If OAT increases whilst maintaining a constant CAS and flight level ?
Attestation > AIM
Source: Telepilote theorique examen 44
If OAT decreases whilst maintaining a constant CAS and flight level ?
The ADC uses the following parameters as input data ?
The total pressure head comprises a mast which moves its port to a distance from aircraft skin in order To locate it outside boundary layer. if oat decreases density increases (with lower temperature air contracting density increased) cas = 1/2 x density x tas² cas constant density increases then tas must decrease mach = tas / local speed of sound local speed of sound varies only with temperature (lss varies with square root of absolute temperature formula lss = 39 x square root of (oat+273)) thus if tas decreases lss decreases mach number remains constant. 
In case of static blockage airspeed indicator Under reads in climb over reads in descent. the asi a sensitive differential pressure gauge which measures promptly indicates difference between pitot (total pressure) static pressure (total pressure static pressure = dynamic pressure) these two pressures are equal when aircraft parked on ground in calm air when aircraft moves through air pressure on pitot line becomes greater than pressure in static lines this difference in pressure registered the airspeed pointer on face of instrument thus while descending total pressure increases* the static pressure (from static source) does not your airspeed indicator will over read *while descending density increases so total pressure increases while climbing total pressure decreases the static pressure (from static source) does not your airspeed indicator will under read. 
The machmeter subject to position error this error concerns Pitot tubes static ports. the alternate static vent of an unpressurised aircraft senses air pressure in flight deck/cockpit in flight air outside flight deck accelerates over aircraft canopy (venturi effect) this causes a drop in static pressure air will always flow from a high pressure to a low pressure so air in flight deck flows outside this flow to outside causes pressure in cabin to be lower than undisturbed static pressure around aircraft. 
Given pt total pressureps static pressurepd dynamic pressurethe airspeed indicator measures Pitot tubes static ports. the alternate static vent of an unpressurised aircraft senses air pressure in flight deck/cockpit in flight air outside flight deck accelerates over aircraft canopy (venturi effect) this causes a drop in static pressure air will always flow from a high pressure to a low pressure so air in flight deck flows outside this flow to outside causes pressure in cabin to be lower than undisturbed static pressure around aircraft. Question 44-8
The open ended tube parallel to longitudinal axis of aircraft senses Pitot tubes static ports. the alternate static vent of an unpressurised aircraft senses air pressure in flight deck/cockpit in flight air outside flight deck accelerates over aircraft canopy (venturi effect) this causes a drop in static pressure air will always flow from a high pressure to a low pressure so air in flight deck flows outside this flow to outside causes pressure in cabin to be lower than undisturbed static pressure around aircraft. Question 44-9
The altimeter subject to static pressure error this error varies according to Pitot tubes static ports. the alternate static vent of an unpressurised aircraft senses air pressure in flight deck/cockpit in flight air outside flight deck accelerates over aircraft canopy (venturi effect) this causes a drop in static pressure air will always flow from a high pressure to a low pressure so air in flight deck flows outside this flow to outside causes pressure in cabin to be lower than undisturbed static pressure around aircraft. Question 44-10
The machmeter subject to position error this error varies according to Pitot tubes static ports. the alternate static vent of an unpressurised aircraft senses air pressure in flight deck/cockpit in flight air outside flight deck accelerates over aircraft canopy (venturi effect) this causes a drop in static pressure air will always flow from a high pressure to a low pressure so air in flight deck flows outside this flow to outside causes pressure in cabin to be lower than undisturbed static pressure around aircraft. Question 44-11
When climbing at a constant cas in standard atmosphere Pitot tubes static ports. for those questions use very simple 'ertm' diagram the cas line vertical because question states climbing at a constant cas ertm e as/r as(rectified air speed or cas)/t as/m ach. Question 44-12
