The altitude problem.

[Meta4]

AGL ... MSL .... etc. but they cannot be determined by the flyer of his drone. All he has is Take Off point referenced height which is only AGL on his display when AC is directly over that point. Everywhere else its just BS.

What's also irrelevant to regulation, is the height shown on the display.
That's just there for convenience.
Everyone knows that this is not the actual AGL height unless you are flying on a large, flat plain.
Flying over terrain, the drone pilot has to do what the pilot of a Cessna does ... estimate and use mental arithmetic and common sense because most small GA aircraft also have no sensor capable of displaying actual height above the ground..

 

[N017RW]

Totally agree with that .... what you and Meta4 miss in my PoV is that the AC when it flies over the head of that Inspector, in his interpretation of the rules AGL is based on where he is standing ... not the flyer with RC up the hillside.

Car Park !!!! That's funny !!

The fundamental problem here is the derivation of the height the AC is flying at. The display and flight log all list it as relative to take off point as Zero. As the AC moves out from the hillside over the valley - it is displaying the same referenced height. So saying take off point is irrelevant is 100% wrong. It is relevant to the person controlling the AC.
When it comes to another person IN THE VALLEY - if the AC hovers above his head regards the AC height as referenced to directly below that AC where he is.

As I see it and it has been a subject of debate in the Group I am in who report to EU / Latvian Aviation Authority - the problem is interpretation of what is the actual height reference ... So far on this and other forums I frequent and the Larpas group mentioned - a definitive statement is yet to be made. People SAY they have it ... but in fact they don't.
People love to quote Aircraft terms such as AGL ... MSL .... etc. but they cannot be determined by the flyer of his drone. All he has is Take Off point referenced height which is only AGL on his display when AC is directly over that point. Everywhere else its just BS.

What a mountain out of a mole-hill.

Pun intended.

 

[captainmilehigh]

Over-thinking AGL a bit here. Keep it simple, because it is.

 

[solentlife]

As far as I understand this situation you are not within 400ft if you launch from top of the hill and you stay within your 100m above launch point while you fly over the valley which is 1000m below. You are then actually 1100m from the ground as nobody will know from where you took off and the same is with the pilot of the aircraft which may fly along this valley.

At least someone else has got it ......

 

[solentlife]

I've read that 3 times and still can't work out what you are saying.
Going back to what you wrote previously, doesn't make much sense either.
btw .. The man in blue is the hypothetical inspector.
For him or anyone else, AGL is height above the ground, and the ground being referred to is always the ground directly below the aircraft.
There's no other way to interpret it and my diagrams make that pretty clear to everyone else.

At last we can agree on something ....

Your picture makes a fundamental error when you explain. Because the AC are over the hill and of course AGL of 100ft is 'legal'. You stick to the two flyers A & B and their AC's being up there. But that is not the point of the original post of this thread ...
It is when they fly over the valley ... out over the head of the man in blue they are no longer in his eyes at 100ft .... to him they are at much greater AGL. I just added the point that if he's an **** Inspector - he may just try to prove his point and grab you.

I'm trying hard to stay on point of the original first post and the "mountain out of a mole hill" is because of others failure to grasp that simple point of the AC is no longer over the hill ... but out over the valley ....

If you cannot grasp that concept - then there's little hope for the quad world !! No wonder Authorities tend to ignore the model community !!

 

[Meta4]

If you cannot grasp that concept -

There were no misunderstandings in this thread until you came in.
You said some things that made no sense and then did it some more.
Like all other participants in the discussion, I have a good grasp of the concepts and make an effort to communicate clearly to avoid confusion.

 

[solentlife]

There were no misunderstandings in this thread until you came in.
You said some things that made no sense and then did it some more.
Like all other participants in the discussion, I have a good grasp of the concepts and make an effort to communicate clearly to avoid confusion.

So please explain why your replies do not relate to OP's original question ...

"
I'm sure that this was discussed already but I just couldn't find it.
Taking off from the hill and ascending to let say 100m. Then you fly at straight line forward away from the hill keeping the same altitude.
But the slope of the hill quickly causes the altitude to become a few 100 m from the ground, although you have still 100m on the display.
How can one keep the drone below those 120m (400ft) if the distance to the ground is not known in such circumstances? "

His post clearly indicated that the AC moves OUT away from the elevated take off point - making the AC's true AGL different to displayed numbers on screen.
Your posts have consistently stuck on the AC staying above the take-off point. Look at your OWN cartoon pictures ....

I was not only one who noted the significance OP wrote.

In completion of my STAYING ON OP's TOPIC ..... to keep below the 400ft even when out over the lower ground requires information that DJI are not able to provide in GO / GO4. As to whether it is actually required that you stay 400ft by following changing ground contours as it changes is NOT specifically answered in any Ruling - despite some claims. The ruling is contentious at best and open to interpretation of the authority involved.

