Mechanically, how high can I go?

[NRJ]

With common sense you are quite correct, technically (and being pedantic just for a moment) the height you are flying is measured below aircraft in flight, NOT where you are standing. It may be the same if dead flat and you are above your take off point, but fly off a mountain (your example) sideways & your Phantom could end up way above 400 AGL & illegal height. Just food for thought, I'm not attacking anyone, just prompting understanding (hopefully).

Your argument has merit, however, when I do fly off a cliff such as Zuma Beach in Malibu CA, the app tells me the measurement from my starting point. Because DJI is more regulated to use proper measurements AGL, and what I have said is in agreement with them, chances are, they are more right therefore I am also right, wouldn't you say? Along with that, when I go up 50 ft over where I am standing, and I fly straight out over the cliff, I am at 50 ft height AGL even though the distance truly at AGL is about 200 ft. And if I fly below where I am standing, it tells me I am at -50 ft. Use your own judgement from the facts as presented but verify for yourself too. Thanks for the thought and the input. Happy flying.

 

[Meta4]

when I go up 50 ft over where I am standing, and I fly straight out over the cliff, I am at 50 ft height AGL

AGL stands for above ground level and it refers to the ground level immediately below your Phantom.
If the ground is 200 feet below your Phantom your Phantom's altitude is 200ft AGL.
Whether you launch from the top or bottom of the cliff is irrelevant.

 

[NRJ]

AGL stands for above ground level and it refers to the ground level immediately below your Phantom.
If the ground is 200 feet below your Phantom your Phantom's altitude is 200ft AGL.
Whether you launch from the top or bottom of the cliff is irrelevant.

Can you give me a link that has something in writing to confirm what you are saying? I have read many threads on this and everyone seems to be confused. Not to be picky, but the FAA says; "at (not above) ground level. But, I like and can relate better to above ground level. I have to go at this point with what the app tells me when I'm flying just like your example. It tells me my AGL from where my homepoint is. So, till I can get something authoritative in writing, I politely disagree with your finding. Thanks.

 

[Meta4]

I have read many threads on this and everyone seems to be confused. Not to be picky, but the FAA says; "at (not above) ground level.

I'm not sure where you got that idea from. It doesn't make any sense
At ground level is ground level.
About 3 seconds on Google will show that AGL is Above Ground Level.
Or to see what the FAA says: Definitions
Or: http://atbasics.faa.gov/secured/pdfs/SLP 01-Resources.pdf

Can you give me a link that has something in writing to confirm what you are saying? .... But, I like and can relate better to above ground level. I have to go at this point with what the app tells me when I'm flying just like your example. It tells me my AGL from where my homepoint is. So, till I can get something authoritative in writing, I politely disagree with your finding.

Your app does not give you AGL anything.
It's telling you how high your Phantom is above launch point which is not AGL unless you are somewhere flat.
In my illustration the phantom's altitude (agl) is how high the Phantom is above the ground (which is below it) and where it was launched from is irrelevant.
The term above ground level is self explanatory and shouldn't need any explanation.
But if you need it spelled out try this:
What is the difference between Above Ground Level and Above Field Elevation?

 

[Loz]

..he app tells me the measurement from my starting point. Because DJI is more regulated to use proper measurements AGL, and what I have said is in agreement with them, chances are, they are more right therefore I am also right, wouldn't you say?

Hi NRJ, with respect in response to your question 'No' - the point you make and conclusion is wrong, which is why I, and then Meta4 have taken the time to explain and provide you with explanations, drawing (brilliant I thought) and references. This is not about one being right or another wrong it's about knowledge sharing and clarification of often confusing points. In this instance your conclusion was incorrect, hopefully you've followed up the references and can see that, I wish you well and happy to try explain anything you may wish to clarify further.

Height AGL and legal max height (differs per country) are important concepts to understand.

 

[Loz]

I have to go at this point with what the app tells me when I'm flying just like your example. It tells me my AGL from where my homepoint is. So, till I can get something authoritative in writing, I politely disagree with your finding. Thanks.

NRJ this sounds like the earth is flat argument of yester-year. The reason they have pilot licences is to learn and understand what the instruments are telling a pilot to fly safely. Likewise understand the limitations of the Phantom Instruments - the app, its telling pilot height above or below take off point (as you appear to have confirmed) NOT height above ground (AGL). The app gets this info from a Phantom built in barometer that measures air pressure, it has NO concept nor tries to understand height AGL, only height (air pressure)change from take off point.

Now back to fly off mountain example - the air pressure is same (for purposes of this example) when a Phantom flies sideways away off the top or side of a mountain, so displayed 'height' on DJIGo app will stay same, but we know that the phantom is actually now possibly hundreds of feet above the valley below the Phantom (AGL), and quite possibly flying way above legal / recommended flight height. Make sense? hopefully.

 

[jwmcgrath]

The twist this thread has taken now becomes even more fascinating when we factor in "above sea level."

Because if you are standing at 5,999M up the side of a mountain, then theoretically when the guy standing next to me says "hey that's cool, how high can you go?" my answer now becomes "1M".

...right?

 

[neven]

If firmware 500m limit is removed P3 can fly up to service ceiling of 6.000m ASL without crashing or breaking any rules/laws/guidelines

 

[sar104]

The twist this thread has taken now becomes even more fascinating when we factor in "above sea level."

Because if you are standing at 5,999M up the side of a mountain, then theoretically when the guy standing next to me says "hey that's cool, how high can you go?" my answer now becomes "1M".

