Q. Which of the following statements with regard to Black Boxes used in modern aircrafts is/are correct?
I. They carry a beacon emitting underwater red light pulses to facilitate detection.
II. They record both the cockpit voice and flight data.
III. Their memory units are made using either stainless steel or titanium.
Select the answer using the code given below:
1. (a) 1 only
2. (b) 2 and 3 only
3. (c) 1 and 2 only
4. (d) 1, 2 and 3

Answer : B

Explanation:

Statement 1 is not correct: The Underwater Locator Beacon (ULB) fitted to black boxes emits an ultrasonic pulse at 37.5 kHz i.e. not red light pulses. It is detected by sonar/hydrophone equipment, not by light.
Statement 2 is correct: Flight recorders consist of two functional devices, namely, the Flight Data Recorder (FDR) which records aircraft performance parameters, and the Cockpit Voice Recorder (CVR) which records verbal communication between crew members. Together they capture both voice and flight data.
Statement 3 is correct: Modern FDRs are typically protected from crash damage by a double wrap of strong corrosion-resistant stainless steel, or titanium, on the exterior, with high-temperature insulation inside for protection against fire.

Sources:

https://britannica.com/EBchecked/topic/210220/flight-recorder

https://en.wikipedia.org/wiki/Underwater_locator_beacon

https://patents.justia.com/patent/10054104