Definition
An ignition system in which each cylinder of a piston aircraft engine is fired by two independent spark plugs, each driven by a separate magneto. Both magnetos operate simultaneously during normal flight, providing redundancy and improved combustion.
Plain English
Each cylinder has two spark plugs powered by two separate ignition sources, so the engine keeps running even if one ignition source fails.
Context Anchor
Encountered during the before-takeoff engine check, when the pilot checks each ignition side separately before departing.
Derivation
Dual comes from Latin dualis, meaning 'two.' Ignition comes from Latin ignire, 'to set on fire.' Together: two independent systems for setting the fuel-air mixture on fire inside each cylinder.
Why Pilots Care
Gives immediate backup if one magneto or set of plugs fails and produces more complete combustion for better power and cooling.
Intuition Check
Dual ignition does not mean the airplane has two engines. It means one engine has two separate spark systems for each cylinder.
Example Sentence 1
During the run-up, the pilot confirmed dual ignition was working correctly by checking each magneto in turn and observing only a small rpm drop on each.
Example Sentence 2
After landing the pilot noted that one magneto had been rough, so maintenance checked both sides of the dual ignition before the next flight.