Practice Test Geeks(AET) Aircraft Electronics Technician Practice Test
← All AET Flashcard Decks

Data Bus Systems and Protocols Flashcards

6 cards from real AET practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 6 Data Bus Systems and Protocols flashcards as text

  1. What is the primary architectural characteristic of the ARINC 429 data bus used in commercial transport avionics?

    Answer: Unidirectional simplex bus with one transmitter and up to 20 receivers

    ARINC 429 is a simplex (one-way) bus: a single transmitter sends data to up to 20 receivers on the same wire pair. If two-way communication is needed, a second separate ARINC 429 bus must be used in the opposite direction.

  2. What is the maximum data transfer rate of the MIL-STD-1553B data bus commonly used in military aircraft?

    Answer: 1 Mbps

    MIL-STD-1553B operates at a fixed 1 Megabit per second (1 Mbps). It uses a time-division multiplexing scheme and a command/response protocol managed by the Bus Controller.

  3. In a MIL-STD-1553B network, which device is responsible for managing and initiating all data transfers on the bus?

    Answer: Bus Controller (BC)

    The Bus Controller (BC) initiates all transactions on a MIL-STD-1553B bus. Remote Terminals (RTs) respond only when commanded by the BC. The Bus Monitor (BM) passively records traffic without participating in transfers.

  4. How many bits are contained in each ARINC 429 data word?

    Answer: 32 bits

    Each ARINC 429 transmission consists of a 32-bit word, divided into a label field (bits 1–8), a source/destination identifier (bits 9–10), data field (bits 11–28), sign/status matrix (bits 29–30), and a parity bit (bit 32).

  5. What is the primary advantage of ARINC 664 (AFDX — Avionics Full-Duplex Switched Ethernet) over ARINC 429 in modern aircraft?

    Answer: Vastly higher bandwidth and bidirectional data flow on a single connection

    ARINC 664/AFDX provides 10/100 Mbps full-duplex bandwidth, supporting bidirectional communication over a single connection — a dramatic improvement over ARINC 429's 12.5 kbps or 100 kbps unidirectional bus. It is used in aircraft such as the Airbus A380 and Boeing 787.

  6. Why is fiber optic cable preferred over copper wiring for certain aircraft data bus applications?

    Answer: Fiber optic provides immunity to electromagnetic interference and is unaffected by lightning-induced transients

    Optical fiber transmits data as light pulses and has no metallic conductors, making it completely immune to EMI, RFI, and lightning-induced voltage transients — a significant advantage in the electromagnetically demanding environment of an aircraft.