Bye !

 

[Meta4]

So please explain why your replies do not relate to OP's original question ...

It seems to have escaped you so I'll spell it out.

If you look back you would note that I addressed the OP's question clearly and succinctly in post #6.

Another member joined in with some different comments in post #8.
Someone else with an unconventional point of view came in with post #10, which was quickly debunked in post #11.
I also replied to post #8 and post #10 at the same time with an illustration to show why post #10 was not correct.
But the poster from #10 was confused and failed to understand. He came back to obfuscate with wordy and incorrect posts # 14, 18, 19, 24 & 25.

As for the rest of post #27, the poster still is having comprehension difficulties and making a simple issue unnecessarily complicated.

And that, sir is why some of my posts were not relating to the OP's question which had been answered long ago.
Once a question has been answered, there's no need to keep going over it again and again.

 

[solentlife]

Not banning me this time then for having a different viewpoint ?

You still missed the boat ... the AC moved away from the hilltop .... is that not understood by you ?

Go on ... ban me again for daring to differ. I made valid point. Subsequent posts were to defend and try to get you to comprehend the AC was not still over the take-off point .... a fact you persistently failed to grasp - even to the point of drawing a diagram - Illustrating your continued mistake.

Unbelievable.

 

[Meta4]

Not banning me this time then for having a different viewpoint ?

I don't think that having impossible comprehension problems is a banning offence.

You still missed the boat ... the AC moved away from the hilltop .... is that not understood by you ?
I didn't see that in the diagram.
The whole thread moved on after post #6 ... is that not understood by you?

Go on ... ban me again for daring to differ. I made valid point. Subsequent posts were to defend and try to get you to comprehend the AC was not still over the take-off point .... a fact you persistently failed to grasp - even to the point of drawing a diagram - Illustrating your continued mistake.

Just take my word for it and stop embarrassing yourself. You've really missed the boat on this one.

Unbelievable.

I can agree with you completely on that anyway

 

[solentlife]

Printed of the thread as a crass example of Darwinism ......

Amazing.

 

[Meta4]

Truly amazing

 

[sar104]

In completion of my STAYING ON OP's TOPIC ..... to keep below the 400ft even when out over the lower ground requires information that DJI are not able to provide in GO / GO4. As to whether it is actually required that you stay 400ft by following changing ground contours as it changes is NOT specifically answered in any Ruling - despite some claims. The ruling is contentious at best and open to interpretation of the authority involved.

Bye !

I'll add that I'm confused by your statements here. In the US, §107.51 requires staying below 400 ft AGL (= above ground level), so what do you mean by "NOT specifically answered in any Ruling". Are you arguing that the term AGL is not clearly defined, that US law doesn't apply until it has been tested in court, that this law doesn't apply to §101, or something else?

 

[solentlife]

I'll add that I'm confused by your statements here. In the US, §107.51 requires staying below 400 ft AGL (= above ground level), so what do you mean by "NOT specifically answered in any Ruling". Are you arguing that the term AGL is not clearly defined, that US law doesn't apply until it has been tested in court, that this law doesn't apply to §101, or something else?

Not arguing with the 400ft above ground ... we have similar ruling over here as most countries do.

The question is what happens as the AC moves away from the hill top where it was launched, as in OP's first post.
This is where others have ignored the moving out from the hillside and over the valley.

My original reply was not a statement but a suggestion that anyone standing in the valley with the AC now above them would regard it as being higher than the person who is looking at his Go display after take off from the higher point. A fact that has been subject of debate I know in various discussion groups including LARPAS, which I am an active member of. The debate has been further muddied because of many peoples interpretation despite numerous cut and paste links by various.
There are the 400ft over top of any structure - even a mast ... 400ft over ground ... 400ft allowed out to 400ft horizontally from a structure .... the list of possibles goes on and on. The fact is the simple statement of 400ft AGL has led to debate not only on forums but also in Govt appointed groups such as our LARPAS. Look at AMA and FAA ... CAA and BMFA (actually BMFA and CAA have got closer to agreement than any other !).

I was illustrating that the Pilot will regard his AC as still at 100ft as example referenced to Home Point, but the other person 400ft below in the valley who now has the AC above him would say the AC is now at 500ft ... and could, if that person was an efficious son of ****, lead to authority action.
AGL is AGL we all accept that ... trouble is DJI has not given us a tool to keep to terrain following AGL. DJI data of our flight - the only true AGL is over the home point.

The OP was asking how to do it. Because as a person in the street - he's obviously unsure what is the real answer. As it appears are many others ...

I do not profess to know the answer of how to satisfy the AGL limit when the ground is not level - as I say - its been a debated subject in LARPAS and because of the tools we have in hand when we fly creates a difficulty to determine actual AGL through the flight.

