"ATTI" Flight Mode -- What Is it; When Is it Forced?

[jclarkw]

I have a new Mavic Air 2, but I'm located inside the Washington, DC, Metro-Area no-drone zone within 15 mi. of Regan National Airport. I want to try out the drone at home before driving to a remote area to play with it. I was hoping to do some test flights inside my house, where the drone probably will not find a GPS location. Before doing so, I was warned on the DJI forum as follows:

"...most often, you will not receive any GPS signal inside the average house, in which case the aircraft will fly in what is called ATTI mode, where it is under full manual flight control. It is a tricky thing to master ATTI mode, and you can very easily fly into walls and other obstacles."

The only thing the user manual says about ATTI mode is the following, which does not suggest the above extreme result:

"The aircraft automatically changes to Attitude (ATTI) mode when the Vision Systems are unavailable or disabled and where the GPS signal is weak or the compass experiences interference [emphasis mine]. In ATTI mode, the aircraft may be more easily affected by its surroundings. Environmental factors such as wind can result in horizontal shifting, which may present hazards, especially when flying in confined spaces."

I'm not an experienced enough pilot to avoid crashing a drone that does not have flight stabilization or collision avoidance -- one of the reasons I bought the Mavic Air 2. I haven't been able to get a straight answer on this from DJI Tech Support. Is it really true that loss of GPS will cause these features to shut down, even if there are sufficient cues for the optical and IR sensors to operate? -- jclarkw

 

[Deleted member 103366]

In a house it is likely you have insufficent locks on GPS satellites to use them for position control ....BUT..... the drone can/does also use a downward looking visual sensor system (VPS?) to hold position both vertically and laterally PROVIDING there is sufficiant light available.
If there is insufficient light for the sensor system to work AND the drone does not see sufficient GPS satellites then it is in full ATTI mode and 'needs' a skilful pilot ( I am not one of those).
Indoors with no GPS but sufficient light both my Mavic Mini and my M2P are inch perfect using just the visual sensor system, I could if I had enough guts fly them through domestic size doorways.
In fact the upward looking obstacle sensor of the M2P is a pain in the derrier indoors, it sees the ceiling all too often, like wise the obstacle avoidance MUST be off otherwise it is impossible to move the M2P through the air.

I would venture that downward looking sensor system offers better position control then GPS.

P16 of the v1.2 manual "The Downward Vision System and Infrared Sensing System helps the aircraft maintain its current position, hover in place more precisely, and to fly indoors or in other environments where GPS is unavailable"

So...... if your house is well lit then I think you can fly without fear indoors but stay away from walls etc. as the drone's own prop wash can, when in close proximity to walls etc., cause a bit of drift

JUST MOVE SLOWLY i.e. use small stick movements

 

[slup]

...I'm not an experienced enough pilot to avoid crashing a drone that does not have flight stabilization or collision avoidance...

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Have seen way too many cases here at the forum where they start up indoors as soon as the first battery is charged ... & then wreck everything up including the brand new drone.

Do yourself as a newbie & your home a big favor ... chill down instead, read up in the full downloadable user manual ... then go to a big open place & slowly test out all functionality.

 

[DanMan32]

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Have seen way too many cases here at the forum where they start up indoors as soon as the first battery is charged ... & then wreck everything up including the brand new drone.

Do yourself as a newbie & your home a big favor ... chill down instead, read up in the full downloadable user manual ... then go to a big open place & slowly test out all functionality.

But that's just it. His big open outdoor space is a big open restricted NFZ.

I'd say a parking garage would be spacious enough and covered so no FAA issues there but likely GPS will still get through and ground the AC.

I understand the need for air security but locking up residential and business for 15 to 30 miles around from any flying is a bit much. There has to be a better solution.

 

[Deleted member 103366]

@slup, lol, that guy's nuts.
Picking up a running, crashed Phantom is asking for unanaesthetized surgery, the props can leave wonderful cuts on a bare arm. I can't help but wonder how much force he had to use on that leg to control a 'trying to recover' Phantom.
Having flown the MM etc. indoors, if I now fly my P3 indoors I rarely let go of the P3's leg so a 'flight' is more of an anchored hover etc. or yaw around the anchored leg rather than a free flight.

For the OP, the video raises another point, whilst going through the manual do please take notice of how you can 'stop' the motors in an emergency. (CSC maneuver)
There are a number of posts on this forum concerning the procedure and its various options

 

[Meta4]

I haven't been able to get a straight answer on this from DJI Tech Support. Is it really true that loss of GPS will cause these features to shut down, even if there are sufficient cues for the optical and IR sensors to operate?

It's not a case of the drone "switching" to atti mode on loss of GPS (and unsuitable conditions for VPS).
It's more a case of atti mode is what's left when GPS and VPS are gone.
In atti mode, there is no horizontal position holding and the drone has no "brakes" and will continue to "skid" when you take your hands off the sticks.
It's like driving on ice without brakes.
Obstacle avoidance cannot work without horizontal position holding.

 

[jclarkw]

...In atti mode, there is no horizontal position holding and the drone has no "brakes" and will continue to "skid" when you take your hands off the sticks.
It's like driving on ice without brakes...

Meta4 -- Yeah, I understand what that's like from flying my little Parrot Mambo with stabilization turned off. I don't what to go there with the new Mavic Air 2, which is why that first quote in my OP alarmed me.

Apparently the correct answer is that quote is wrong, and horizontal position holding and collision avoidance will continue to operate without GPS (given sufficient light).

Agreed? -- jclarkw

 

[Meta4]

(given sufficient light).

