Hovering question....... please dont laugh

[W2EJ]

Similar kind of question if I may... if I take off and hover at say 50ft.. and then fly over a quarry where the quarry floor is 400ft below... what happens to the drone? I have a Mavic Air. Does the height of the drone then become 450ft.. and now flying higher than permitted?!

No. The drone only knows it's height above the takeoff point. It doesn't have a radar altimeter.

 

[W2EJ]

I wonder how surprised this guy was to cuddle up with his Phantom that night!

That was unbelievable! Very exciting and a great video! Super skill required as well.

 

[billfoggon69]

Set dynamic home point to the remote... of course you’d have to have your phone attached with the GPS running. The RTH command should cause the drone to come back and attempt to land where the remote is, or at least near it.

Nice theoretical question, but no cruise line I know allows drone flights from the ship.

Be careful guys. Setting return to home only comes back to the controller exactly where you set the RTH for the controller. Once the controller moves its position, the drone will NOT follow it to its new position. I only found this out by accident and it didn't cause much bother as I was only about 50 metres away but if you are on water its a disaster.

 

[Manicha]

VPS might let it track the cruise ship deck in place of GPS.
If it wasn't for VPS, it would slip to the back of the ship at 20mph based on GPS unless you countered with forward thrust.

My two cents worth, tried to fly off of one of those large private Catamaran cruise boats you go off with 60 people.
Asked permission when it was anchored and most occupants were snorkeling. The Mavic Air wouldn’t even work.... magnetic and compass error came on the screen and it never could go to green/ Ready for flight. Imagine if it had intermittent errors and I could get it off then try to bring it back to land with compass/ errors activating. You would lose positioning and all that interference might not be able to retrieve specially losing GPS mode in the mix and no doubt some wind to deal with!
Sounds like a nightmare/ loose Ac would be what would happen. Glad compass and Magnetic interference came up and never let me take off or I may not of gotten it back on the boat!

 

[FoxhallGH]

Set dynamic home point to the remote... of course you’d have to have your phone attached with the GPS running. The RTH command should cause the drone to come back and attempt to land where the remote is, or at least near it.

Nice theoretical question, but no cruise line I know allows drone flights from the ship.

This Dynamic Home point thing comes up every now and again ... If you set your home point to be the controller - then move (or be moved in/on a vehicle), then yes - the home point will dynamically move with you. BUT - the problem comes when that home point is used in RTH ... The Controller will advise you that the home point has changed from where it was when you started, and ask you if you want to use the current location - which you would! However, if you confirm that, the Mavic will use that 'static' location point to RTH to ... In other words, if you are still proceeding on - it will be left behind! You would have to stop the boat to get the RTH to return the Mavic to you.

 

[FoxhallGH]

Similar kind of question if I may... if I take off and hover at say 50ft.. and then fly over a quarry where the quarry floor is 400ft below... what happens to the drone? I have a Mavic Air. Does the height of the drone then become 450ft.. and now flying higher than permitted?!

I believe that the answer is in a diagram like this ...

The 400 ft rule follows the terrain, it's not a vertical line. Depending on the country, and depending on if you are PfCO / part 107 - the rules may be different - but my understanding was that if you were to go out over your 400 ft cliff, you can move 400 ft horizontally from the cliff face before you are in violation of the 400 ft rule. This is similar to flying e.g. a 400 ft tower. You could rise to a height of 800 ft, as long as you were within a radius of 400 ft from the tower.

 

[Snowstorm]

That was unbelievable! Very exciting and a great video! Super skill required as well.

Ok, it can be done. But you got to be like them.

 

[radmanzulu]

I’ve tried this from a Danube River cruiser and it ended badly. Unless you hand launch it from the rear of the vessel, anything that is higher than the drone during take off will keep moving forward as part of the vessel while the drone remains stationary. To the observer, it will look like the drone took off and flew backwards immediately crashing into whatever is aft of it. This unfortunate accident cost me one of my pre-paid returns to DJI to repair two broken arms.

 

[Tic Toc]

I’m sitting on the fantail of a cruiseship which is underway....... aprox 20mph
I launch and hover my drone at ....... say 50 feet.
Will the drone be left hovering in place as the cruiseship moves away OR will it stay in place ......... hovering over me and the fantail

You can’t fly a drone on a cruise ship

 

[Drgnfli]

That would be tracking, but I'm kind of wondering more about the obstacle avoidance aspect. Would the drone actively avoid an object coming at it at 20 mph? I'm also now wondering about landing. How would the drone handle landing at 20 mph. It would be leaning forward to keep it's speed up, but it would be approaching the ground which it would calculate to be moving past it at 20 mph. Assuming it would actually touch down with a 20mph airspeed what would happen when it transitioned from flying to the ground since the blades are spinning quite fast to keep the forward speed.

