also, thx to all for the info.

The Phantom cannot tell how high it is above the ground.
You have to work that out.
The Phantom only knows how high it is above the level of its launcg point.

I is as Labroides said.  The Phantom does not "see" the ground in that way.  To keep it simple, legally, you can fly up to 400 feet above the ground level where you  take off.  If you fly up the side of a mountain, as long as that mountain is 400 feet or less below you, you are ok.  But if you try flying higher than 1640 feet above your take-off point, you can't due to software limits.  So, if you take off from the base of the mountain, and the mountain is 2000 feet tall, you can only fly 1640 feet up the side before software limit .  But if you take off from the edge of the Grand Canyon and fly out over the canyon, you are instantly much higher than 1640 feet.  And as far as the Phantom is concerned, it is at 0 feet, plus however much it went up when it took off.  It could still climb 1640 feet from this point over the Grand Canyon.

box361@frontier Posted at 2017-12-10 04:11
so then if i'm standing in a valley, and I take off straight  up it's 400' max, however if I fly over to a nearby mt. that's 1000 ft high,..... as long as the aircraft sees the ground below it , ...it will continue to 400' above the top of the mt?    which would be a total height from ME  of 1,400'....correct??
Also, thx to all for the info.

What you might do in that situation is use a tool like daftlogic.com to measure the height of the launch point and also the height of the mountain or hill or whatever.  Whatever the difference is, keep that number in your head, and then when you fly, you can add that to whatever your app is showing to give you the approx AGL vertical distance when you're over the mountain/hill.  

Re the 2000 foot mountain peak problem, there might be a loophole although I don't think anybody has ever tried it or ever will.  But theoretically you could fly half way up the mountain, land on some ledge, stop the motors, re-mark the home point, check your app, and if it says height is zero, you could restart your motors and head up to the top.  Regarding the "never launch on a partially charged battery" rule, it's been stated many times that it's relatively safe to do that if the AC isn't turned off - which is to mean the battery reading you see won't be false.  


This is just my theory.  I think I'll test it soon on a small hill just for fun...