The compressibility error must be taken into account only aeroplane with Tas greater than approximately 2 kt. for those questions use very simple 'ertm' diagram the cas line vertical because question states climbing at a constant cas ertm e as/r as(rectified air speed or cas)/t as/m ach. Question 44-13
An aeroplane flying at fl300 and mach number 0 76 the indicated total air temperature 19°c considering that probe recovery coefficient 0 96 oat Tas greater than approximately 2 kt. Revised ecqb03 july 2016 the total temperature can be expressed approximately the formula tt = ts (1 + 0 2 kr m²) ts static temperature (sat) in kelvin tt total temperature (tat) in kelvin kr recovery coefficient m mach number 254 15 = ts (1 + 0 2 kr m²) ts = 254 15 / (1 + 0 2 x 0 96 x 0 5776) ts = 254 15 / 1 11 = 229° k oat = 273 15 229 = 44 15°c at fl300 isa temperature is 15°c (2°c x 30) = 45°c we can say that oat standard. Question 44-14
The alternate static source of a light non pressurized aeroplane located in flight deck when used altimeter Tas greater than approximately 2 kt. the alternate static vent of an unpressurised aircraft senses air pressure in flight deck/cockpit in flight air outside flight deck accelerates over aircraft canopy (venturi effect) this causes a drop in static pressure air will always flow from a high pressure to a low pressure so air in flight deck flows outside this flow to outside causes pressure in cabin to be lower than undisturbed static pressure around aircraft the altimeter will sense a lower pressure than outside pressure it will tend to over read. Question 44-15
The alternate static source of a light non pressurized aeroplane located in flight deck when used The airspeed indicator tends to over read. the alternate static vent of a unpressurised aircraft senses air pressure in flight deck/cockpit in flight air outside flight deck accelerates over aircraft canopy (venturi effect) this causes a drop in static pressure air will always flow from a high pressure to a low pressure so air in flight deck flows outside this flow to outside causes pressure in cabin to be lower than undisturbed static pressure around aircraft. Question 44-16
An airplane flying at fl140 with a cas of 260 kt in standard conditions the mach number The airspeed indicator tends to over read. isa temperature at fl140 13°c on nav computer find tas next step find mach number jripoche tas=ias+2%/1000ft=332 8kt oat= 12 72°c=260 43°k mn=332 8/(38 94sqrt260 43)=0 5295 so most accurate answer shouldn't be 0 53 ? cas = ias in absence of position instrument errors you can't say cas = ias without those informations. Question 44-17
An aeroplane flying at fl300 with a tas of 470 kt in standard conditions the mach number The airspeed indicator tends to over read. in standard conditions at fl300 temperature 15°c (30 x 2°c) = 45° set 45° in airpseed window in front of 'm kt' indicator read in inner scale in front of 470 kt a mach number of 0 805. Question 44-18
During a climb at a constant cas below tropopause in standard atmosphere The mach number increases the speed of sound decreases. for those questions use very simple 'ertm' diagram the cas line vertical because question states climbing at a constant cas ertm e as/r as(rectified air speed or cas)/t as/m ach the velocity of sound decreasing as temperature decreases mach number = tas / local sound speed. Question 44-19
A servo assisted altimeter more accurate than a simple altimeter because small movements of The capsules are detected a very sensitive electro magnetic pick off. for those questions use very simple 'ertm' diagram the cas line vertical because question states climbing at a constant cas ertm e as/r as(rectified air speed or cas)/t as/m ach the velocity of sound decreasing as temperature decreases mach number = tas / local sound speed. Question 44-20
An aeroplane flying at fl100 and mach number 0 76 the indicated total air temperature 19°c considering that probe recovery coefficient 0 96 oat The capsules are detected a very sensitive electro magnetic pick off. the total temperature can be expressed approximately the formula tt = ts (1 + 0 2 kr m²) ts static temperature (sat) in kelvin tt total temperature (tat) in kelvin kr recovery coefficient m mach number 254 15 = ts (1 + 0 2 kr m²) ts = 254 15 / (1 + 0 2 x 0 96 x 0 5776) ts = 254 15 / 1 11 = 229° k 273 15 229 = 44 15°c. Question 44-21
Concerning pitot and static system position error varies with 1 altimeter setting2 mach number3 angle of attackthe combination that regroups all of correct statements The capsules are detected a very sensitive electro magnetic pick off. Cqb15 may 2012 this question exists (n°626) in database with static pressure error varies instead of position error varies statement n°2 (speed) replaced here 'mach number'. Question 44-22
