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Question 1. In an aircraft DC circuit, if the voltage is 28 V and the resistance is 7 Ω, what is the current? A) 2 A B) 4 A C) 7 A D) 14 A Answer: B Explanation: Using Ohm’s Law (I = V/R), I = 28 V / 7 Ω = 4 A. Question 2. A 5 Ω resistor and a 10 Ω resistor are connected in series across a 30 V supply. What is the voltage drop across the 10 Ω resistor? A) 10 V B) 15 V C) 20 V D) 30 V Answer: C Explanation: Total resistance = 15 Ω, total current = 30 V/15 Ω = 2 A. Voltage across 10 Ω = I × R = 2 A × 10 Ω = 20 V. Question 3. In a parallel circuit of two resistors, 12 Ω and 6 Ω, connected to a 24 V source, what is the total current drawn from the source? A) 1 A B) 2 A C) 3 A D) 4 A Answer: D Explanation: Conductance of 12 Ω = 1/12, of 6 Ω = 1/6. Total conductance = 1/12 + 1/6 = 1/4 S, so total resistance = 4 Ω. I = V/R = 24 V/4 Ω = 6 A. Wait calculation error: Actually total resistance for parallel: 1/R_total = 1/12 + 1/ = 0.0833 + 0.1667 = 0.25 → R_total = 4 Ω. Current = 24 V/4 Ω = 6 A. None of the options. Adjust answer: Option D (4 A) is closest but incorrect. Let's correct options. Replace with correct options. Corrected Question 3. In a parallel circuit of two resistors, 12 Ω and 6 Ω, connected to a 24 V source, what is the total current drawn from the source? A) 2 A B) 3 A C) 4 A D) 6 A Answer: D Explanation: Parallel resistance = 4 Ω, so I = 24 V/4 Ω = 6 A.
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Question 4. The reactance of a 0.1 H inductor at 400 Hz is closest to: A) 25 Ω B) 40 Ω C) 63 Ω D) 80 Ω Answer: C Explanation: XL = 2πfL = 2π × 400 × 0.1 ≈ 251 Ω? Wait compute: 2π × 400 = 2513, times 0.1 = 251 Ω. That's not in options. Let's adjust numbers. Use 0.025 H at 400 Hz: XL = 2π × 400 × 0.025 ≈ 62.8 Ω ≈ 63 Ω. Corrected Question 4. The reactance of a 0.025 H inductor at 400 Hz is closest to: A) 25 Ω B) 40 Ω C) 63 Ω D) 80 Ω Answer: C Explanation: XL = 2πfL = 2π × 400 × 0.025 ≈ 62.8 Ω ≈ 63 Ω. Question 5. A capacitor of 10 μF is subjected to a 60 Hz AC source. What is its capacitive reactance (Xc)? A) 0.27 Ω B) 2.65 Ω C) 26.5 Ω D) 265 Ω Answer: C Explanation: Xc = 1/(2πfC) = 1/(2π × 60 × 10 × 10⁻⁶) ≈ 265 Ω? Compute: 2π × 60 = 376.99, ×10 μF (10e-6) = 0.00377, 1/0.00377 ≈ 265 Ω. So answer D. Let's correct options. Corrected Question 5. A capacitor of 10 μF is subjected to a 60 Hz AC source. What is its capacitive reactance (Xc)? A) 2.65 Ω B) 26.5 Ω C) 265 Ω D) 2 650 Ω Answer: C Explanation: Xc = 1/(2πfC) ≈ 1/(2π × 60 × 10 × 10⁻⁶) ≈ 265 Ω.
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Question 10. In a MOSFET, the gate draws essentially no current because the input is: A) Resistive B) Capacitive C) Inductive D) Reactive Answer: B Explanation: The MOSFET gate is insulated by an oxide layer, presenting a high-impedance (capacitive) input, so virtually no DC current flows. Question 11. An operational amplifier configured as a non-inverting amplifier has a gain of 5. Which resistor ratio provides this gain? A) Rf = 4 kΩ, Rin = 1 kΩ B) Rf = 1 kΩ, Rin = 4 kΩ C) Rf = 5 kΩ, Rin = 0 kΩ D) Rf = 0 kΩ, Rin = 5 kΩ Answer: A Explanation: Gain = 1 + (Rf/Rin). To get 5, Rf/Rin = 4, so Rf = 4 kΩ and Rin = 1 kΩ. Question 12. Convert the binary number 110101₂ to decimal. A) 45 B) 53 C) 61 D) 69 Answer: B Explanation: 1·2⁵ + 1·2⁴ + 0·2³ + 1·2² + 0·2¹ + 1·2⁰ = 32 + 16 + 0 + 4 + 0 + 1 = 53. Question 13. The BCD representation of decimal 9 is: A) 1001 B) 0110 C) 1010 D) 1100 Answer: A Explanation: In BCD, each decimal digit is encoded as its 4-bit binary equivalent; 9 = 1001 ₂.
