ATPL INSTRUMENTS AND NAV AIDS
EXAM QUESTIONS & ANSWERS
What is Mach number? - Correct Answers -The ratio of TAS to the LSS
Mach = TAS / LSS
If an aircraft climbs at a constant TAS, the IAS will ...... and the Mach number will .....
because .... - Correct Answers -The IAS will decrease, because to maintain TAS in
thinner air you must fly slower.
Mach number will increase as the air gets cooler, causing the LSS to reduce and
therefore increasing Mach number
If an aircraft climbs as a constant Mach number in ISA conditions about FL360, the TAS
will ..... - Correct Answers -Remain constant due to the isothermal layer
If an aircraft is flying at a constant altitude and IAS into significantly colder air the Mach
number will ..... because ..... - Correct Answers -Increase
The speed of sound slows
The Mach meter can suffer from ..... and ..... error as well as ...... ...... errors but is
unaffected by ..... or ..... error as these two ..... each other out - Correct Answers -
Instrument
Position
Manoeuvre induced
Density
Temperature
Cancel
The Machmeter in modern air transport aircraft is designed so that ...... and ..... error will
always lead to the Machmeter ...... reading - Correct Answers -Instrument
Position
Over
ASI errors which do not affect the machmeter are ...... - Correct Answers -
Compressibility and density errors
, What is the purpose of the ADC and what does it do? - Correct Answers -The ADC
converts analogue inputs to electrical signals/digital outputs and transmits them via data
buses to various flight instruments and aircraft systems
Inputs to the ADC - Correct Answers -Pitot pressure
Static pressure
TAT
Angle of Attack
Outputs from the ADC (9) - Correct Answers -Altitude
IAS/CAS
SAT
TAT
Angle of Attack
TAS
Vertical speed
Mach number
Vmo/Mmo
Errors associated with electro-mechanical ADCs are minimised by employing ..... -
Correct Answers -Correlation cams
How many ADCs are there and what happens if one has a blockage? Is there provision
for a dual failure? - Correct Answers -2
Switch to other ADC or alternate static source
No, cannot input data manually
What is recovery factor? - Correct Answers -The proportion of TAT which the sensing
element is able to detect in the air passing it
Ts = - Correct Answers -Tm/1+0.2xkxM^2
How does a fly by wire system work? - Correct Answers -It sends digital signals from
flight controls or autopilot via the flight control computers, to the control surfaces
The AFDS consists of ..... AFDCs and the ..... - Correct Answers -3
MCP
What does the AFDS control? - Correct Answers -The flight directors and the autopilot
Where is FD information displayed? - Correct Answers -PFD
Normal
Autopilot disengagement is through the ..... ..... autopilot disconnect switch - Correct
Answers -Control column
EXAM QUESTIONS & ANSWERS
What is Mach number? - Correct Answers -The ratio of TAS to the LSS
Mach = TAS / LSS
If an aircraft climbs at a constant TAS, the IAS will ...... and the Mach number will .....
because .... - Correct Answers -The IAS will decrease, because to maintain TAS in
thinner air you must fly slower.
Mach number will increase as the air gets cooler, causing the LSS to reduce and
therefore increasing Mach number
If an aircraft climbs as a constant Mach number in ISA conditions about FL360, the TAS
will ..... - Correct Answers -Remain constant due to the isothermal layer
If an aircraft is flying at a constant altitude and IAS into significantly colder air the Mach
number will ..... because ..... - Correct Answers -Increase
The speed of sound slows
The Mach meter can suffer from ..... and ..... error as well as ...... ...... errors but is
unaffected by ..... or ..... error as these two ..... each other out - Correct Answers -
Instrument
Position
Manoeuvre induced
Density
Temperature
Cancel
The Machmeter in modern air transport aircraft is designed so that ...... and ..... error will
always lead to the Machmeter ...... reading - Correct Answers -Instrument
Position
Over
ASI errors which do not affect the machmeter are ...... - Correct Answers -
Compressibility and density errors
, What is the purpose of the ADC and what does it do? - Correct Answers -The ADC
converts analogue inputs to electrical signals/digital outputs and transmits them via data
buses to various flight instruments and aircraft systems
Inputs to the ADC - Correct Answers -Pitot pressure
Static pressure
TAT
Angle of Attack
Outputs from the ADC (9) - Correct Answers -Altitude
IAS/CAS
SAT
TAT
Angle of Attack
TAS
Vertical speed
Mach number
Vmo/Mmo
Errors associated with electro-mechanical ADCs are minimised by employing ..... -
Correct Answers -Correlation cams
How many ADCs are there and what happens if one has a blockage? Is there provision
for a dual failure? - Correct Answers -2
Switch to other ADC or alternate static source
No, cannot input data manually
What is recovery factor? - Correct Answers -The proportion of TAT which the sensing
element is able to detect in the air passing it
Ts = - Correct Answers -Tm/1+0.2xkxM^2
How does a fly by wire system work? - Correct Answers -It sends digital signals from
flight controls or autopilot via the flight control computers, to the control surfaces
The AFDS consists of ..... AFDCs and the ..... - Correct Answers -3
MCP
What does the AFDS control? - Correct Answers -The flight directors and the autopilot
Where is FD information displayed? - Correct Answers -PFD
Normal
Autopilot disengagement is through the ..... ..... autopilot disconnect switch - Correct
Answers -Control column