Agreed? -- jclarkw

It also requires a suitable ground surface texture.
It won't work on a surface without distinguishable features.

 

[slup]

...horizontal position holding and collision avoidance will continue to operate without GPS (given sufficient light).

Yeah, sufficient light (& surface) ... you got it ... but suddenly you don't.

 

[hiflyer201]

So...... if your house is well lit then I think you can fly without fear indoors but stay away from walls etc. as the drone's own prop wash can, when in close proximity to walls etc., cause a bit of drift

Turn off all ceiling fans. Spackle comes in tubes now and props are fairly cheap....on second thought..drive the fifteen miles. After the first flight you will better know what to expect and you'll have the confidence to fly safely in the house.

 

[CareyL]

Put on prop guards. Atti = Attitude and the drome will hold a steady height when you lift it off the ground. If you give it forward/backward or sideways propulsion it will continue to drift in that direction until you apply an opposite force.

When I first got a Mavic Mini I flew it from my basement to the top floor of my 3 level townhome, through doorways and up the stairs, including 180 turns while going up and down.

It can be done if you are desperate. I also put a Firehouse white light in steady on mode on the bottom of the drone.

 

[DanMan32]

Put on prop guards. Atti = Attitude and the drome will hold a steady height when you lift it off the ground. If you give it forward/backward or sideways propulsion it will continue to drift in that direction until you apply an opposite force.

When I first got a Mavic Mini I flew it from my basement to the top floor of my 3 level townhome, through doorways and up the stairs, including 180 turns while going up and down.

It can be done if you are desperate. I also put a Firehouse white light in steady on mode on the bottom of the drone.

No, it won't just keep going. It will slow down and stop, assuming no external influences.

 

[Crouching Leopard]

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Have seen way too many cases here at the forum where they start up indoors as soon as the first battery is charged ... & then wreck everything up including the brand new drone.

Do yourself as a newbie & your home a big favor ... chill down instead, read up in the full downloadable user manual ... then go to a big open place & slowly test out all functionality.

Ahhh. The famous wall suck maneuver. Should only be performed by true expert flyers and house renovators.? Done a couple myself. Really good at wall repair now!

 

[Thomas B]

But that's just it. His big open outdoor space is a big open restricted NFZ.

I'd say a parking garage would be spacious enough and covered so no FAA issues there but likely GPS will still get through and ground the AC.

I understand the need for air security but locking up residential and business for 15 to 30 miles around from any flying is a bit much. There has to be a better solution.

Likely constructed of reinforced concrete... a lot of rebar.... on all sides of the drone... doesn’t sound like a good or safe place to fly.

 

[DanMan32]

Rebar would be a factor in takeoff and landing, but you'd have to be near or at prop interfering crash distance to walls for their rebar to affect it.

You can hand launch/land if rebar in the floor is a problem, or use an elevated surface like a box to launch from.

I've flown my P3 and I think my M2Z without issues in a parking garage.

 

[Thomas B]

Rebar would be a factor in takeoff and landing, but you'd have to be near or at prop interfering crash distance to walls for their rebar to affect it.

You can hand launch/land if rebar in the floor is a problem, or use an elevated surface like a box to launch from.

I've flown my P3 and I think my M2Z without issues in a parking garage.

Rebar is a compass problem at a minimum. Guess you were flying ATTI mode... due to lack of satellites.

 

[jclarkw]

Rebar is a compass problem at a minimum. Guess you were flying ATTI mode... due to lack of satellites.

Wait! What does rebar have to do with anything (except the compass)? And what does the compass have to do with flight close to the "ground," which should be stabilized by the "Downward Vision System?"

Note that the user manual says, "It is not necessary to calibrate the compass when flying indoors." -- jclarkw

 

[jclarkw]

In agreement with what many have said in this thread (except for my still-open question about the compass), I finally got an unambiguous answer from DJI email tech support as follows:

"1. Stabilization system relis on GPS signal and visual system, as long as one of them two is working, the drone can hover stably [emphasis mine]. The hovering accuracy range is vary, depends one whether GPS system or visual system works.

"2. Most customer type drone has stabilization system. In order to maintain the stability of the aircraft, the main control system will correct the motor operation according to your operation and the current environment. So Mavic Air can’t achieve ”full manual control” function [emphasis mine] you mentioned."

Accordingly I will try this out as soon as my propeller protectors arrive from DJI and report... -- jclarkw

 

[jclarkw]

Well, that was a bust! I cannot find anywhere in the house (except an interior hall on the bottom floor which is too narrow to fly) where the Mavic Air 2 doesn't know it's in a restricted zone. It must have a really good GPS receiver onboard. (It's not using my cell phone because I turned off all location services and put it in airplane mode.)

Speculating that the GPS antenna(s) may use the prop arms in addition to the A/C body, I doubt it's possible to shield it(them). Does anyone know anything about this?

 

[Meta4]

Wait! What does rebar have to do with anything (except the compass)? And what does the compass have to do with flight close to the "ground," which should be stabilized by the "Downward Vision System?"

Launching from reinforced concrete surfaces can cause big problems and the compass is critical for all flight.
The explanation is a little complicated .. see this post:

Avoiding the rebar effect

I would like to make my takeoff and home point on a concrete portion of my driveway. Thinking of using a wooden table to distance my takeoff point from the rebar underneath. How tall should the table be? .... or is this just a wish that should not be pursued at all .... and why?

phantompilots.com

Note that the user manual says, "It is not necessary to calibrate the compass when flying indoors."

It's almost never necessary to recalibrate the compass.
But recalibrating the compass doesn't "fix" anything, particularly when the thing that needs fixing is the launch environment rather than the drone..