Lost my P3A in the drink!

[folp]

Hi all -

I lost my P3A in the Oakland harbor this morning and I don't know why. I was flying a mission with litchi and lost my connection over the harbor. Last thing I saw was what looked like my drone hitting the water... Here's the link to the log:

Phantom Log Viewer - PhantomHelp.com

It looks like it starts going down at 12 min 6.6 seconds. If somebody could take a look and offer some insight as to what happened I would be much obliged

Thanks!

Mike

 

[FantomFlier]

Hi all -

I lost my P3A in the Oakland harbor this morning and I don't know why. I was flying a mission with litchi and lost my connection over the harbor. Last thing I saw was what looked like my drone hitting the water... Here's the link to the log:

Phantom Log Viewer - PhantomHelp.com

It looks like it starts going down at 12 min 6.6 seconds. If somebody could take a look and offer some insight as to what happened I would be much obliged

Thanks!

Mike

The obvious questions :
What was your Litchi setting for "Lost Connection"?
What was the state of the battery?
What was the setting for Battery Low?

 

[folp]

Hi FantomFlier -

"Signal lost behavior for manual flying" is return to home. Battery was fine, 43%. Battery low setting was return to home.

Thanks

Mike



Sent from my iPad using PhantomPilots

 

[PaulSouthport]

Bad news.
In the last few moments it was in rapidly switching between atti and p-gps and sat count dropped.
I can't speculate on the cause - other than possibly significant RF and magnetic interference from the surroundings

 

[Meta4]

I lost my P3A in the Oakland harbor this morning and I don't know why. I was flying a mission with litchi and lost my connection over the harbor. Last thing I saw was what looked like my drone hitting the water...
It looks like it starts going down at 12 min 6.6 seconds. If somebody could take a look and offer some insight as to what happened I would be much obliged

There's not much to go on.
No error messages - (perhaps they might show if you tried Healthydrones?)
Everything looks smooth until 12:05.8 when speed initially slows for a second.
Then altitude starts to drop and speed increases far past normal flight values
Signal was maintained for 5 seconds after the incident and GPS sat numbers drop as the Phantom tumbles and the GPS antenna no longer has a good sky view.
We can eliminate some of the usual suspects but still have to guess what might have been the cause.
Perhaps hitting a bird? Or a catastrophic hardware failure?
It looks like it's down to guesswork on this one.

 

[tevek]

Is it possible that there some major interference ( harbour communication systems?) as you were flying back down along the wharf. For the bulk of the mission, it flew fine until you had started to return on the path past what looks a lot of infrastructure. In the space of a couple of seconds, it looks like the drone was heading for the drink. I guess you didn't manually change over to ATTI as at that distance and height you would be struggling to see and control it, and the number of satellites should have been sufficient to stay in P-GPS mode. It was certainly coming back your way and increasing speed as it headed for the water. I am assuming you were flying in FPV mode as if it were a mission it should have continued despite the loss of communication.

 

[Meta4]

Is it possible that there some major interference ( harbour communication systems?)

It's a major container port and no doubt, there would be various VHF and UHF signals in the air but at worst that would only cause interference that might swamp the signal
It's never going to cause a Phantom to plummet from the sky.

I am assuming you were flying in FPV mode as if it were a mission it should have continued despite the loss of communication.

It had fallen 233 ft in the last 4 seconds of the flight.
When it lost communications, the only place it was going was down and splashdown would have been less than a second after the flight record ends..

 

[tevek]

It's a major container port and no doubt, there would be various VHF and UHF signals in the air but at worst that would only cause interference that might swamp the signal
It's never going to cause a Phantom to plummet from the sky.

It had fallen 233 ft in the last 4 seconds of the flight.
When it lost communications, the only place it was going was down and splashdown would have been less than a second after the flight record ends..

I was trying to think of something other than some internal hardware fault which just so happened to occur on the stretch adjacent to the wharf or he collided with a bird that sent it into a death plunge. Appreciate the comments regarding UHF/VHF and that has largely been done to death here on the forum.

