Plane Crash Due to Sudden RSSI Critical

[Jim Miller]

Looking for some advice on what happened. Was flying my e-Pike Perfect sailplane like 300' over a treed area when suddenly I got a RSSI critical sensor loss warning back to back and the plane then went down into the trees hard. Still working on getting it down. I have a X18 with G-RX8 receiver and MX back up receiver. As I walked toward where the plane (about 2/3 to plane) I all of a sudden got signal back. Any ideas on the cause, low battery, signal interference, radio or receiver issues? I've lost single on other planes at times but short lived.

 

[HENNY]

Looking for some advice on what happened. Was flying my e-Pike Perfect sailplane like 300' over a treed area when suddenly I got a RSSI critical sensor loss warning back to back and the plane then went down into the trees hard. Still working on getting it down. I have a X18 with G-RX8 receiver and MX back up receiver. As I walked toward where the plane (about 2/3 to plane) I all of a sudden got signal back. Any ideas on the cause, low battery, signal interference, radio or receiver issues? I've lost single on other planes at times but short lived.

How were your antennas located in the model, is your model made from carbon fiber. Did you perform a range check before flying. Were you monitoring RSSI level during your flight. Were you monitoring your battery voltage. Trees can be an issue for 2.4g when flying over or behind trees, especially when the tree leaves are wet. Microwave ovens operate at 2.4g, this is because water readily absorbs the 2.4g energy to heat up the water. If you are flying near or over trees and your receiver antennas are near other objects like batteries, carbon fiber, servos or wiring etc your signal strength can be greatly reduced. A range check would have notified of this. This occurs with all radio types operating on 2.4g. A number of pilots at our field fly when it's raining, this is a risky practice. 900meg is much more tolerant to these type of conditions.

 

[Eric R]

One antenna wire a loose connection or broken wire tip?

 

[Wayne]

Yep - more details would be helpful. I know it is still up in a tree.

Sorry!

You said you have lost signal before with different planes? Yikes! This is a warning sign that something very bad is going on. I have not lost signal while flying since switching to FrSky about 10 years ago. Ok, I flew into the fog once, that ultimately ended up with a lost signal.

Some of our local thermal pilots contend with some localized interference that they have a very hard time flying through. They have learned to avoid the area. I suspect they have a communications beam going through that area.

But radio installation and airframe makeup and component placement can all have a bearing on things. Heck, even the type of ESC can have a major effect on radio performance.

 

[Jim Miller]

Thanks for the above comments. Plane up in the tree still, hoping to resolve that. Regarding antenna placement the tips stick out through the side of a fiberglass pod, both for the main and the satellite receivers. I was thinking maybe the battery got critically low, but wouldn't I have gotten a low RSSI warning before the critical and sensor loss?

 

[Wayne]

Nope, I do think you had a weak RF condition. But do not know why.

Have others had issue in the same area?

 

[HENNY]

Nope, I do think you had a weak RF condition. But do not know why.

Have others had issue in the same area?

Well if the signal state went instantly to critical it probably skipped the low warning.

 

[Jim Miller]

Come to think of it about two months earlier I had a DLG go out of control on me in that same area and I pulled the flaps and it landed hard with little damage at the edge of the woods where my plane is now in the tree. I was more focused at that time about thinking my fail safe wasn't set up right. I don't remember having the RSSI critical warning on that one. I also have had other planes do some wacky things on that field. Could it be my X18 radio? And how would I even tell? I've added satellite receivers in most of my big planes ( like the one in the tree) all based on ASSCT, maybe I should upgrade to Archer?

 

[gnichola]

Just a thought, suppose there is a place where some sort of radio interference is happening. It could affect both the directions of communication and rather than a low/critical signal message, you could be waiting for a telemetry lost message.

 

[Jim Miller]

It's our club field, flown there for years. If there is some sore of interference now on occasion would it help to put a 900 mhz receiver in the bigger sailplanes as a backup and not rely on 2.4 only?

 

[Wayne]

YES -I was going to suggest using Tandem if your gliders have space for the antenna. That way you have 2 different frequencies.

Might be worth a try to take up an old plane you do not care much about and fly it with the telemetry on. Fly around in the areas you have had issues and go back and check your RSSI values in the log.

What we tend to see more and more of is some company has setup some remote equipment and they want to monitor it, so they setup an RF connection that is point to point. They use a very high Db antenna that focuses the energy into a very directional beam. This gives them a reliable connection, but can cause issues for anything that goes through the beam. AT LEAST THIS IS MY THEORY. Could be other things like a localized RF interference.

I fly mostly slope gliders. This means we are often times on the highest ridge or mount around, usually very close to some huge group of antennas that look something like this:

Some radios have a heck of a time working near one of these towers. Normally FrSky gear has little issue with them.

But with more and more radio systems being used by more and more things, we are seeing more and more RF pollution everywhere. This does take a toll on our radios too.

As all of these radio systems age, they tend to get a bit dirtier. Not exactly broadcasting where they should be. With good service, they can be kept in tip top condition, but with bad servicing, well, it becomes about as reliable as a 400,000 mile Buick.

IT IS VERY POSSIBLE THIS IS WHAT YOU ARE DEALING WITH. But you need to do some testing to confirm.