Hi All,
I am off to Scotland at the beginning of October and fingers crossed the weather will be good to fly - at least some of the time.
My question is regarding flying above 400ft from TOAL. If I am stood near the bottom of a hill or mountain, which slopes upwards (not talking about a sheer cliff here), is it breaking the rules to travel up that slope to above 400ft, even though you are never e.g. 30-50m above the ground?
I just wanted to check this out before I went.
Thanks in advance for your help.
Steve
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As long as you are never 400 above the ground you are flying you will be good mate, DJI will just throw up a few warnings making you aware that your over 400ft from TOAL. You will have to derestrict your height limit if you have it set. 
Hope this helps and I’m understanding your question in correctly. 
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Thanks Steve, I was hoping that would be the answer. It will certainly help save my lungs for other treks lol.
I did it recently at Cheddar, TOAL from the road, then adjusted to 400ft over the gorge, worked out around 700ft in total, a few OK clicks on DJI go and it was happy again. 
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Many thanks Rich. I am aware of the rules but was a little unsure as to whether this was above TOAL position, but obviously not. Just wanted to be certain so that I was staying legal.
@McSteamy2010 What warning could be thrown up as my understanding is 120m up from where you’re currently stood, be that at the top of a hill, middle or bottom of the hill, 120m is always 120m.
I’m not being argumentative just cannot fathom why there would be any warnings at all.
Thank you
@McSteamy2010 what did you adjust over the gorge? (never been so no idea of layout)
Sorry to be a pain.
If your stood on the road at the base of the Gorge the cliff tops are approx 80-100m above you, so when it comes to taking off from the base you only have 20m to play with above the top. so…
once you’ve reached maximum height and you change the height setting to be above the restricted 120m Go4 then warns you that your going over the legal limit. The drone doesn’t know the landscape, so although I’m 600ft above my take off point I’m actually only 300ft from the tops of the cliffs.
hope this makes sense and your following.
The height settings within the flight app. 
@McSteamy2010 Got it! i was thinking along the lines of the Gorge being ‘down’ from road level by 300 ft.
Sorted now. Thank you.
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The wording is
“Your drone or model aircraft must never be more than 120m (400ft) from the closest point of the earth’s surface.”
I’ve wondered if the vertical surface of a cliff is classed as the earth’s surface. I think it is.
This is where your TOAL comes into play though. There’s already a few videos knocking about on YouTube about this. I know it’s a problem with the Mini and if you use the same Fly app, I assume its the same.
The Fly app will always assume your height from your TOAL location, it doesn’t know if after say 400 yards that you’ve flown over the edge of a cliff or are going up a hill. It will assume you’re at the same height regardless.
E.g. if you take off at the top of a hill, fly forwards and go down, you’re height reading will have a minus number!!
So you may find you’re getting nowhere near the height you want, unless you stop your flight and take off again.
Dunno if someone else with more expertise has an opinion on this, the answer it to probably ‘modify (aka hack) the app’
No need to mod the app, set maximum altitude to 500m
Or if you really want to be anal you could pre plan a flight in litchi. Run it though a sim and set the maximum height according to your findings.
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400 ft from closest point of the earth,not 399 not 410,no brainer,I post my intended flight with police 101 every flight ,I fly A2 I am insured,I log my mobile number and respect people’s privacy ,unless your bird is huge ,line of sight becomes difficult depending on light,because you can see it on controller or phone that’s not clear line of sight or the ability to maintain direction,try flying in the dark really be real and safe
Why ?
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How accurate is the barometer in a drone? Is air pressure a constant?
Although what is the legal maximum?
If it is 120m then that is 393.7 feet and not 400 feet.
If it is 400 feet then you can go up to 121.92m
Good diagram, which captures it perfectly. It’s 120m (not 400 ft, as someone noted) measured in any direction from any part of the surface of the earth.
One big but. Manned aircraft should not fly below this height if people around, but the reality is they often do, especially in less busy areas, such as Scotland. In the Highlands and western Scotland, it’s well worth getting familiar with the dedicated low-flying areas as well, where aircraft can and will fly well below the normal 500 ft floor.
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If you’re staying in Blair Atholl caravan park nothing disturbs the quiet relaxation of your morning coffee more than a couple of jets screaming over your head from the direction of Glen Tilt as you sit on the deck taking in the view. And they do come in low 
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