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Question 14. Which Boolean expression represents the output of a NAND gate with inputs A and B? A) A · B B) ¬(A · B) C) A + B D) ¬A · ¬B Answer: B Explanation: NAND output is the negation of the AND operation: Y = ¬(A·B). Question 15. Simplify the Boolean expression: A·B + A·¬B. A) A B) B C) ¬A D) 0 Answer: A Explanation: Using the distributive law, A·(B + ¬B) = A·1 = A. Question 16. A microprocessor has a 16-bit address bus and a 8-bit data bus. What is the maximum addressable memory size? A) 8 KB B) 16 KB C) 64 KB D) 256 KB Answer: C Explanation: 2¹⁶ = 65,536 bytes ≈ 64 KB. Question 17. In ARINC 429, the label field occupies which bits? A) 1- 8 B) 9- 16 C) 17- 24 D) 25- 32 Answer: A Explanation: The first 8 bits of an ARINC 429 word are the label, transmitted MSB first. Question 18. Which ARINC 429 transmission mode provides the highest data rate? A) Low-speed (12.5 kbps) B) High-speed (100 kbps) C) Medium-speed (25 kbps) D) Variable-speed (up to 1 Mbps)
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Answer: A Explanation: VSWR = 1:1 means no reflected power; the transmission line is perfectly matched to the load. Question 23. HF skywave propagation relies primarily on reflection from which ionospheric layer during daytime? A) D-layer B) E-layer C) F1-layer D) F2-layer Answer: D Explanation: The F2-layer, present both day and night, provides the highest critical frequency for long-range HF propagation. Question 24. A satellite communication system uses an Inmarsat L-band antenna. Which frequency range does the L-band cover? A) 1- 2 GHz B) 2- 4 GHz C) 4- 8 GHz D) 8- 12 GHz Answer: A Explanation: Inmarsat L-band operates roughly between 1.5 GHz and 1.6 GHz. Question 25. In a cockpit voice recorder (CVR), the primary storage medium is: A) Magnetic tape B) Solid-state memory C) Optical disc D) Floppy disk Answer: B Explanation: Modern CVRs use solid-state memory for durability and resistance to impact. Question 26. The VOR provides azimuth information by comparing which two signals? A) AM and FM B) Reference and Variable C) Left and Right circular polarization D) GPS and LORAN
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Answer: B Explanation: VOR transmits a reference (omnidirectional) signal and a rotating variable signal; the phase difference gives bearing. Question 27. In an ILS localizer, the carrier frequency is: A) 108.00-112.00 MHz B) 108.10-111.95 MHz C) 108.10-111.95 MHz for localizer only D) 108.10-111.95 MHz for glideslope only Answer: C Explanation: ILS localizer uses 108.10 MHz to 111.95 MHz; the glideslope occupies 329.15-335.00 MHz. Question 28. The DME calculates slant-range distance using: A) Time-of-flight of a single pulse B) Phase difference between two continuous waves C) Time difference between transmitted interrogation and received reply D) GPS triangulation Answer: C Explanation: DME measures the round-trip time of interrogation and reply pulses; distance = (Δt × c)/2. Question 29. GPS trilateration requires a minimum of how many satellites to provide a three-dimensional position fix? A) 2 B) 3 C) 4 D) 5 Answer: C Explanation: Four satellites are needed to solve for latitude, longitude, altitude, and clock bias. Question 30. WAAS improves GPS accuracy primarily by:
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Question 34. X-band weather radar operates at approximately: A) 1 GHz B) 3 GHz C) 9 GHz D) 35 GHz Answer: C Explanation: X-band weather radar uses frequencies around 9 GHz, providing high resolution but higher attenuation in heavy rain. Question 35. A pitot-static system provides which three primary flight parameters? A) Heading, altitude, air temperature B) Airspeed, altitude, vertical speed C) Fuel flow, engine RPM, oil pressure D) GPS position, wind speed, true airspeed Answer: B Explanation: Pitot-static instruments derive indicated airspeed, altimeter (pressure altitude), and vertical speed indicator readings. Question 36. RVSM certification requires which of the following altitude-keeping capabilities? A) ±500 ft accuracy between FL290-FL410 B) ± 100 ft accuracy at all altitudes C) ± 1 000 ft accuracy below FL180 D) No specific requirement Answer: A Explanation: RVSM (Reduced Vertical Separation Minimum) mandates altitude measurement accuracy of ±500 ft for aircraft operating between flight levels 290 and 410. Question 37. Gyroscopic precession causes a force in which direction relative to the applied torque? A) Same direction B) Opposite direction C) 90° ahead of torque D) 90° behind torque
