HF – High Frequency

[Ref AVIA4019, ACE The Technical Pilot Interview 149/348, 150/348] 3-30 MHz (application in aviation from 2 to 22 MHz) uses predictable sky wave propagation paths (i.e refracted off the earth’s ionosphere over great distances) for longer-distance communication but degraded quality and for communications between two specific points only usually for oceanic/desert areas which covers a large […]

Communications, Navigation and Surveillance (CNS)

[Ref AVIA 4019, EUROCONTROL] Communications, navigation and surveillance (CNS) technologies are at the heart of aviation. All of them rely on sufficient frequencies (spectrum) being available. Without CNS and spectrum, air transport could not function.   Communication While air traffic controllers and pilots need to communicate (air-ground) to ensure the safety of flight, there are […]

Aeronautical Information Circular (AIC)

[Ref AVIA4019] Similar to NOTAM but issued by mail Can contain extensive text and/or graphics Usually concerning changes of longer duration or with long lead time A notice containing information that does not qualify for the classification as a NOTAM or AIP, but which relates to flight safety, air navigation, technical, administrative or legislative matters

Aeronautical Information Service (AIS)

[Ref AVIA4019] Objective of Aeronautical Information Service (AIS) The objective of AIS is to ensure the aeronautical information and data flowing orderly in proper format. This information and data are related to safety, regularity and efficiency of international air navigation within entire territory of the State. To achieve the objective, aeronautical information and data are issued primarily […]


[Ref PPL Instruction Kit Vol1 (306) – 9th Edition] In Australia, SARWATCH – a search and rescue ‘watch’ – 3 types: Regular ‘position reports’ (applicable to IFR only); Operations normal’ reports from an aircraft operating on ‘reporting schedules’ (SKEDS); SARTIME – pilot nominating a time for the initiation of SAR action if an arrival report (or […]

Undesired aircraft state

[Ref SKYbrary, Airbus FAST magazine, FAA AC 120-90] What’s an undesired aircraft state? According to FAA doc: Undesired aircraft state – a position, speed, attitude, or configuration of an aircraft that: results from flight crew error, actions, or inaction; and clearly reduces safety margins Undesired aircraft state can be managed effectively, returning the aircraft to safe […]

VFR navigation

[Ref VFRG] If you don’t understand what is VFR? Click here~ During flight pilots must maintain a time reference accurate to within +/- 30 seconds (ref ENR 1.1) The pilot in command (PIC) must navigate the aircraft by visual reference to the ground or water, or by using any of the methods specified in AIP ENR […]


[Ref ACE The Technical Pilot Interview 297/348, SKYbrary] Decision Height (DH) Runway Visual Range (RVR) CAT I DH > 200 ft RVR @ touchdown ≥ 550 m  or Visibility 800 m CAT II 200 ft ≥ DH > 100 ft RVR @ touchdown ≥ 300 m ; RVR @ midpoint ≥ 150 m CAT IIIa 100 ft […]

What’s Transponder? What’s Mode A, Mode C, Mode S?

[Ref. Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25B Page 14-25, SKYbrary] What’s transponder? Transponder is the airborne portion of the secondary surveillance radar (SSR) system. It receives an interrogation signal sending from ground based interrogator, then it send the return signal back to the ground based radarscope.   What’s Mode A, Mode C, Mode S? Mode A equipment transmits […]