 

[Meta4]

trouble is DJI has not given us a tool to keep to terrain following AGL. DJI data of our flight - the only true AGL is over the home point.

I do not profess to know the answer of how to satisfy the AGL limit when the ground is not level - as I say - its been a debated subject in LARPAS and because of the tools we have in hand when we fly creates a difficulty to determine actual AGL through the flight.

Nigel .. I realise this is a very, very difficult subject for you but if you just go back to post #6 you'll find a complete and accurate answer to this very troubling matter.
You've said your piece, and said it again and again.
We've seen what you think.
Now can you give it a rest please?

 

[sar104]

Not arguing with the 400ft above ground ... we have similar ruling over here as most countries do.

The question is what happens as the AC moves away from the hill top where it was launched, as in OP's first post.
This is where others have ignored the moving out from the hillside and over the valley.

My original reply was not a statement but a suggestion that anyone standing in the valley with the AC now above them would regard it as being higher than the person who is looking at his Go display after take off from the higher point. A fact that has been subject of debate I know in various discussion groups including LARPAS, which I am an active member of. The debate has been further muddied because of many peoples interpretation despite numerous cut and paste links by various.
There are the 400ft over top of any structure - even a mast ... 400ft over ground ... 400ft allowed out to 400ft horizontally from a structure .... the list of possibles goes on and on. The fact is the simple statement of 400ft AGL has led to debate not only on forums but also in Govt appointed groups such as our LARPAS. Look at AMA and FAA ... CAA and BMFA (actually BMFA and CAA have got closer to agreement than any other !).

I was illustrating that the Pilot will regard his AC as still at 100ft as example referenced to Home Point, but the other person 400ft below in the valley who now has the AC above him would say the AC is now at 500ft ... and could, if that person was an efficious son of ****, lead to authority action.
AGL is AGL we all accept that ... trouble is DJI has not given us a tool to keep to terrain following AGL. DJI data of our flight - the only true AGL is over the home point.

The OP was asking how to do it. Because as a person in the street - he's obviously unsure what is the real answer. As it appears are many others ...

I do not profess to know the answer of how to satisfy the AGL limit when the ground is not level - as I say - its been a debated subject in LARPAS and because of the tools we have in hand when we fly creates a difficulty to determine actual AGL through the flight.

OK - so you are not arguing that there is ambiguity in the requirement - just that the onscreen display doesn't indicate height AGL? Unfortunately the lack of that indication doesn't change the requirement, any more than driving without a speedometer exempts you from speed limits.

The CAA explicitly addressed the operational meaning with regard to terrain in CAP1687:

I don't see any room for confusion there. In the US, Part 107 mentions flying within 400 ft of structures but doesn't, specifically, address lateral spacing to terrain features. I think that most Part 107 pilots work under the reasonable assumption that a similar requirement applies, since it would otherwise be physically impossible to fly over a vertical cliff compliantly.

In any case this seems to me to be an unnecessarily complicated (and bad tempered) discussion, because the OP's question wasn't even about the cliff problem - it was just about whether you are required to maintain less than 400 ft AGL as the terrain changes elevation. There is surely no ambiguity about that question in the US or the UK - Part 101 excepted.

 

[Andy9]

This discussion is really going over any resonable arguments.
My original question was answered but not completely. It is clear, that flying away from the hill top will violate the rule of max. altitude allowed. But the problem remains as operator will never know at which poiint he is over 400ft. It will always be only an estimation.And the authority won't know that either.

 

[solentlife]

Thank you sar104 .....

1. For understanding my point.

2. For putting a better and RELEVANT diagram to the thread.

3. And finally for a pleasant and well mannered post.

LARPAS is still putting together its latest notes for Latvian CAA and the EU body ... with work - I have not caught up with all their latest data incoming - but will be anyway as part of the usual spring meetings.

 

[solentlife]

This discussion is really going over any resonable arguments.
My original question was answered but not completely. It is clear, that flying away from the hill top will violate the rule of max. altitude allowed. But the problem remains as operator will never know at which poiint he is over 400ft. It will always be only an estimation.And the authority won't know that either.

Exactly.

Thank you and my apologies for the exchange I was involved in that 'coloured' your thread.

 

[sar104]

This discussion is really going over any resonable arguments.
My original question was answered but not completely. It is clear, that flying away from the hill top will violate the rule of max. altitude allowed. But the problem remains as operator will never know at which poiint he is over 400ft. It will always be only an estimation.And the authority won't know that either.

Your full flight track is in the flight log. Once imported into a program with a DEM, such as Google Earth - that will show height AGL. Alternatively, if you post photos or video, height AGL can be seen in the EXIF data or simply estimated from the field of view of the camera. So it would be unwise to assume that the FAA or other LE authorities would be unable to verify whether you broke the law.