Airspeed Indicator Flashcards
(23 cards)
What is the conversion for kt to Mph to Kph?
1kt = 1.15mph = 1.85kph
What does a blue line indicate on a ASI?
Best rate of climb OEI on a light twin
What does a lower red line indicate on a light twin ASI?
Vmca
What happens when an aircraft decelerates?
Pitot pressure decreases, pressure capsules contract, needle decreases
What happens when an aircraft accelerates?
Pitot pressure increases, pressure capsules expand, needle increases
How is an ASI calibrated?
To ISA sea level conditions
What happens to the TAS reading as altitude increases?
ASI under reads due to density error
What is unreliable airspeed?
Abnormally large MN or IAS fluctuations and differences between the indications at each pilot position or between target and actual speed
How can we recognise unreliable airspeed?
- Unusual attitude
- Buffeting or unexpected aircraft behaviour
- Aerodynamic warning system may also alert pilot
What speed does GPS provide?
Ground speed
What is clock error?
The clock on the GPS receiver might not be as accurate as the atomic clock on the GPS satellite
What is orbital error?
Orbit calculations can be inaccurate, causing ambiguity in determine the satellites exact location
What is GPS position error?
GPS signals can bounce off buildings and terrain and rely on line of sight
What is GPS climb error?
GPS only calculate ground speed, therefore speed in climb and descent will not be reflective of the aircrafts actual speed
What are 3 unreliable airspeed countermeasures?
- Check power set
- Pitch and speed are interchangeable
- Wind noise in a light aircraft (noisy = fast)
What are the ASI errors?
I - instrument
M - manoeuvre
P - position
Compressibility
Density
What is ASI compressibility error?
Only applicable at speeds over 300kts due to compression of air
What is ASI density error?
Due to variations in altitude and temperature from the ISA model
What is the pneumonic for airspeeds and errors?
ICE T Is Pretty Cool Drink
What are the ASI blockage errors?
SOD PUD
SUC POC
What does the ASI indicate when there is a leak within the pitot line?
Pitot pressure reduces, ASI will under-read
What does the ASI indicate when there is a leak within the pressure hull?
ASI will under read
What does the ASI indicate when there is a leak outside the pressure hull?
Slight over read
