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Aircraft systems and instrumentsQuestion 578 of 934

How does a spark ignition engine ignite the fuel-air mixture?

  1. With a spark plug
  2. By compressing the air until it is very hot
  3. By heat from the exhaust valve
  4. By a glow plug in the induction system
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Correct answer: With a spark plug

Spark ignition engines use a spark plug to ignite a pre-mixed fuel-air mixture. A compression ignition engine uses hot compressed air.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 7: Aircraft Systems — Reciprocating Engines, page 162

Practice aircraft systems and instruments

Questions last reviewed: 18 October 2026