What’s the difference between flying over land and over water at daytime? (Convective currents)

[Ref Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25B Page 12-7] Q: What’s the difference between flying over land/pavement/continent and over water at daytime? A: the convective currents cause turbulent   Convective currents Convective currents cause the bumpy, turbulent air sometimes experienced when flying at lower altitudes during warmer weather.   Pavement / Land releasing heat wave […]

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 […]

Weather (WX) Radar

[Ref Safety first #22 July 2016 – 1/23] Weather (WX) Radar Principle The WX radar sent out a beam from its nose. The beam is converging from the transmitter at the nose. Weather detection of weather radar is based on the reflectivity of water droplets. The weather radar display depends on signal returns. The detection result – “echo” – appears on the Navigation […]

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. […]

Turbulence v.s Windshear

[Ref HKO, AC 00-6B] (Last Update : 2020 Apr 26 1422Z) Turbulence is caused by rapid, irregular motion of the air / aircraft ; Windshear is a sustained change (i.e. lasting more than a few seconds) in headwind or tailwind resulting in changes in the lift to the aircraft. Turbulence is caused by rapid, irregular […]