Greetings all. Noob Steve here. Hope you'll be gentle. If you take off from the top of a 700 foot cliff, and fly out over the 700 foot drop-off, will your phantom maintain altitude, or will it descend because of the 400 ft. forced ceiling? I don't have my phantom yet, but just trying to learn all I can before I get it, and get in the air. I may be misinterpreting the 'forced ceiling' thing. Thanks in advance.
Mountain or gorge flying and 400 ft. ceiling question
- Thread starter mmpsteve
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The 400 metres only starts at take off I believe
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I'm a newb too, so I am not sure, but I thought the 400' was barometric above sea level so I am not sure you will be able to take off at all from 700'.
HighTech, it's not above sea level. If you look on YouTube, you see all kinds of stunning videos of people in the mountains, on top of mountains, off cliffs, etc.... , so I'm thinking my question may sound silly to the experienced people here. But I thought the DJI software would limit you to 400 feet above ground level (takeoff level).
I believe it is 400 feet relative to the start point. Which brings up a question, if you go out over the cliff and now are 800 feet above the ground, are you violating the FAA rules?
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I think you can disable the 400' foot ceiling limit and assumed that's the setup on drones above 400' from sea level. Thank goodness an actual expert will probably respond and we will both learn the specifics on this.
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The rule is 400 feet above the ground. It's easier to view that from the home point, but you could technically climb a thousand foot incline so long as you remained less than 400 feet above the ground the whole time.
In truth, there are exceptions to just about all the rules, but for newbies it's best to stay within the more limiting framework.
Brian
In truth, there are exceptions to just about all the rules, but for newbies it's best to stay within the more limiting framework.
Brian
Meta4
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There is no "forced ceiling" but there is a user configurable max height limit.
WIth this switched off, you can go up to 500 metres above launch point.
Your Phantom won't fall if you fly off a cliff as all heights are relative to the home point - and the Phantom has no way of knowing what is below it anyway.
alokbhargava
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Your home point is taken as reference I.e. Zero level. All other limits are related to it. For example, if you set altitude limit as 120 m, you can fly upto 130m above the home point.
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Thanks everyone. I was thinking the bottom sensors would calculate height, and keep you from getting back to homepoint, if you flew out over a shear cliff. Actually, I live in flat farmland, but have a few trips planned in more scenic terrain. I'm blown away by the beauty shown in a lot of the videos posted here and on youtube. Thanks again.
As mentioned, your altitude as seen by the Phantom and app is from the take off point. Go up 10' and over a 500' cliff and it will still register 10'. It will also stay at that same altitude no matter what rises or drops you fly over. 400' above ground level is a recommendation by the FAA, not a regulation (for hobby use)
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I see multiple post in multiple threads of people saying 400m (meters) when they mean 400 feet. (120m) Huge difference! Please learn the difference before trying to help someone!
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There is a huge difference between AGL, which is above ground level, and MSL, which is above mean sea level. The remote controller reports height above take-off point, which is something else again (e.g., it is more like TL, or takeoff level). So to answer your question, if you take off from a 700 foot MSL cliff, climb 100 feet (e.g., 100 AGL and 900 MSL), and fly over the cliff your drone will think it is still at 100 AGL (actually 100 ATL), even though at that point you are quite high above ground level.
I have the reverse problem. I routinely takeoff at 800 MSL, and then fly over a hill. The hill is shown on maps as a peak at 1100 MSL, which is 300 feet above my take-off point. If I rise to 400 ATL, then fly level over the hill at its peak I will be at 100 AGL, 1200 MSL, while my remote controller will report 400 feet.
Hope that makes sense.
I have the reverse problem. I routinely takeoff at 800 MSL, and then fly over a hill. The hill is shown on maps as a peak at 1100 MSL, which is 300 feet above my take-off point. If I rise to 400 ATL, then fly level over the hill at its peak I will be at 100 AGL, 1200 MSL, while my remote controller will report 400 feet.
Hope that makes sense.
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I was always wondering what happens if your home point is set and you fly over a cliff and drop down say 300 feet. What happens if RTH kicks in? Will it crash into the cliff or will it climb back up to the original home point and then the additional feet set in RTH?
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400' elevation limit is meant as 400' ABOVE GROUND LEVEL (AGL). Above ground means exactly that, the elevation of the drone to the ground at any point during its flight. This has nothing to do with takeoff elevation (home point) unless you fly in a very large totally flat area.
There are some interesting special cases to that (maybe open for interpretation or discussion). Let's say you fly over the top of a mountain that has a vertical rock wall on the other side that is let's say 2000' tall. As you fly over, at that point the drone will be over 2000' above ground level. Is that a problem? Well, that is where the discussion may come in: The FAA setup this rule to match the manned airplane flight restrictions which I believe do not allow a plane to fly lower than 500' above ground or CLOSER THAN 500' to a mountain side (in our example the vertical wall). In order to avoid collisions, the drone must simply stay within a 400' distance of that wall as long as it is over 400' above ground level.
I just recently flew a mountain video mission that took the P3P over 1630' above the home point, yet the flight path stayed within FAA recommendations throughout the flight path.
I believe that this depends on what you are flying and how it is programmed. The Phantom 4 Pro has a complex array of collision avoidance sensors that come into play during RTH. The DJI Go 4 app further lets you specify how high your drone should climb in a RTH (Return-to-Home altitude on the Main Controller Settings screen). Your assignment is to read the User Manual, pp.15-19, paying close attention to the differences between Smart RTH, Low Battery RTH, and Failsafe RTH, and closely parsing the section on Obstacle Avoidance During RTH, and report back to us. Be sure to turn on RTH Obstacle Check in the flight app (Advanced Settings).
Yes, I did teach school in a prior life.
Thanks again everyone. It's pretty clear now. I mistakenly thought the DJI firmware would prevent you from climbing higher than 400 feet (USA). " Your assignment is to read the User Manual" I've got much homework to do, indeed. Good thing I don't have the P4P yet; that, and it's -12 degrees here this morning.
