Under what circumstances is a kill switch used?
How is it activated? By radio or manually?
Where located and in what circuit?
Laurence

I am assuming by kill switch you mean on the throttle..as I can't think of any other time you'd want to shut down your aircraft while operating..
On a glow engine throttle cut is a function of trim..you program a computer radio so that when you a throw a switch to run, you have cracked the carb open to idle....on shut down you when you throw the switch you close the carb completly...the engine shuts down..you do the same thing on a non computer radio with throtle trim manually..
On a gas engine there is also a switch to kill ignition..
Hope I understood your question correctly

Kill switchs are normally used when a plane has a gasoline engine in it. The kill switch is actually a switch that will disrupt the ignition system of the engine so that it will not run. Some people will put this kill switch on a plane controlled by a servo so that they can kill the plane with the radio, while others put them on the plane as a seperate switch that is manually activated. These can be very important on gas engines for safety so that the engine can't accidentally start running if it's turned over.

Ken

Gentlemen,
I was not specific enough with my question. I should have asked it relative to a gas engine. You have seen through that; my question has been answered.
Thank you.
Laurence

i dont know for sure but i thought this was popular with helicopter radios too

Most Gas engines use both a mechaical kill with access outside the fuse.
and a radio operated killswitch, Wiring of the switches depends on the
type of engine, electronic igntions you can just kill the power to the
ignition box, Magneto engines you can add a ground to the coil.

Like Ken said it is a definite safety issue, All fuel powered planes should have some
way to shut the engine from the transmitter.

Smart-Fly makes a very popular kill switch.

It's actually "popular" with any model with ANY kind of motor or engine whether it be electric, nitro, gas or turbine. Exact "best" reasons vary. You need to be able to stop the prop or rotor from the TX for safety reasons.