An aeroplane flying at fl 320 and mach number 0 79 the oat 53°c considering that probe recovery coefficient 0 96 indicated total air temperature The capsules are detected a very sensitive electro magnetic pick off. Ecqb03 july 2016 the total temperature can be expressed approximately the formula tt = ts (1 + 0 2 kr m²) ts static temperature (sat) in kelvin tt total temperature (tat) in kelvin kr recovery coefficient m mach number tt = 220°k (1 + 0 2 x 0 96 x 0 79²) tt = 220°k (1 + 0 12) tt = 246°k tt = 273 15 246 = 26 75°c. Question 44-23
Which of these statements true The probes used sat measurements have a recovery factor of 75 to 9 while probes used tat measurements have a recovery factor of around . Ecqb03 july 2016 recovery factor refers to amount of ram rise that recoverable the sensor total head thermometers typically have a recovery factor of 0 75 to 0 9 whereas rosemount temperature probe has a recovery factor of 1 0 the ram rise due to adiabatic compression for simple sat temperature sensors used on light aircraft that fly at speeds less than mach 0 2 ram rise factor does not apply the sat sensor measures actual temperature is therefore 100% efficient tat always equal to or higher than sat due to ram rise the formula's typically used are tat = sat + ram rise or tat = sat x (1 + 0 2 kr m²) where kr the recovery factor m mach number ram rise comes into effect at airspeeds greater than m 0 2 in summary sat temperature sensors are not affected ram rise whereas tat sensors are. Question 44-24
An aeroplane in a steady descend the auto throttle maintains a constant mach number if total temperature remains constant calibrated airspeed The probes used sat measurements have a recovery factor of 75 to 9 while probes used tat measurements have a recovery factor of around . Ecqb03 july 2016 recovery factor refers to amount of ram rise that recoverable the sensor total head thermometers typically have a recovery factor of 0 75 to 0 9 whereas rosemount temperature probe has a recovery factor of 1 0 the ram rise due to adiabatic compression for simple sat temperature sensors used on light aircraft that fly at speeds less than mach 0 2 ram rise factor does not apply the sat sensor measures actual temperature is therefore 100% efficient tat always equal to or higher than sat due to ram rise the formula's typically used are tat = sat + ram rise or tat = sat x (1 + 0 2 kr m²) where kr the recovery factor m mach number ram rise comes into effect at airspeeds greater than m 0 2 in summary sat temperature sensors are not affected ram rise whereas tat sensors are. Question 44-25
In a gyromagnetic compass direction of earth's magnetic field given the The probes used sat measurements have a recovery factor of 75 to 9 while probes used tat measurements have a recovery factor of around . A flux valve a sensitive detector that receives an electrical signal from earth's magnetic field directs it to an amplifier then into a gyro stabilized compass indicator. Question 44-26
The magnetic heading can be derived from true heading means of a Map showing isogonal lines. isogonic lines connect positions that have same variation agonic line a line which joins all points where value of magnetic variation zero magnetic heading the direction that aircraft pointing in relation to magnetic north true heading the direction that aircraft pointing in relation to true north since true north (directly over earth's axis of rotation) magnetic north (somewhere over northern canada) are not at same place both headings often differ to find out difference at a particular location look at isogonic lines on your area (the lines labeled 20°e 15°e 10°e etc ) they will indicate magnetic deviation to get true heading simply take reading from magnetic compass either add an easterly or subtract a westerly magnetic deviation. Question 44-27
The fields affecting a magnetic compass originate from 1 magnetic masses 2 ferrous metal masses 3 non ferrous metal masses 4 electrical currents the combination regrouping all correct statements Map showing isogonal lines. isogonic lines connect positions that have same variation agonic line a line which joins all points where value of magnetic variation zero magnetic heading the direction that aircraft pointing in relation to magnetic north true heading the direction that aircraft pointing in relation to true north since true north (directly over earth's axis of rotation) magnetic north (somewhere over northern canada) are not at same place both headings often differ to find out difference at a particular location look at isogonic lines on your area (the lines labeled 20°e 15°e 10°e etc ) they will indicate magnetic deviation to get true heading simply take reading from magnetic compass either add an easterly or subtract a westerly magnetic deviation. Question 44-28