 

[HitFactor]

Perhaps the port has implemented countermeasures for UAS? It's a tricky task to do safely.

 

[Meta4]

Perhaps the port has implemented countermeasures for UAS? It's a tricky task to do safely.

That's extremely unlikely to have been a factor and the flight record gives no reason to think it was.

 

[HitFactor]

Jamming GPS is a method of countermeasure, loss of GPS signal was noted.

 

[Meta4]

Jamming GPS is a method of countermeasure, loss of GPS signal was noted.

No ... the Phantom had full GPS until it started tumbling which reduced the number of sats it could see but it never lost GPS.
And even if somehow GPS was jammed (and you won't find anywhere that is happening for "security"), that just leaves the Phantom drifting slowly as if in atti mode.
It doesn't sent it plunging.

 

[Numone]

I've bought it but, to date, never used it so dumb question - does Litchi record an app video like the GO App? That may help?

 

[Loz]

Could it just have been shot down?


Sent from my iPad using PhantomPilots

 

[Meta4]

Here's about where it went down:

 

[Wessex]

ATTI mode should still maintain height. It relies on the internal barometers to maintain height. Obviously it would drift on any wind. Some one with an air gun taking a pot shot?

The sudden loss of gps lock is a mystery. The top of the drone where the gps receiver is will receive satellite signals no matter what the attitude of the craft.

It does sound like a massive case of electro interference. Another Theory is that the craft flipped and power drove into the drink.

Follow the drone code and don't fly near industrial workings.

Sent from my STV100-4 using PhantomPilots mobile app

 

[Meta4]

ATTI mode should still maintain height. It relies on the internal barometers to maintain height. Obviously it would drift on any wind. Some one with an air gun taking a pot shot?
The sudden loss of gps lock is a mystery. The top of the drone where the gps receiver is will receive satellite signals no matter what the attitude of the craft.
It does sound like a massive case of electro interference. Another Theory is that the craft flipped and power drove into the drink.

No ... I've already explained this.
Atti won't maintain height if it happens when the Phantom is falling due to hardware failure or collision.
The loss of GPS is no mystery at all.
Look at the altitude readings for the period where sat numbers are dropping.
It's clear that the Phantom is falling and tumbling.
When the top of the Phantom is facing up, it has a good view of the sky but when it's down or half way, it's can't see as many sats.
There's no need to make up extremely unlikely scenarios like a massive case of electro interference.

 

[Wessex]

No ... I've already explained this.
Atti won't maintain height if it happens when the Phantom is falling due to hardware failure or collision.
The loss of GPS is no mystery at all.
Look at the altitude readings for the period where sat numbers are dropping.
It's clear that the Phantom is falling and tumbling.
When the top of the Phantom is facing up, it has a good view of the sky but when it's down or half way, it's can't see as many sats.
There's no need to make up extremely unlikely scenarios like a massive case of electro interference.

Seeing as there isn't a definitive answer then are we not allowed to air our thoughts?

The GPS receiver isn't directional. It will receive just as well upside down as well as the correct way up.

@folp trying to throw some possibilities your way. Looks like I haven't a clue what I'm talking about according to some know all.

 

[Meta4]

Seeing as there isn't a definitive answer then are we not allowed to air our thoughts?

You are entitled to your thoughts but if you offer outlandish guesses, expect to be corrected.

The GPS receiver isn't directional. It will receive just as well upside down as well as the correct way up.
@folp trying to throw some possibilities your way.

The GPS antenna is directional.
Go and test for yourself and you'll see that your sat numbers drop by ~50% when you turn the Phantom upside down.
This is what you would see with a tumbling Phantom and it coincides with data showing the Phantom was falling at the time.

Looks like I haven't a clue what I'm talking about according to some know all.

Looks like you were guessing and quite wrong on this.

 

[Wessex]

Lots of replies are guesses. And the antenna is not directional.