why the spark ignition system in aircraft is the most used

As far as we know, my captain fiance and I, there is no other ignition source.

reciprocating aircraft engines that burn gasoline use a dual magneto type of ignition system. (it is basically a pair of electric generators that produce more electricity the more rpm is u turn them.) aircraft diesel engines run on the same principle as any diesel.under high compression, temperature is increased thereby igniting the diesel fuel. in jet engines they use ignitor plugs or spark shower plugs. (ignitor plugs r basically glow plugs, they have an electric coil on the tip which glows red hot igniting the fuel. it glows continuously to ensure constant burn & prevent flame out.) spark shower plugs create a continous shower of sparks to ignite the jet fuel. (jet fuel is basically kerosene that has additional additives & is cleaner than regular kerosene.

In principle you could build a diesel powered aircraft, but a diesel engine is too heavy relative to its power output to be an efficient power unit for flying.

As for piston engines in aircraft they use spark plugs powered by magnetos. There r 2 magnetos..each one can spark all cylinders if one fails. Having 2 magnetos & 2 spark plugs also aids in even fuel burn in cylinder & safety/redundancy.

I belive the few aviation diesels dont need spark plugs.

As for Turbine engines..Turboprops & Jets. They use spark ignition for start, restart, & for certain atmopheric conditions & flight modes such as takeoff & landing.
A turbine engine only needs ingition to start since they r self igniting once started. If one fails (flameout) in flight the igniters (on some) will automatically come on to attemp a relight. We also turn then ON (continuous ignition) for flying in iciing condtions & for takeoff & landing. (Procedure in a Beechjet 400)

With the exception of diesels, all piston-type engines, in cars, truck, boats, airplanes, construction machines, or any other vehicle, use a ''spark ignition system.'' You need to do an internet search on ''piston engine cycles'' to find out how these systems work.

Older ignition systems used a mechanical firing device with electrical contacts and condenser. More modern systems tend to be all-electronic, without contacts to wear out.