Name two types of smoke detection systems used in aircraft.

• A. Light refraction types and ionization types
• B. Ionization types and heat detectors
• C. Light refraction types and infrared types
• D. Optical fiber and thermal expansion types

Answer: (A)

Smoke detection on aircraft relies on two common technologies: optical (light-scatter) detectors and ionization detectors. An optical detector uses a light beam in a chamber and watches for smoke particles that scatter or refract the light into a sensor, triggering an alarm when smoke is present. An ionization detector contains a small radioactive source that creates a continuous ion current between electrodes; when smoke enters the chamber, the current is disrupted and the alarm sounds. These two types cover different fire signatures and together provide reliable early warning in enclosed aircraft spaces. Other detector types like heat sensors or flame-focused infrared detectors do not respond to smoke in the same way, and terms like optical fiber or thermal expansion aren’t standard smoke-detection technologies in aircraft.