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Answer: D Explanation: Precession results in a reaction force 90° behind the direction of the applied torque. Question 38. An AHRS typically combines data from which sensors? A) Pitot tube and static port B) Accelerometers, gyroscopes, and magnetometers C) GPS and VOR D) Radar altimeter only Answer: B Explanation: AHRS fuses inertial measurement unit (accelerometers, gyros) and magnetometer data to compute attitude and heading. Question 39. In an autopilot servo actuator, the feedback loop commonly uses which type of sensor? A) Thermocouple B) LVDT (Linear Variable Differential Transformer) C) Photodiode D) Hall-effect current sensor Answer: B Explanation: LVDTs provide precise position feedback for hydraulic or electric servo actuators in autopilot systems. Question 40. LNAV in an FMS provides guidance based on: A) GPS waypoints only B) VOR radials C) Flight plan geometry (waypoints) D) Air Traffic Control vectors Answer: C Explanation: LNAV (Lateral Navigation) follows the sequence of waypoints defined in the flight plan, regardless of navigation source. Question 41. Which wire type is commonly used for high-temperature aircraft applications? A) Tefzel B) Kapton C) PVC D) Nylon-braided
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A) Measure voltage levels B) Detect open or short faults in a cable by observing reflected waveforms C) Generate high-frequency signals D) Calibrate altimeters Answer: B Explanation: TDR sends a fast pulse down a cable and analyzes reflections to locate impedance discontinuities. Question 46. According to FAA Part 91.413, transponder altitude encoding must be checked at what interval? A) Every 24 months B) Every 12 months C) Every 6 months D) Every 30 days Answer: B Explanation: The transponder’s altitude encoding must be tested and calibrated at least annually. Question 47. FAA Form 337 is required for: A) Routine oil changes B) Minor line-replaceable unit (LRU) swaps C) Major repairs and alterations D) Pilot logbook entries Answer: C Explanation: Form 337 documents major repairs or alterations to an aircraft’s structure or systems. Question 48. In a binary counter, the next state after 0111₂ is: A) 1000₂ B) 0100₂ C) 0010₂ D) 1110₂ Answer: A Explanation: Adding 1 to 0111₂ yields 1000₂ (binary overflow to the next bit). Question 49. Which logic gate produces a high output only when an odd number of inputs are high?
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A) AND B) OR C) XOR D) NAND
Answer: C Explanation: XOR (exclusive-OR) outputs true when the number of true inputs is odd. Question 50. The parity bit in ARINC 429 is used to: A) Indicate message priority B) Detect single-bit errors C) Provide time-stamp D) Identify the source aircraft Answer: B Explanation: The parity bit (odd parity) allows the receiver to detect if a single bit has been corrupted during transmission. Question 51. A 4-to-16 line decoder with enable input receives a binary code 1010₂. Which output line is active? A) Y10 B) Y5 C) Y8 D) Y Answer: A Explanation: Binary 1010₂ equals decimal 10; the decoder activates output line Y10 when enabled. Question 52. In a dual-redundant MIL-STD-1553 bus, the word format includes a 3-bit sync, 16-bit data, and a 1-bit parity. How many bits are transmitted per word? A) 20 B) 24 C) 30 D) 32 Answer: D Explanation: Word = 3 (sync) + 16 (data) + 1 (parity) + 8 (command/status) = 28? Wait typical MIL-STD-1553 word is 20 bits (3 sync + 16 data + 1 parity). The correct answer is 20 bits. Adjust options.
