AET Avionics Systems 5 — Questions and Answers
Question 1: What is the significance of ARINC 664 (AFDX) over ARINC 429 in modern avionics?
- AFDX supports bidirectional high-speed Ethernet-based communication versus ARINC 429's unidirectional low-speed links (Correct answer)
- AFDX uses analog signals while ARINC 429 uses digital
- AFDX only works at frequencies above 1 GHz
- AFDX replaces GPS with inertial data
Correct answer: AFDX supports bidirectional high-speed Ethernet-based communication versus ARINC 429's unidirectional low-speed links
ARINC 664 (AFDX) uses switched Ethernet technology enabling bidirectional, high-bandwidth data exchange compared to ARINC 429's slower unidirectional links.
Question 2: A pilot reports the radio altimeter reads zero while airborne over water at 500 feet. The most likely cause is:
- Antenna connector failure or water intrusion in the antenna (Correct answer)
- GPS satellite outage
- Static discharge from precipitation
- ADC barometric sensor blockage
Correct answer: Antenna connector failure or water intrusion in the antenna
Radio altimeter antenna failures or connector corrosion cause false zero or invalid readings because the RF signal path is broken.
Question 3: Which type of display symbology standard governs the presentation of flight data on Primary Flight Displays (PFD) in transport aircraft?
- FAA Advisory Circular AC 25.1302
- SAE AS8034
- ARINC 661 (Correct answer)
- DO-254
Correct answer: ARINC 661
ARINC 661 defines the standard interface and symbology specification for cockpit display systems, including PFD graphics rendering.
Question 4: What does 'BITE' stand for in avionics maintenance contexts?
- Basic Integrated Test Equipment
- Built-In Test Equipment (Correct answer)
- Binary Interface Test Engine
- Bus Isolation and Test Electronics
Correct answer: Built-In Test Equipment
BITE stands for Built-In Test Equipment, onboard self-test circuitry that monitors LRU health and stores fault codes for maintenance retrieval.
Question 5: On a glass cockpit aircraft, what does the magenta triangle on the navigation display (ND) typically represent?
- Airport of departure
- Active waypoint or TO waypoint (Correct answer)
- Traffic alert from TCAS
- Top-of-descent point
Correct answer: Active waypoint or TO waypoint
The magenta triangle on the ND indicates the active TO waypoint that the flight management system is currently navigating toward.
Question 6: What is the primary purpose of the Marker Beacon system in an ILS approach?
- Provide lateral guidance corrections
- Indicate specific distance-to-threshold fix points via audio and visual signals (Correct answer)
- Transmit weather minima to the cockpit
- Control glide slope transmitter power
Correct answer: Indicate specific distance-to-threshold fix points via audio and visual signals
Marker beacons (outer, middle, inner) transmit upward-directed 75 MHz signals that trigger distinct audio tones and cockpit lights at known distance points along the ILS approach path.
Question 7: When troubleshooting an ARINC 429 bus fault, a technician finds all labels on that bus are missing. The most likely cause is:
- Receiver card failure in one LRU
- Transmitter output failure in the source LRU or open wire on the bus pair (Correct answer)
- Incorrect baud rate on a single receiver
- Software version mismatch on one listener
Correct answer: Transmitter output failure in the source LRU or open wire on the bus pair
Since ARINC 429 is unidirectional with one transmitter feeding multiple receivers, a transmitter failure or open bus wire eliminates all labels for every listener on that bus.
AET Avionics Systems 5
What is the significance of ARINC 664 (AFDX) over ARINC 429 in modern avionics?