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Method to determine increased elevation from launch point

maggior

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Something I have started doing is looking at increasing my max altitude based on the terrain. To do this, I've been using the Terrain layer of Google Maps to determine the elevation changes and measuring the distance to them. For instance, behind my house, if I fly 300m out toward the mountain, the elevation is 200ft (~60m) higher than my takeoff point, so there I can increase my altitude by 60m to 180m. If I fly an additional 200m out, the terrain is another 60m higher. And so on.

I noticed at another area that I fly there is a mountain that I can use to gain elevation also.

What do you folks do in this situation? Is there an better/easier way to determine this and map it out?

I tried looking at a sectional chart but they are SO busy with airport data and such that it is near impossible to determine specific elevation changes in a small area.
 
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If I understand what you're doing, I think you've got it. A map that shows terrain elevations would the helpful one.

Since we can fly 400' (121M) AGL, you can fly your drone out and follow the terrain and still be at legal altitude. The difficulty is that the drone measures altitude above Home Point, not actual MSL altitude. Example: Home Point altitude is 100' MSL. The drone starts at 0' AGL since that's where it's taking off from. If you fly upward to 300' AGL then fly toward something that is higher, you can increase your altitude, but there's no way to know exact AGL altitude since the drone doesn't measure where you are now, only how high you are above home point. If you have your settings for max altitude @ 400', if you fly higher to follow the terrain, you'd get a warning you are exceeding maximum altitude. BUT you're not really.
 
You can use CalTopo (app or website) to display a topographic map. Then just put the cursor on a point to see it's elevation (and coordinates) displayed at the upper right corner of the map window. See the screenshot.

There are number of topo map apps but CalTopo suits my needs.
 

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If I understand what you're doing, I think you've got it. A map that shows terrain elevations would the helpful one.

Since we can fly 400' (121M) AGL, you can fly your drone out and follow the terrain and still be at legal altitude. The difficulty is that the drone measures altitude above Home Point, not actual MSL altitude. Example: Home Point altitude is 100' MSL. The drone starts at 0' AGL since that's where it's taking off from. If you fly upward to 300' AGL then fly toward something that is higher, you can increase your altitude, but there's no way to know exact AGL altitude since the drone doesn't measure where you are now, only how high you are above home point. If you have your settings for max altitude @ 400', if you fly higher to follow the terrain, you'd get a warning you are exceeding maximum altitude. BUT you're not really.
Yes, that's it exactly...I am trying to maintain 400 ft AGL but the drone only shows altitude relative to the home point, aka takeoff point.
 
You can use CalTopo (app or website) to display a topographic map. Then just put the cursor on a point to see it's elevation (and coordinates) displayed at the upper right corner of the map window. See the screenshot.

There are number of topo map apps but CalTopo suits my needs.

I will check this out...thanks!!
 
I use Google maps with the Terrain layer enabled. It has elevations every 40 feet or so - sometimes 80. Major lines every 200 or so. When I start a flight I set the max altitude to about 200' above the object I am flying. DJI still complains (warns) as I pass 400' above launch. But because I am following terrain as I climb, I'm never above 400AGL. It's a common sense approach - but as long as you are aware of the drones AGL position you should be fine. Where is can get dicey is in emergency RTH - the drone can do some silly things when it gets disconnected from the controller, so read up on those situations so you are prepared to hike a good distance up significant terrain, lose the drone, or just hope it finds it's way home via some good Samaritan that hikes up in that area sometime later.

I've also used GAIA map tools. You can view and download a variety of topo maps to your device for use well beyond cell phone range.
 
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Litchi has a mode that will support waypoint flights that will follow the actual terrain at a programmed flight height. It tracks only ground height, not trees, buildings etc.

It requires you to map your flight from a particular takeoff point in Mission hub, and then actually takeoff from that same spot when you fly the mission.
 
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I tried looking at a sectional chart but they are SO busy with airport data and such that it is near impossible to determine specific elevation changes in a small area.
I'll just take this opportunity to point out that most small human-carrying aircraft will be using a sectional chart as they fly over us at a hundred knots or so. As you point out, a sectional isn't a good substitute for a proper topo map. Like us, they don't have a good easy way to determine their precise height AGL. They may make errors, and they're most likely to intrude into our altitudes near high points such as ridgetops. The most dangerous situation is when we fly while standing on one side of the ridge, and they approach a little low from the opposite side. We may not hear or see them until it's too late.

We always have to give way to them, whether they are there legally or not.

Be careful.
 
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Lots of great info here...thanks! I downloaded CalTopo and the maps are very easy to read and you can measure as well. That gives me something that's workable in the field which is nice!

I'll just take this opportunity to point out that most small human-carrying aircraft will be using a sectional chart as they fly over us at a hundred knots or so. As you point out, a sectional isn't a good substitute for a proper topo map. Like us, they don't have a good easy way to determine their precise height AGL. They may make errors, and they're most likely to intrude into our altitudes near high points such as ridgetops. The most dangerous situation is when we fly while standing on one side of the ridge, and they approach a little low from the opposite side. We may not hear or see them until it's too late.

We always have to give way to them, whether they are there legally or not.

Be careful.

Very good points which I had considered. At least for the mountain behind my house, the peak that I'm flying on top of is not the highest one, though I'm still mindful that my drone is more exposed than usual to the surrounding airspace.

Because of the potential RTH issues, I'm am being conservative regarding the signal strength.
 
The view by going up the mountain behind my house is simply amazing. Here I'm 400ft. AGL from a point on the mountain that is 400ft. above my homepoint, so 800 ft. up! Now I understand how perfectly legal shots can give the impression that the height rules are being broken.

It's fun to explore this type of flying.DJI_0627.JPGDJI_0621.JPG
 
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