The input signal of amplifier of gyromagnetic compass resetting device originates from Map showing isogonal lines. The flux valve sends a signal containing information on earth's magnetic field but not at this stage carrying any information about 'error' between compass display and aircraft heading the 'error' detected at selsyn with its 'error detector' the selsyn now sends information on error to amplfier precession systems that reduce error to zero selsyn (or synchro) an electro mechanical device used the easy precise transmission of angular data between two or more remote points. Question 44-29
In gyromagnetic compass heading information from flux valve sent to Map showing isogonal lines. The flux valve sends a signal containing information on earth's magnetic field but not at this stage carrying any information about 'error' between compass display and aircraft heading the 'error' detected at selsyn with its 'error detector' the selsyn now sends information on error to amplfier precession systems that reduce error to zero selsyn (or synchro) an electro mechanical device used the easy precise transmission of angular data between two or more remote points. Question 44-30
The gyromagnetic compass torque motor Causes directional gyro unit to precess. The flux valve sends a signal containing information on earth's magnetic field but not at this stage carrying any information about 'error' between compass display and aircraft heading the 'error' detected at selsyn with its 'error detector' the selsyn now sends information on error to amplfier precession systems that reduce error to zero selsyn (or synchro) an electro mechanical device used the easy precise transmission of angular data between two or more remote points. Question 44-31
A pilot wishes to turn left on to a southerly heading with 20° bank at a latitude of 20° north using a direct reading compass in order to achieve this he must stop turn on an approximate heading of Causes directional gyro unit to precess. in northern hemisphere as you turn through north you must roll out early onto your required heading if you turn through south you roll out late use unos to remember this un = undershoot north os = overshoot south the value you need to overshoot or undershoot does vary with latitude (due to compass dip bank angle due to acceleration) to calculate value use this approximation formula (bank angle + latitude)/2 (20°bank + 20°latitude)/2 = 20° 180° 20° = 160°. Question 44-32
A pilot wishes to turn left on to a northerly heading with 10° bank at a latitude of 50° north using a direct reading compass in order to achieve this he must stop turn on an approximate heading of Causes directional gyro unit to precess. in northern hemisphere as you turn through north you must roll out early onto your required heading if you turn through south you roll out late use unos to remember this un = undershoot north os = overshoot south the value you need to overshoot or undershoot does vary with latitude (due to compass dip bank angle due to acceleration) to calculate value use this approximation formula (bank angle + latitude)/2 (10°bank + 50°latitude)/2 = 30° 000° 30° = 030°. Question 44-33
A gyromagnetic compass a system which always consists of 1 a horizontal axis gyro 2 a vertical axis gyro 3 an earth's magnetic field detector 4 an erection mechanism to maintain gyro axis horizontal 5 a torque motor to make gyro precess in azimuth the combination regrouping all correct statements Causes directional gyro unit to precess. in northern hemisphere as you turn through north you must roll out early onto your required heading if you turn through south you roll out late use unos to remember this un = undershoot north os = overshoot south the value you need to overshoot or undershoot does vary with latitude (due to compass dip bank angle due to acceleration) to calculate value use this approximation formula (bank angle + latitude)/2 (10°bank + 50°latitude)/2 = 30° 000° 30° = 030°. Question 44-34
In a gyromagnetic compass flux valve feeds Causes directional gyro unit to precess. the gyro magnetic compass made up of a magnetic detector unit (flux valve) which electrically senses direction of earth's magnetic field a gyroscope which points to a fixed point in space regardless of any manoeuvres aircraft makes an error detector to sense any difference between gyro magnetic headings apply corrections to gyro the magnetic detector unit (flux valve) feeds error detector with information about earth's magnetic field. Question 44-35
