Setting Altitude in RTH

[Crash and Burn]

My SE arrived Monday but the weather hasn't been great and I feel like I have so much to learn before taking off. We live in a valley in rainforest mountain range, I think the safest place to take off from would be from a roadway on a hill rather than the flats. That way I'm above trees, bamboos, buildings, etc and should get better gps signal. If I'm setting my RTH signal will it being using the altitude I launch from rather than where it will be flying over? What are the safe RTH setting in this situation? I've read somewhere cinematic can be a bit dodgy with a weak GPS. How can I make the most out of (and safest way to fly) what I anticipate to be an unreliable gps signal (I say this based on me having to climb the hill to update my garmin inreach mini to update)? Any other tips to minimize stupid pilot errors? I've literally never used a joystick before and am not the most spatially well oriented person in the world. Thanks!

 

[Meta4]

If I'm setting my RTH signal will it being using the altitude I launch from rather than where it will be flying over? What are the safe RTH setting in this situation?

All heights (including RTH height) are relative to the home point.
Home = zero.
The drone has no way to know what it is flying over.

I've read somewhere cinematic can be a bit dodgy with a weak GPS

Any flight mode could be dodgy without GPS.
Without GPS, you lose horizontal position holding.

How can I make the most out of (and safest way to fly) what I anticipate to be an unreliable gps signal (I say this based on me having to climb the hill to update my garmin inreach mini to update)?

Don't fly where terrain or tree cover blocks the GPS receiver's skyview.

Any other tips to minimize stupid pilot errors? I've literally never used a joystick before and am not the most spatially well oriented person in the world.

Do your early flying in a large, open area, well away from trees, buildings and other obstacles.
If there's nothing to run into, it's hard to get into trouble.

 

[CalOldBlue]

Do your early flying in a large, open area, well away from trees, buildings and other obstacles.
If there's nothing to run into, it's hard to get into trouble.

I did some practice quite recently on a large open field holding three baseball fields in three of the corners.

Almost no people; great for practicing: as for getting into trouble... I won't be going back, as the last time I was there a guy got shot in the parking lot 100 yards away from me.

 

[MAvic_South_Oz]

I've literally never used a joystick before and am not the most spatially well oriented person in the world.

As meta4 said, just practice a lot first in a safe flat open space.
You need to take time to get used to those sticks, YouTube first flight tutorial exercises etc, and of course the many other drone functions available to you.
If it's not possible, the risk of possible problems escalates dramatically.

As for RTH height setting.
Before every single flight, you should do this automatically, after getting used to doing it as routinely.

If I'm flying from a high point, be it a cliff on the coast out over the sea, or a hillside carpark flying out over a valley, I set RTH altitude to say 5m, or whatever is immediately around me tree wise etc . . . it's all you need.
If set higher, it serves no purpose but to send the drone into potentially higher winds, should it RTH low battery or failsafe.
Of course you can control RTH alt by bringing the drone down manually, it's just another thing to do if no set right, in the middle of watching other telemetry for safe flight back.

I rarely use RTH for auto flying back to base, and almost NEVER let it go to low battery RTH . . . failsafe loss of signal RTH is the only other thing that can happen, but best to simply plan flights well and minimise the risk of that happening . . .
No flying under canopy (unless failsafe set to hover), no distance without altitude to keep signal clear and away from tree foliage, terrain, etc, and kept reasonably close, even if flying way out over the ocean at low altitude.

I don't want to alarm you too much though, just practice setting that before a flight, the drones are very stable and it's probable you won't have any issues, just get your GPS lock (HP recorded), stay in clear LOS for signal to the drone, and enjoy flying for a while . . . photos and video can come later after you are used to getting from airborne to landed all ok.

 

[Crash and Burn]

As meta4 said, just practice a lot first in a safe flat open space.
You need to take time to get used to those sticks, YouTube first flight tutorial exercises etc, and of course the many other drone functions available to you.
If it's not possible, the risk of possible problems escalates dramatically.

As for RTH height setting.
Before every single flight, you should do this automatically, after getting used to doing it as routinely.