You should try all of this while boating on a small, private pleasure boat in the 15 to 30-foot class. Not unless you want to break or lose your AC... IMHO!

 

[Drgnfli]

How does it “know” what it’s height is when it takes off? GPS?

Anyone actually have real life experience flying off a cliff?

Why doesn’t it update it’s altitude when the terrain changes?

I live in AZ - flown off many, many cliffs to photo the canyons & riparian areas below. My Mavic Pro shows the height of the takeoff point which is zero. When I drop into a canyon, it will go into the negative numbers (-10, -50, -150, -400, etc). I would like it to know what the correct altitude is above the ground or trees but don't know how to see that number if it is even available. Looking down on your drone makes it very hairy & impossible to estimate how high you are above the ground let alone the trees you are nearing. The good thing is if you must hit the RTH button, my drone will climb to that number before it heads home so you won't be crashing into a canyon wall. With all the techy stuff that DJI does, you'd think they could show you the correct altitude you are above the ground you are flying over...

 

[Meta4]

With all the techy stuff that DJI does, you'd think they could show you the correct altitude you are above the ground you are flying over...

If you flew a small general aviation aircraft and wanted to check your AGL altitude, here's one of your cheapeast and lightest options:
GRA™ 55
It's US$6300 and weighs 3.5 lbs just for the bare instrument, which is why most small aircraft pilots have to estimate their AGL height just like you..

 

[EGS]

It is an interesting question that at some point many of us wonder what would or could happen.
Some experiments have been done by others to figure out exactly what would happen.
Here is a link to a YouTube video done by Ken Heron, maybe that will give you a better idea of what could happen if such a thing is attempted.

 

[Prmath]

You can’t fly a drone on a cruise ship

OK, let’s say on a flatbed truck.......

 

[Prmath]

Sorry for all the ballAche....I just wondered ...... What If ? That’s all

 

[JDawg]

Sorry for all the ballAche....I just wondered ...... What If ? That’s all

LMAO. I knew it!

 

[Flynz]

OK, now I'm curious about the opposite end of the ship. Since the drone will stay stationery based on GPS, what will happen if you take off from the front of the ship? I assume the drone will stay still, but will the sensors do anything to try to prevent the superstructure of the ship from running into it?

SMASH!

 

[Flynz]

A lot of times cruise ships speeds are reduced in order to save money and to arrive at port according to schedule. I’ve seen 10-12 mph speeds on my GPS many times. I thought about asking if I could do a late night/early morning flight when no one is on deck. A cruise ship sailing on a clear night with a full moon and a port of call in the background would be cool video! I do a Panama Cruise this Spring.

Don’t forget the wind. The drone will experience the effective airspeed which is the ship speed plus the wind vector. Might need sports mode.

 

[Flynz]

I have experienced this situation myself. The boat was a 20 meters cruising boat and sailing no faster than 12 kts. The tallest part of the boat was only 6 meters over the deck where I was. I launched my Mavic Pro from the bow of the boat and suddenly she was flying to me (@ 12 kts, I guess), I avoided and collided with the cockpit. Fortunately, the drone flipped after the collision and ended up capsized on the deck. Only two props broken.

Nice story!

I changed the damaged propellers, I went to the stern of the boat to try it again. This time I position myself in a safe place, the Mavic took off and remained hovering, though the feeling was like the Mavic was flying away at high speed. I have to say that the Mavic was hovering in the place where she took off and was over the boat no more than two seconds.

After testing some Active Track modes was time to land. Forget about hand catch: it's too dangerous for your friends finger; not yours because you'll be very busy with the remote. At the end, I landed by crashing the drone over some mattresses I distributed on the deck.

The conclusion is, as WithTheBirds says, the Mavic doesn't know she was launched from a moving vessel and she was happily hover in position, but I was not. To land you have to fly at the speed of the boat plus the wind you have in that moment, which is not an easy manoeuvre. It was an exciting experience but too dangerous for the people around and with a high risk of end up with the drone in the bottom of the sea.

 

[Flynz]

That was unbelievable! Very exciting and a great video! Super skill required as well.

And they caught it!