The Airspeed Indicator Flashcards
The ASI is calibrated to what standard?
The international standard atmosphere
At what conditions does CAS = TAS?
When the atmosphere is at the ISA conditions
When flying faster than TAS 300, compressibility starts to affect the IAS. Does this effect cause the ASI to over-read or under-read?
Over-read
CAS corrected for compressibility error = ?
EAS (equivalent airspeed)
IAS +/- position and instrument error = ?
CAS
CAS +/- density error = ?
TAS (may have compressibility error)
CAS - compressibility error = ?
EAS
EAS +/- density error = ?
TAS
The ASI indicates the last recorded airspeed, the problem is?
The pitot head is blocked, maintaining the last recorded pressure. If there is a leak in the pressure line the airspeed will drop to zero.
What will occur of the static source becomes blocked in level flight?
The ASI will indicate normally, assuming no change in static pressure.
The mnemonic to remember blockages effects while climbing and descending?
CPO = Climbing - Pitot(blocked) - Over-read
CSU = Climbing - Static(blocked) - Under-read
DPU - Descending - Pitot(blocked) - under-read
DSO - Descending - Static - Over-read
What does the lowest point of the white arc represent?
Vso, the stalling speed with full flaps extended.
What does the highest point of the white arc represent?
Vfe, maximum speed with flap extended.
What does the lowest point of the green arc represent?
Vs1, the stalling speed with flaps up.
What does the highest point of the green arc represent?
The maximum normal operating range (Vno)
What does the blue line on a multi-engined ASI represent?
Vyse, the best rate of climb with one engine inoperative
To compensate for the contraction and expansion of the linkage system due temperature changes, the ASI linkage system includes?
A Bi-metallic strip
Manoeuvre induced error is caused by?
Changes of aircraft attitude or when the pitot head is not aligned with the airflow(climb or descent). It is also due to changes of aircraft configuration, flap operation or landing gear being lowered etc. The error is random and no compensation can be made
The type of error that is random and also cannot allow for compensation is?
Manoeuvre induced error
At TAS 300+ compressibility causes the ASI to?
Overread
What If the pitot head becomes blocked in level flight?
The Pitot pressure line and capsule will hold the pressure and the ASI reading will be maintained at the last recorded airspeed regardless of any power and airspeed change.
What If the static line becomes blocked in level flight?
The ASI will read correctly assuming no change in static pressure.
what if the pitot line from the pitot head to the ASI leaks?
The ASI will underread since the dynamic pressure is too low
VS1 is?
The stalling speed with flaps up
VSO is?
Stalling speed in the landing configuration
Remembering TAS, CAS and IAS:
ICETPCD
(Ice tea preferred cold drink)
=
ICET = IAS, CAS, EAS and TAS:
PCD = Position/instrument error, Compressibility, Density:
IAS + P = CAS
CAS + C = EAS
EAS + D = TAS
The indicated Mach number is independent of:
temperature
TAS increases:
With altitude and temperature
CAS =
rho squared x TAS
CAS = TAS at -
ISA temperature, any temperature above ISA the ASI will underread. This is called density error, and is rectified by using TAS.
