Category: ATPL Knowledge

Question: if you are a load control officer, forward CG or aft CG is better for performance?

Provided that the aircraft remain with safe envelope, in general, aft CG (load cargo at rear compartment) has better performance. An aft center of gravity position/hold loading, for aircraft (especially jet/swept wing) with a nose-up en route attitude will allow it to achieve its maximum possible range. An aft center of gravity position, normally is Read More

What’s “isogonic line” and “agonic line”?

Isogonic line: lines on chart showing the places where have same magnetic variation. Agonic line: lines on chart showing the places where magnetic variation is zero. What’s Variation, Deviation? Read More

一次搞清幾時True heading 幾時Magnetic heading

Ref https://www.casa.gov.au/resources-and-education/publications/industry-guides/pilot-guides/visual-flight-rules-guide With reference to AIP HKG GEN 2.1 With reference to AIP Australia GEN 2.1:   With reference to CASA Visual Flight Rules Guide (VFRG): Wind – ref to True: Aerodrome weather and forecast Grid point wind and temperature (GPWT) forecast Notes: also ref AIP GEN 3.50 Wind – ref to Magnetic: Aerodrome weather Read More

Magnetic Compass

Ref https://www.aviation.govt.nz/licensing-and-certification/pilots/flight-training/flight-instructor-guide/compass-use/ A magnet bar that is freely suspended horizontally will swing so that its axis points roughly north-south. The end of the magnet that points toward the earth’s north magnetic pole is called the north-seeking pole of the magnet. What’s Variation, Deviation? Read More

INS – Inertial Navigation System

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Errors on gyroscope instrument – Wander = Real Wander + Total apparent Wander

“Wander” – describe the situation when the gyroscope’s spin axis away from its fixed direction (reference datum) Due to its rigidity, the spin axis of a perfect gyro should continue to point in a fixed direction. Any movement of the spin axis away from this fixed direction is known as gyro wander. Depending on the Read More

Slip v.s Skid on Inclinometer (coordination ball)

Ref Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25C (Full Version) Chapter 5 Correct by step on the ball Ball at higher wing – skid : Tail out from turning radius – indicated by ball to higher wing Centrifugal force greater than horizontal lift Correct by reduce the ROT (rate of turn) AND/OR increase in bank   Read More

What’s gimbal in gyroscope instrument?

Ref Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25C (Full Version) Chapter 8 What’s gimbal? Ans: the component which can limits the planes in which the gyro can tilt.   Ref https://www.pilot18.com/wp-content/uploads/2017/06/2-INS-Gyro-Instruments.pdf Gyro types depend on the number of planes of freedom of movement. Freedom of movement is achieved by mounting the gyro in gimbal rings. Space Read More

Turn Coordinator (TC) vs Turn and Slip Indicator (TI)

Type of gyro used in TC and TI? Ans: Horizontal gyro – rotate around horizontal axis!   The major difference between TC and TI? The gimbal that holds the gyro in a TC is tilted for 30 degree.   Turn Coordinator:  ✔ rate of turn (yaw) ✔ roll rate (bank)   Turn Indicator:  ✔ rate Read More

Continent and Ocean

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Generator v.s Alternator

Also Ref. https://www.electricaltechnology.org/2020/05/difference-between-alternator-generator.html/amp 不要中毒太深 睇下好喇 For PPL and even CPL, basically, generator and alternator are the same thing…. Main Differences between Alternator and Generator Alternator: A machine that only converts mechanical energy into AC electrical energy. Generator: can generate either of both Alternating current AC or Direct Current “DC”. Read More

What’s International Standard Atmosphere (ISA)

Ref: https://skybrary.aero/articles/international-standard-atmosphere-isa ISA is known as the ICAO Standard Atmosphere, ISA is a standard against which to compare the actual atmosphere at any point and time. ISA condition, at mean sea level: Read More

What is the Geographic (True) North Pole?

Ref: https://gisgeography.com/magnetic-north-vs-geographic-true-pole/ The Earth rotates on the geographic north and south poles. The geographic north and south poles are where lines of longitude (meridians) converge in the north. The south and north poles are directly opposite to one another. The North Pole is located in the middle of the Arctic Ocean. Scientists have tried marking the North Pole. Read More

Otto cycle vs Brayton cycle – PV diagram

Ref: https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Thermodynamics/Thermodynamic_Cycles/Brayton_Cycle https://www.nuclear-power.com/nuclear-engineering/thermodynamics/thermodynamic-cycles/brayton-cycle-gas-turbine-engine/theory-of-brayton-cycle-brayton-engine/ https://www.mas.bg.ac.rs/_media/istrazivanje/fme/vol39/3/01_jdoric.pdf Idea gas formula: PV= nRT The typical four-stroke cycle (otto cycle) is described as a constant volume heat addition cycle. The combustion is so rapid that the piston does not move during the combustion process, and thus combustion is assumed to take place at constant volume The Brayton process is the Read More

General Aviation Oil system (wet sump v.s dry sump)

Wet sump   Dry sump Read More

Braking disc

Vocab: Corroded or pitted disc 生鏽 / 磨損左的 碟 Read More

Creep marks on wheels

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Wheel and Carcass

Vocab: Parts of wheel Rim flange barrel center disc spoke lug hole center hole   Description of carcass sidewall tread   Flat tire bulges on tire cut or scores on tire   under inflated , properly inflated , over inflated   creep detected on tire – when the creep marks are not aligned Read More

Camshaft, Crankshaft, rpm?

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What’s glide ratio?

Ref FTA material, Skybrary https://skybrary.aero/articles/glide-performance#:~:text=Description,altitude%20lost%20in%20that%20distance.     The glide ratio for the DA40 is approximately 10:1 What’s glide ratio? The Glide ratio of an aircraft is the distance of forward travel divided by the altitude lost in that distance. (It is talking about same unit~)   Below is another example: For every 1.45 NM (2.68km Read More

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