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Question 56. A GPS L1 signal carrier frequency is: A) 1.57542 GHz B) 1.2276 GHz C) 2.2 GHz D) 5 GHz Answer: A Explanation: The civilian GPS L1 carrier is 1.57542 GHz. Question 57. The squitter in ADS-B is transmitted on which frequency? A) 1090 MHz B) 978 MHz C) 121.5 MHz D) 122.8 MHz Answer: A Explanation: ADS-B Out uses 1090 MHz ES-AS (Extended Squitter) for broadcast. Question 58. In TCAS, if two aircraft receive opposite RAs (one climb, one descend), what is the likely cause? A) Sensor malfunction B) Incorrect altitude encoding C) Lack of Mode S data exchange D) Aircraft are on non-cooperative frequencies Answer: B Explanation: Opposite RAs usually indicate an altitude reporting error (e.g., transponder altitude mismatch). Question 59. The “tilt” function on weather radar is used to: A) Change the frequency B) Adjust the antenna elevation angle to avoid ground clutter C) Increase transmitted power D) Switch between X-band and C-band Answer: B Explanation: Tilting the radar antenna changes its elevation angle, helping to eliminate ground returns and focus on weather cells.
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Question 60. The static pressure port for the altimeter is typically located on: A) The nose of the aircraft B) The wing leading edge C) The vertical stabilizer D) The pressure-sensitive side of the fuselage Answer: D Explanation: The static port is placed on the side of the fuselage where airflow is relatively undisturbed, providing accurate pressure for altitude measurement. Question 61. A gyroscope that maintains its spin axis in space due to rigidity in space is called a: A) Mechanical gyro B) Ring laser gyro C) Fiber-optic gyro D) All of the above Answer: D Explanation: All listed gyroscopes rely on rigidity in space to provide a stable reference. Question 62. In an AHRS, drift errors are primarily corrected by: A) GPS updates B) Magnetometer data C) Barometric altitude D) Pitot-static inputs Answer: B Explanation: Magnetometers provide heading reference that helps correct yaw drift in inertial sensors. Question 63. A servo actuator in an autopilot uses hydraulic fluid. The primary advantage of hydraulic actuation over electric is: A) Lower weight B) Faster response time C) Higher force density D) No maintenance required Answer: C
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Answer: C Explanation: The continuity beep sounds when the resistance between probes is below a set threshold, indicating a short or good connection. Question 68. The standard frequency for a VHF navigation beacon (VOR) is: A) 108 MHz B) 115 MHz C) 117.95 MHz D) 118 MHz to 136.975 MHz Answer: D Explanation: VOR stations transmit within the aviation VHF band 108 - 136 MHz, with specific allocations for each station. Question 69. In a digital system, “debouncing” is required for: A) High-frequency oscillators B) Mechanical switches to eliminate false transitions C) Power supplies D) Antenna tuning circuits Answer: B Explanation: Mechanical contacts may bounce, causing multiple rapid transitions; debouncing filters these spurious signals. Question 70. The term “BITE” in avionics testing stands for: A) Built-In Test Equipment B) Binary Interface Transfer Engine C) Basic Integrated Timing Emulator D) Battery Isolation Test Equipment Answer: A Explanation: BITE (Built-In Test Equipment) provides onboard diagnostic capability for avionics units. Question 71. The primary purpose of a ground-plane in a printed circuit board (PCB) used in avionics is to: A) Provide mechanical strength B) Reduce electromagnetic interference and provide a return path C) Increase thermal resistance D) Act as a fuse
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Answer: B Explanation: Ground planes create a low-impedance return path and help shield and reduce EMI. Question 72. A 12 V aircraft battery is measured to have an open-circuit voltage of 12.6 V. This indicates: A) Fully discharged B) Normal charge level C) Over-charged D) Faulty battery Answer: B Explanation: A healthy 12 V lead-acid battery typically reads 12.5-12.7 V when at rest, indicating proper charge. Question 73. In an ARINC 664 Ethernet network, which protocol ensures deterministic data delivery? A) TCP B) UDP C) AFDX Virtual Link scheduling D) FTP Answer: C Explanation: AFDX uses virtual link scheduling with BAG to guarantee deterministic bandwidth and delivery. Question 74. The main advantage of using fiber-optic cables in modern avionics data buses is: A) Lower cost B) Immunity to electromagnetic interference C) Higher voltage handling D) Easier splicing Answer: B Explanation: Fiber optics are immune to EMI, making them ideal for high-speed data transmission in the noisy aircraft environment. Question 75. A 4-pole, double-throw (DPDT) switch can be used to:
