Q1: When should a pilot make use of blind transmissions? ^t90q1

Correct: D)

Explanation: A blind transmission is used when the pilot cannot receive responses (e.g., due to a faulty receiver) but has reason to believe the ground station can still hear the transmissions, allowing ATC to track the aircraft's position and intentions. Option A describes a broadcast, not a blind transmission. Option B is not a recognised scenario for blind transmissions. Option C describes a situation requiring two-way communication or an urgency declaration, not a blind transmission.

Q2: What is the standard abbreviation for the term "abeam"? ^t90q2

Correct: C)

Explanation: ABM is the ICAO-standard abbreviation for "abeam," meaning a position at a right angle to the aircraft's track — directly to the side. This abbreviation appears in flight plans, ATC communications, and aeronautical charts. Options A, B, and D are not recognised ICAO abbreviations for this term.

Q3: What abbreviation represents "visual flight rules"? ^t90q3

Correct: B)

Explanation: VFR stands for Visual Flight Rules, the regulatory framework under which pilots navigate by visual reference to the ground and other aircraft. Option A (VMC) stands for Visual Meteorological Conditions, which describes the weather requirements for VFR flight — related but distinct. Options C and D are not standard aviation abbreviations.

Q4: What is the ICAO abbreviation for "obstacle"? ^t90q4

Correct: C)

Explanation: OBST is the ICAO-standard abbreviation for obstacle, used in NOTAMs, aeronautical charts, and ATC communications. Option A (OBS) can mean "observe" or "observation" in ICAO documentation but does not denote obstacle. Options B and D are not recognised ICAO abbreviations.

Q5: What does the abbreviation "FIS" represent? ^t90q5

Correct: D)

Explanation: FIS stands for Flight Information Service — a service providing pilots with information useful for the safe and efficient conduct of flights, including weather updates, NOTAMs, and traffic advisories. Options A and C contain "flashing," which has no relevance to this aviation service. Option B incorrectly uses "system" instead of "service."

Q6: What does the abbreviation "FIR" represent? ^t90q6

Correct: C)

Explanation: A Flight Information Region (FIR) is a defined volume of airspace within which flight information service and alerting service are provided under ICAO standards. Each country or group of countries has one or more FIRs covering all airspace vertically and horizontally. Options A, B, and D are fabricated terms with no aviation meaning.

Q7: What does the abbreviation "H24" indicate? ^t90q7

Correct: D)

Explanation: H24 indicates continuous 24-hour service — the facility is staffed and operational at all times. This designation appears in AIP entries and NOTAMs for facilities like major ATC centres. Option A describes HN (night hours). Option B describes HJ (daylight hours). Option C describes HX (no specific hours).

Q8: What does the abbreviation "HX" indicate? ^t90q8

Correct: B)

Explanation: HX means the facility operates at no specific or predetermined hours and may be available on request or intermittently. Pilots must check NOTAMs or contact the facility to verify availability. Option A describes HN (sunset to sunrise). Option C describes H24 (continuous). Option D describes HJ (sunrise to sunset).

Q9: To which value must the altimeter be set so that it reads zero on the ground? ^t90q9

Correct: C)

Explanation: QFE is the atmospheric pressure at aerodrome elevation. When set on the altimeter subscale, the instrument reads zero on the ground at that aerodrome, displaying height above field during the circuit. Option A (QNH) gives altitude above mean sea level. Option B (QNE) refers to the standard pressure setting of 1013.25 hPa. Option D (QTE) is a true bearing from a station, not an altimeter setting.

Q10: What altitude does the altimeter display when set to a given QNH value? ^t90q10

Correct: D)

Explanation: QNH is the altimeter setting that, when dialled in, causes the altimeter to indicate altitude above mean sea level (AMSL), which is the standard reference for navigation and airspace limits below the transition altitude. Option A is not a standard altimetry reference. Option B describes QFE behaviour. Option C describes QNE (standard pressure) behaviour.

Q11: What altitude does the altimeter display when set to a given QFE value? ^t90q11

Correct: C)

Explanation: With QFE set, the altimeter reads height above the reference aerodrome — the difference between actual pressure altitude and the aerodrome pressure level, showing zero on the ground and direct height above field in the circuit. Option A is not a standard reference. Option B describes QNH behaviour. Option D describes QNE behaviour.

Q12: What is the proper term for a message used in air traffic control? ^t90q12

Correct: D)

Explanation: ATC messages — including clearances, instructions, position reports, and traffic information — are classified as flight safety messages, the third-highest priority after distress and urgency in the ICAO message hierarchy. Option A (regularity messages) concern the operation and maintenance of facilities. Option B (direction-finding messages) relate to radio navigation assistance. Option C (meteorological messages) pertain to weather information.

Q13: How are distress messages defined? ^t90q13

Correct: B)

Explanation: A distress message (MAYDAY) is transmitted when an aircraft and its occupants face a grave and imminent danger requiring immediate assistance — the highest priority category in aeronautical communications, signalled by transponder code 7700. Option A is too vague and could apply to several message types. Option C describes urgency messages (PAN PAN). Option D describes regularity messages.