The operating principle of vertical speed indicator vsi based on measurement of rate of change of Causes directional gyro unit to precess. the gyro magnetic compass made up of a magnetic detector unit (flux valve) which electrically senses direction of earth's magnetic field a gyroscope which points to a fixed point in space regardless of any manoeuvres aircraft makes an error detector to sense any difference between gyro magnetic headings apply corrections to gyro the magnetic detector unit (flux valve) feeds error detector with information about earth's magnetic field. Question 44-36
A pilot wishes to turn right through 90° on to north at rate 2 at latitude of 40 north using a direct reading compass in order to achieve this turn should be stopped on an indicated heading of approximately Causes directional gyro unit to precess. in northern hemisphere as you turn through north you must roll out early onto your required heading if you turn through south you roll out late use unos to remember this un = undershoot north os = overshoot south the value you need to overshoot or undershoot does vary with latitude (due to compass dip bank angle due to acceleration) only 330° an undershoot value when you perform a right turn to north. Question 44-37
An aircraft takes off on a runway with an alignment of 045° the compass made the northern hemisphere during rolling take off compass indicates Causes directional gyro unit to precess. Acceleration/deceleration errors are false compass indications of a swing to north or south during speed changes of airplane this error most pronounced when flying on a heading of east or west decreases when flying closer to a north or south heading in a direct north or south heading this error does not occur in northern hemisphere compass swings towards north during acceleration towards south during deceleration in southern hemisphere this error occurs other way round when speed stabilises error disappears learn this for northern hemisphere ands ! a cceleration gives apparent turn to n orth d eceleration gives apparent turn to s outh. Question 44-38
In northern hemisphere during deceleration following a landing in a northerly direction a direct reading magnetic compass indicates Causes directional gyro unit to precess. Acceleration/deceleration errors are false compass indications of a swing to north or south during speed changes of airplane this error most pronounced when flying on a heading of east or west decreases when flying closer to a north or south heading in a direct north or south heading this error does not occur in northern hemisphere compass swings towards north during acceleration towards south during deceleration in southern hemisphere this error occurs other way round when speed stabilises error disappears learn this for northern hemisphere ands ! a cceleration gives apparent turn to n orth d eceleration gives apparent turn to s outh. Question 44-39
In northern hemisphere during deceleration following a landing in a southerly direction a direct reading magnetic compass indicates Causes directional gyro unit to precess. Acceleration/deceleration errors are false compass indications of a swing to north or south during speed changes of airplane this error most pronounced when flying on a heading of east or west decreases when flying closer to a north or south heading in a direct north or south heading this error does not occur in northern hemisphere compass swings towards north during acceleration towards south during deceleration in southern hemisphere this error occurs other way round when speed stabilises error disappears learn this for northern hemisphere ands ! a cceleration gives apparent turn to n orth d eceleration gives apparent turn to s outh. Question 44-40
During deceleration following a landing in a westerly direction a magnetic compass made the northern hemisphere indicates An apparent turn to south. Acceleration/deceleration errors are false compass indications of a swing to north or south during speed changes of airplane this error most pronounced when flying on a heading of east or west decreases when flying closer to a north or south heading in a direct north or south heading this error does not occur in northern hemisphere compass swings towards north during acceleration towards south during deceleration in southern hemisphere this error occurs other way round when speed stabilises error disappears learn this for northern hemisphere ands ! a cceleration gives apparent turn to n orth d eceleration gives apparent turn to s outh.
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