If I'm flying from a high point, be it a cliff on the coast out over the sea, or a hillside carpark flying out over a valley, I set RTH altitude to say 5m, or whatever is immediately around me tree wise etc . . . it's all you need.
If set higher, it serves no purpose but to send the drone into potentially higher winds, should it RTH low battery or failsafe.
Of course you can control RTH alt by bringing the drone down manually, it's just another thing to do if no set right, in the middle of watching other telemetry for safe flight back.

I rarely use RTH for auto flying back to base, and almost NEVER let it go to low battery RTH . . . failsafe loss of signal RTH is the only other thing that can happen, but best to simply plan flights well and minimise the risk of that happening . . .
No flying under canopy (unless failsafe set to hover), no distance without altitude to keep signal clear and away from tree foliage, terrain, etc, and kept reasonably close, even if flying way out over the ocean at low altitude.

I don't want to alarm you too much though, just practice setting that before a flight, the drones are very stable and it's probable you won't have any issues, just get your GPS lock (HP recorded), stay in clear LOS for signal to the drone, and enjoy flying for a while . . . photos and video can come later after you are used to getting from airborne to landed all ok.

Thank you for the very detailed sound advice.

 

[umanbean]

How can I make the most out of (and safest way to fly) what I anticipate to be an unreliable gps signal

I wouldn't fly with 'an unreliable gps signal'... period.

Launch with VPS turned ON and ascend straight up to above treetop level for a minute, then it'll get a better sat lock, and home point will be directly below - where you launched from. That way, RTH will be accurate and reliable. You should be able to see 'GPS health' icon on the main screen.

 

[Crash and Burn]

I wouldn't fly with 'an unreliable gps signal'... period.

I don't know and can't be sure how close or how much interference or what structure will cause it and certainly won't have the ability to apply hindsight. Chances are at some point I'm going to encounter a poor gps signal. I was hoping there were actions I could take to avoid tragedy or advice on what to do if I did lose signal but thanks anyway.

 

[umanbean]

Thanks anyway?

As long as your SE starts with a clear sky view before it sets HP and you ascend to alt you want to fly at, you should have no problems.

Please see posts #2, #4, and my #6... re-read them if you need to.

 

[umanbean]

I was hoping there were actions I could take to avoid tragedy or advice on what to do if I did lose signal but thanks anyway.

Learn how to fly in ATTI mode, and maintain VLOS at all times

 

[Meta4]

I don't know and can't be sure how close or how much interference or what structure will cause it and certainly won't have the ability to apply hindsight. Chances are at some point I'm going to encounter a poor gps signal. I was hoping there were actions I could take to avoid tragedy or advice on what to do if I did lose signal but thanks anyway.

The world runs on GPS, it's very reliable and stable.
There is no such thing as a poor GPS signal.
To avoid losing GPS, you just have to avoid blocking the drone's view of the sky with things that the GPS signal can't pass through.
That's metal roofs, mountains and water (trees are full of water).
Otherwise you've no reason to fear losing GPS.
In more than 6000 kilometres of flying, I've never lost GPS signal.

 

[Meta4]

Chances are at some point I'm going to encounter a poor gps signal. I was hoping there were actions I could take to avoid tragedy or advice on what to do if I did lose signal but thanks anyway.

In the unlikely case of losing GPS, your drone is still completely controllable.
It will still maintain height, but will have lost horizontal position holding.
That means it can drift if left in any wind, and it won't have any "brakes".

If you lose control signal, that will initiate Failsafe RTH to bring your drone home.

 

[umanbean]

If you lose control signal, that will initiate Failsafe RTH to bring your drone home.

As long as you ALWAYS make sure the HP is set correctly before flying off into the wild blue yonder.

 

[Crash and Burn]

Learn how to fly in ATTI mode, and maintain VLOS at all times

VLOS absolutely, ATTI mode scary ?

 

[Crash and Burn]

In the unlikely case of losing GPS, your drone is still completely controllable.
It will still maintain height, but will have lost horizontal position holding.
That means it can drift if left in any wind, and it won't have any "brakes".

If you lose control signal, that will initiate Failsafe RTH to bring your drone home.

Point taken on the difference between signal loss and poor reception.

Thank you for explaining ATTI mode. I'll do a little more research on flying without horizontal position holding.

 

[Zbip57]

We live in a valley in rainforest mountain range, I think the safest place to take off from would be from a roadway on a hill rather than the flats. That way I'm above trees, bamboos, buildings, etc and should get better gps signal.

Two things to watch out for. As long as the drone is above the trees and building etc, it will have a better view of the sky and thus get better GPS reception. That's good.

But, if you and your controller are still below the tree and buildings they might be blocking your control signal between the transmitter and the drone thereby limiting your range. That's maybe not so good.

If I'm setting my RTH signal will it being using the altitude I launch from rather than where it will be flying over? What are the safe RTH setting in this situation?

The drone's height is always measured by the barometric altimeter relative to its takeoff location (zero height). Take off, climb straight up, rotate 360° and check the camera view. If you have a clear view over the treetops, set your RTH height to a safe margin higher than that.

I've read somewhere cinematic can be a bit dodgy with a weak GPS.

You can still fly without GPS lock. It's really only used for position hold when the control sticks are released on centre. With GPS, when the sticks are centred, the drone will brake to a halt and hover holding that fixed position. Without GPS, and without Visual Positioning System (VPS), the drone will switch to ATTI mode. It will still maintain height using its barometric altimeter, but it will not brake to a halt whenever sticks are centred but will continue drifting. You then just need to apply stick pressure in the opposite direction to force it to slow down. It won't hold a fixed position in hover though, instead it will drift freely with any wind. You just need to input stick control to force it to go where you want.

I don't know and can't be sure how close or how much interference or what structure will cause it and certainly won't have the ability to apply hindsight. Chances are at some point I'm going to encounter a poor gps signal.

It's more serious when those two things going wrong at the same time.

As long as the drone has sufficient GPS reception, if a structure or heavy tree cover interrupts your transmitter's control signal, then the drone will automatically return to home all by itself. All good.

Or, if the drone loses GPS reception, as long as you still have a solid control signal, the drone is perfectly controllable in ATTI mode without GPS as long as you continue to give the proper stick inputs.

But, if the drone loses GPS reception, AND structures or heavy tree cover simultaneously block your control signal, then the drone will be unable to automatically navigate its way home. It will instead freely drift away with the wind until eventually auto-landing somewhere due to low battery.

Normally the video signal is interrupted first, while you still have a solid control signal. If you ever lose video reception, the best response is to get the drone to climb higher to clear any obstacles that might be obstructing the signal.

 

[Zbip57]

I made a video a long time ago, using my Phantom-1, to show the difference between GPS-mode and ATTI-mode.

At the time there were a lot of unexplained "fly-aways" with plenty of hair-brained theories on what was causing them. One such theory was that a "GPS glitch" could somehow cause the drone to uncontrollably fly away back to China...

The controller for the original Phantom didn't have a self-centring throttle stick. It was tricky trying to get the stick exactly in the middle in order maintain height in a hover. That's why it's slowly sinking or climbing in this video. Later versions had a spring-loaded throttle stick that automatically centres itself when released.

 

[Crash and Burn]

Two things to watch out for. As long as the drone is above the trees and building etc, it will have a better view of the sky and thus get better GPS reception. That's good.

But, if you and your controller are still below the tree and buildings they might be blocking your control signal between the transmitter and the drone thereby limiting your range. That's maybe not so good.

The drone's height is always measured by the barometric altimeter relative to its takeoff location (zero height). Take off, climb straight up, rotate 360° and check the camera view. If you have a clear view over the treetops, set your RTH height to a safe margin higher than that.


You can still fly without GPS lock. It's really only used for position hold when the control sticks are released on centre. With GPS, when the sticks are centred, the drone will brake to a halt and hover holding that fixed position. Without GPS, and without Visual Positioning System (VPS), the drone will switch to ATTI mode. It will still maintain height using its barometric altimeter, but it will not brake to a halt whenever sticks are centred but will continue drifting. You then just need to apply stick pressure in the opposite direction to force it to slow down. It won't hold a fixed position in hover though, instead it will drift freely with any wind. You just need to input stick control to force it to go where you want.

It's more serious when those two things going wrong at the same time.

As long as the drone has sufficient GPS reception, if a structure or heavy tree cover interrupts your transmitter's control signal, then the drone will automatically return to home all by itself. All good.

Or, if the drone loses GPS reception, as long as you still have a solid control signal, the drone is perfectly controllable in ATTI mode without GPS as long as you continue to give the proper stick inputs.