Q14: How are urgency messages defined? ^t90q14

Correct: A)

Explanation: Urgency messages (PAN PAN) concern a condition that is serious and affects the safety of the aircraft or persons but does not yet constitute a grave and imminent danger requiring immediate assistance — examples include controllable engine problems or medical situations on board. Option B defines distress messages (MAYDAY). Option C is a general description that could fit multiple message types. Option D duplicates option A.

Q15: How are regularity messages defined? ^t90q15

Correct: C)

Explanation: Regularity messages relate to the operation and maintenance of facilities necessary for flight operations — essentially administrative and logistical communications with the lowest priority in the ICAO hierarchy. Option A describes urgency-related messages. Option B defines distress messages. Option D describes flight safety messages.

Q16: Among the following messages, which one has the highest priority? ^t90q16

Correct: D)

Explanation: A request for QDM (magnetic heading to steer toward a station) implies the pilot may be lost or unable to navigate independently, making it a potential urgency or flight safety matter with higher priority than routine operational messages. Options A (QNH) and B (wind) are routine advisory information. Option C (turn left) is a standard ATC instruction but carries lower priority than a navigation assistance request.

Q17: How should the call sign HB-YKM be correctly transmitted? ^t90q17

Correct: C)

Explanation: Using the ICAO phonetic alphabet: H = Hotel, B = Bravo, Y = Yankee, K = Kilo, M = Mike. Option A uses "Home" instead of "Hotel" and "Mikro" instead of "Mike." Option B uses "Yuliett" (which is J = Juliett, not Y) and "Mikro." Option D uses "Home" and "Yuliett." Only option C uses all correct ICAO phonetic words.

Q18: How should the call sign OE-JVK be correctly transmitted? ^t90q18

Correct: A)

Explanation: Using the ICAO phonetic alphabet: O = Oscar, E = Echo, J = Juliett, V = Victor, K = Kilo. Option B uses "Omega" (not ICAO) and "Kilogramm." Option C uses "Omega" and "Jankee" (neither is ICAO standard). Option D uses "Jankee" and "Kilogramm." Only option A uses all correct ICAO phonetic words.

Q19: How is an altitude of 4500 ft correctly transmitted? ^t90q19

Correct: C)

Explanation: ICAO phraseology for altitudes uses "thousand" and "hundred" where appropriate: 4500 ft is spoken as "four thousand five hundred." Option A adds unnecessary zeros after "five." Option B reverses the structure nonsensically. Option D uses digit-by-digit recitation, which is reserved for transponder codes and QNH values, not altitudes.

Q20: How is a heading of 285 degrees correctly transmitted? ^t90q20

Correct: A)

Explanation: Headings and bearings are always transmitted as three individual digits spoken separately: "two eight five." The words "hundred" are never used for headings because digit-by-digit transmission eliminates ambiguity. Options B and C use "hundred" or natural number forms, which are not correct for heading transmissions. Option D adds "hundred" after the digits, which is meaningless.

Q21: How is a frequency of 119.500 MHz correctly transmitted? ^t90q21

Correct: C)

Explanation: Frequencies are transmitted digit by digit with "decimal" for the decimal point, and trailing zeros after significant digits are dropped. 119.500 MHz becomes "one one niner decimal five." Note "niner" is used for 9 to prevent confusion with "nein" (no). Option A retains unnecessary trailing zeros. Option B inserts "tousand" which is not used for frequencies. Option D keeps one trailing zero unnecessarily.

Q22: How is the directional information "12 o'clock" correctly transmitted? ^t90q22

Correct: C)

Explanation: Clock positions for traffic advisories are spoken as the full number followed by "o'clock": "twelve o'clock" means directly ahead. Option A splits "twelve" into digits, which could be confused with other numerical data. Option B omits "o'clock," making the reference ambiguous. Option D adds "hundred," which has no meaning in clock position references.

Q23: In what time format are times transmitted in aviation? ^t90q23

Correct: C)

Explanation: All aeronautical communications use Coordinated Universal Time (UTC), formerly known as GMT or Zulu time, ensuring consistency across time zones worldwide. Pilots must convert local time to UTC for all flight plans, ATC communications, and weather reports. Options A, B, and D all reference local or regional time systems that would cause confusion in international operations.

Q24: When there is doubt about ambiguity, how should a time of 1620 be transmitted? ^t90q24

Correct: D)

Explanation: When there is any risk of ambiguity, ICAO requires the full four-digit UTC time spoken as individual digits: "one six two zero." This eliminates confusion about whether minutes alone or the complete time is being given. Option A gives only the minutes, which could be ambiguous. Option B uses natural number grouping, which is non-standard. Option C uses "tousand" and "hundred," which are not used for time transmission.

Q25: What does the phrase "Roger" mean? ^t90q25

Correct: B)

Explanation: "Roger" is an acknowledgement of receipt only — it means "I have received all of your last transmission" and nothing more. It does not imply agreement, compliance, or permission. Option A defines "Approved." Option C defines "Correction." Option D defines "Wilco" (will comply). Pilots must use the correct phrase to avoid dangerous misunderstandings.