What’s “Mountain Waves”?

[Ref AC 00-6B Chapter 17, AC 00-57] Mountain waves are a form of mechanical turbulence which develop above and downwind (Lee side) of mountains ridge. Risk of Mountain waves? Range: This mechanical turbulence may extend 600 miles (1,000 km) or more downwind from the mountain range. Intensity: This mechanical turbulence are classified as severe to […]

What’s Radio Altimeter?

[Ref AVIA4019, ACE The Technical Pilot Interview 146/348] Radio Altimeters (RA) provide an accurate height measurement from 2,500 ft down to 50 ft (AGL – above ground level). Indeed, the function usually are binding with barometric altimeter in most commercial aircraft.   How RA works? The basic principle of the radio altimeter is that a […]

What’s “Primary Systems”

[Ref. Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25B Page 7-1] The primary systems on most GA aircraft include but not limited to: Engine (engine itself + 6 sub-systems) propeller Airframe System electrical system Hydraulic System – e.g landing gear environmental control systems – e.g Oxygen system, Heating System Flight Control System Note : Flight Control system is […]

What’s Volcanic Ash Advisory (VAA) Messages?

[Ref BOM Australia Knowledge Centre, VAA message] Volcanic Ash Advisory (VAA) messages is a kind of SIGMET about volcanic activities. Volcanic Ash Advisory (VAA) messages are issued by 9 Volcanic Ash Advisory Centres (VAACs) over the world. They are located in Darwin (Australia), Anchorage (US), Buenos Aires (Argentina), London (UK), Montreal (Canada) Tokyo (Japan), Toulouse (France), […]

What’s “insolation”?

[Ref ISBN 978-1-61854-262-5] Insulation, “日照” in Chinese, usually refers to the situation that the earth’s surface receives solar radiation. In daytime, peak insolation occurs around 1200LT, but maximum surface air temperature usually occurs during the mid-afternoon; At night, insulation is absent. Therefore, sun’s rays is the major reason causes uneven heating on the earth’s surface. […]

What’s SLG (Semi Levered Gear)?

[Ref Youtube, Boeing] SLG (Semi Levered Gear) is a design that can be found in B777-300ER. A “diagonal” hydraulic strut provides the energy to provide better takeoff performance. The design is used to increase takeoff capability, or provide increased tail clearance for the same weight and thrust as nonequipped airplanes. Below are two photos of triple-bogie. […]