But, if the drone loses GPS reception, AND structures or heavy tree cover simultaneously block your control signal, then the drone will be unable to automatically navigate its way home. It will instead freely drift away with the wind until eventually auto-landing somewhere due to low battery.

Normally the video signal is interrupted first, while you still have a solid control signal. If you ever lose video reception, the best response is to get the drone to climb higher to clear any obstacles that might be obstructing the signal.

Thank you, the info on the controller being blocked isn't something I had considered before.

I know I should take my time and learn in a field but I live in beautiful jungle clad mountains and I'll be doing a lot of flying around here and eventually from my boat. RTH may be a bit tricky, bringing it up to regain signal sounds like a safer option in my situation.

I'm so glad I got DJI Refresh. Like the saying goes a ship is safest in the harbour but that's not what a ship is for.

Edit: Thanks for linking your video, that was an awesome tutorial!

 

[Zbip57]

I'll be doing a lot of flying around here and eventually from my boat. RTH may be a bit tricky,

If the drone has sufficient GPS reception, the Home Point is recorded at takeoff. If you subsequently move your boat, obviously the Home Point stays behind where ever it was originally recorded.

Here's a very well done tutorial on the various map functions on the DJI Fly app. At 8:30 in this video he explains how to update the Home Point to any chosen new location by dragging it around on the map. i.e. You can drag the Home Point to any conveniently located nearby island or beach.

He should also have mentioned there are two other options. On the map display at 9:00 in the video, in the upper right corner there are two icons, an aircraft or controller icon. Clicking on those lets you update the Home Point to either the aircraft's or the controller's current location. Note: That is the location at that particular moment in time. It will not automatically continue to follow the controller's location. So if you move your boat again, you should periodically update to your controller's current location.

 

[Crash and Burn]

If the drone has sufficient GPS reception, the Home Point is recorded at takeoff. If you subsequently move your boat, obviously the Home Point stays behind where ever it was originally recorded.

Here's a very well done tutorial on the various map functions on the DJI Fly app. At 8:30 in this video he explains how to update the Home Point to any chosen new location by dragging it around on the map. i.e. You can drag the Home Point to any conveniently located nearby island or beach.

He should also have mentioned there are two other options. On the map display at 9:00 in the video, in the upper right corner there are two icons, an aircraft or controller icon. Clicking on those lets you update the Home Point to either the aircraft's or the controller's current location. Note: That is the location at that particular moment in time. It will not automatically continue to follow the controller's location. So if you move your boat again, you should periodically update to your controller's current location.

I've been watching videos but it's not always easy finding the best ones to explain specific things, I appreciate you taking the time to link good ones for me

Not keen on full RTH to land on the boat and it's a bit far off for now, I have a lot to learn before getting there. We use a trolling motor to spot lock but it stays within a couple of feet of gps lock and RTH can be a foot or two off, on a 21 ft boat I think need to be more precise. Updating RTH and then going manual as it gets close sounds like a good option.

First couple of flights and landing will be at a sand cay on the reef and eventually will tackle flying off and landing on the boat.

Uggh, but right now I have to go to work and pay for all this stuff.

 

[MAvic_South_Oz]

Chances are at some point I'm going to encounter a poor gps signal.

At some point maybe, but it would likely only be inside a building, or in the depths of a deep gorge etc, where some overhead sats may be 'visible' to the drones receiver, and more lateral ones might be blocked.

But even inside my home, when checking for updates or playing with settings etc, I usually get good satellite reception and home point recorded.

Outside I have never had a problem getting a sat lock almost before I'm ready to fire up the motors, and never lost GPS once locked in, and you probably won't have any issues either.

VLOS absolutely, ATTI mode scary ?

VLOS is important for staying within CASA rules of course, but to be clear, it's more LOS that will be a possible problem with failsafe RTH being activated, it won't affect GPS function and that side of things.
LOS is similar to VLOS, except of almost all DJI consumer drones LOS is far far further than VLOS.

LOS is related to signal from controller to drone more so.
If nothing between you and the drone, you are facing the drone with antenna orientated properly, you should have great signal and control reliability way out past VLOS, so flying to CASA regs you will never have a problem.

Also staying that close (with strobes maybe up to 1km or so in some places) you avoid interference like trees / foliage, hilly terrain if flying lower down, and if flying behind something briefly you will be less likely to lose that signal for a short period.