...right?

It did seem like there was a persistent misunderstanding in parts of this thread about the difference between the physical capabilities of the aircraft, the software limitations of the FC, and FAA guidelines/regulations.

The 6000 m MSL (height above mean sea level) operational ceiling quoted by DJI is just their estimate of the height at which the air becomes insufficiently dense to provide lift. So if you tried to take off at 5999 m MSL then you might, or might not succeed, but the aircraft will be barely able to stay in the air, let alone climb out of ground effect.

The 500 m maximum altitude (above takeoff point) is a DJI software limitation on how high the aircraft will climb above the takeoff point, completely independent of the elevation of the takeoff point or of the elevation of the surrounding terrain. So if you take off and fly off a cliff or mountain you could be much higher than 500 m AGL (above ground level at the location of the aircraft), but still less than 500 m above the takeoff point.

The FAA restriction of 400 ft AGL is just a guideline or rule, depending whether you are flying recreational or Part 107, and it refers to the altitude of the aircraft above the ground over which it is flying, not above the takeoff point.

 

[wolf~928]

I take off @7000ft ASL every time I fly. Fly directly off my mesa, and at 100 ft straight out ,,my altitude is 0 ft,,but the bird is physically 200 AGL.. and as NRJ has said if I go lower it will read - alt..

 

[wolf~928]

So I know my ceiling out here is set to 200'

 

[sar104]

So I know my ceiling out here is set to 200'

I'm not sure that you are using the term "ceiling" correctly. The aircraft is showing its altitude simply as height above the takeoff point, so of course it will show negative if you fly below that. It says nothing about your ceiling, which is an unspecified limit until you define whether you mean software-regulated limit or performance limit.

 

[jwmcgrath]

It did seem like there was a persistent misunderstanding in parts of this thread about the difference between the physical capabilities of the aircraft, the software limitations of the FC, and FAA guidelines/regulations.

The 6000 m MSL (height above mean sea level) operational ceiling quoted by DJI is just their estimate of the height at which the air becomes insufficiently dense to provide lift. So if you tried to take off at 5999 m MSL then you might, or might not succeed, but the aircraft will be barely able to stay in the air, let alone climb out of ground effect.

The 500 m maximum altitude (above takeoff point) is a DJI software limitation on how high the aircraft will climb above the takeoff point, completely independent of the elevation of the takeoff point or of the elevation of the surrounding terrain. So if you take off and fly off a cliff or mountain you could be much higher than 1500 m AGL (above ground level at the location of the aircraft), but still less than 1500 m above the takeoff point.

The FAA restriction of 400 ft AGL is just a guideline or rule, depending whether you are flying recreational or Part 107, and it refers to the altitude of the aircraft above the ground over which it is flying, not above the takeoff point.

Very well phrased, and thorough.

And yes, I agree that there are various ways people have misunderstood some stats throughout the thread, myself included. Part of mine is simply misreading.

To reiterate, when standing in the park, there is NO specific number to give when asked how high it can go, because statistically, that's dependent on a number of factors.

Of course the standard "it could go 6000M, if it wasn't limited to 500M by firmware or 400' by FAA guidelines" answer still applies... but even that is factually incorrect if you are already standing at 4000M ASL.

As a demo, and as a non-107, standing in a "manned aircraft-free" area, at sea level, you should be able to do a casual, problem free ascent to 500M.

 

[wolf~928]

Set in software to remain at the 400' AGL, I am thinking of this correctly no? If not could you explain?

 

[jwmcgrath]

Set in software to remain at the 400' AGL, I am thinking of this correctly no? If not could you explain?

Once you hit 400' AGL, the DJI Go app advises that you have reached the safe preset altitude. You simply have to acknowledge and clear the warning to continue ascending.

Following that, the firmware will limit ascent to 500M and there is no overriding that one.

 

[sar104]

Set in software to remain at the 400' AGL, I am thinking of this correctly no? If not could you explain?

The default software limit is 400 ft (can be increased to 500 m) but that is not AGL - it is "above takeoff point". If that is your setting then the aircraft will not go above 400 ft as indicated as its altitude. I still don't understand what that has to do with flying off a cliff and going down into negative altitudes though.

 

[wolf~928]

I take off @7000ft ASL every time I fly. Fly directly off my mesa, and at 100 ft straight out ,,my altitude is 0 ft,,but the bird is physically 200 AGL.. and as NRJ has said if I go lower it will read - alt..

Ok ,so it doesn't matter that I take off 200' above where I'm going to fly?

 

[jwmcgrath]

The default software limit is 400 ft (can be increased to 500 m) but that is not AGL - it is "above takeoff point". If that is your setting then the aircraft will not go above 400 ft as indicated as its altitude. I still don't understand what that has to do with flying off a cliff and going down into negative altitudes though.

I just did it again... didn't meant to say AGL in my post, I made the continuing fatal mistake of imagining flat land.

It's just occurring to me now... It probably makes a huge difference if you live where it's flat and live where it's not when addressing topics like this.

 

[sar104]

Ok ,so it doesn't matter that I take off 200' above where I'm going to fly?

Doesn't matter at all. The software limit only controls how high you can fly above your takeoff point.

 

[jwmcgrath]

Ok ,so it doesn't matter that I take off 200' above where I'm going to fly?

Depends what you are asking and what you are trying to do! By saying "it doesn't matter"... WHAT doesn't matter?