[rottndog]

It is powered by the plane's electrical system, subject to fire, isolate so you have power for other systems.

I understand that...but...how much power dose a transponder use, and how many shorts/fires have been caused by a transponder? If the engines can broadcast their status themselves independent of pilot actions, it can't be that much of a burden for the plane itself to do so.

[rottndog]

dose=does....duh...

[xone]

All it takes fire-wise is one if you've ever had one inflight. I don't remember the requirements, but it was hooked to the main bus. The problem with leaving it on is that everytime it gets interrogated it responds. That would cause a real safety of flight issue. If there was a better way, that didn't cost horrendous amounts of money, it would have been done.

More automation might be the fix for this case, but it will cause more weaknesses that can be exploited. The transponder in this case is a transceiver it has to be controllable. If it couldn't be paused or turned off, anytime you input the code would activate all the codes in between.

[Bobalu]

Because of 911 I’d be astounded if the firmware and or hardware of most of the embedded systems on heavy jets has not been modified to deliver multiple tracking signals when any funny business is detected.

Only a fool would have overlooked doing this. Pilots and maintenance people would not be in the know about this.

Systems that a layman would never suspect are likely rigged to emit rf signals. Given the incredible gain of our satellite based listening gear the rf would only need to be a fraction of a milliwatt.

If I was asked to suggest a warning beacon idea I would place several that would emit rf whenever the plane is at altitude and also has the transponder shut down.