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

The correct answer is Option B (2 and 3 only).

Statement 1 is incorrect: Aircraft black boxes do not use red light pulses for underwater detection, as visible light rapidly attenuates and cannot travel far in deep ocean environments. Instead, they are equipped with an Underwater Locator Beacon (ULB) that emits ultrasonic acoustic pulses (pings), typically at a frequency of 37.5 kHz. Sound travels highly effectively underwater, allowing search teams using towed hydrophones to detect the acoustic beacon from kilometers away.

Statement 2 is correct: The term "black box" colloquially refers to two critical recording devices mandated by aviation authorities like the International Civil Aviation Organization (ICAO) and the Federal Aviation Administration (FAA). These are the Cockpit Voice Recorder (CVR), which records radio transmissions and ambient cockpit sounds, and the Flight Data Recorder (FDR), which logs hundreds of technical parameters such as altitude, airspeed, and flight control inputs.

Statement 3 is correct: To protect the digital data during severe accidents, the internal solid-state memory boards are housed in a Crash-Survivable Memory Unit (CSMU). Following stringent EUROCAE ED-112 crash standards, the CSMU's outer armor is cast from heavy-duty stainless steel or titanium. This robust casing allows the unit to survive massive impact forces (up to 3,400 Gs), crushing deep-sea hydrostatic pressure, and extreme thermal fires exceeding 1,100 °C.

Key Takeaway: Despite the name, modern black boxes are painted bright "international orange" for visibility. They contain both the CVR (Voice) and FDR (Data), are shielded by highly durable titanium or stainless steel, and rely on ultrasonic sound (not light) for underwater location.