Explain the different in pressure between static air and air in motion
Air in motion exerts dynamic pressure. Static air exerts static pressure all around
What is the purpose of the pitot tube?
To measure ram air pressure (dynamic pressure due to forward motion)
What is the purpose of the static port?
To measure static or ambient air pressure through ports placed parallel to the relative airflow
How does the static port affect air pressure?
It allows air pressure inside the instruments to become equal with the air pressure outside the cases
What should be done in an emergency for an aircraft not equipped with an alternate static source?
Break the face glass of the VSI to provide static pressure from the cabin
Describe the set up of the pilot static system
Describe the VSI, ASI, and ALT readings when a pitot or static blockage occurs
When is pitot heat used?
Anytime ice is suspected in the pitot tube. The ice could create erroneous or no readings on the ASI
An aircraft is not in motion. What is the ASI reading?
In what unit does the ASI display airspeed?
knots or miles per hour
How does the ASI measure airspeed?
By measuring the difference between dynamic and static pressure. The larger the difference, the higher the reading
Describe the different ASI markings
Red line: VNE (never exceed)
Yellow arc: VNO - VNE (caution range)
Green arc: VS1 - VNO (normal operating range)
White arc: VSO - VFE (flap operating range)
List the causes of ASI errors
Position error (angle of attack)
Compressibility error (250kts+)
Density error (temperature, pressure)
What kind of instrument is the VSI? What does it display?
A trend instrument that displays the rate of climb or descent
Describe the set up of an aneroid barometer
List three things to do doing a VSI serviceability check
Check if VSI reads 0 on the ground
Check static port clean
Check alternate static source (VSI should jump)
What is the standard international atmosphere?
- Perfectly dry gas
- Surface pressure of 29.92" Hg
- Lapse rate of 2°C/1000' within troposphere
- Weight of column of air is 14.7lbs
Describe the purpose of the altimeter. When does it work properly?
Indicates correct altitude above sea level when conditions of temperature and pressure are those of the ISA
Describe what happens to the altimeter readins when pressure varies along the route
What happens to the altimeter reading if temperature is standard? Why is this dangerous?
Error in reading. This is dangerous because extreme variations in temperature may cause a 2500' difference in indicated altitude
Describe the affect of nonstandard temperature and pressure on actual and indicated altitude
Where does a mountain wave form?
Where wind faster than 50 knots blows within 30 degrees of the perpendicular to the main axis of the mountain range
How far can the effect of a mountain wave extend?
As far as 100 miles downward of the moutains to altitudes many times higher than the mountain elevation
Describe the pre flight altimeter serviceability check
Must read within +/- 50' of the field elevation
Static source checked clean and clear
Alternative static source checked (ALT should jump)
How often should the pilot static system and altimeter be calibrated for IFR flight?
Every 24 months
What should you do if you have no altimeter setting available at the aerodrome?
Adjust the altimeter setting knob to the known field elevation until the altimeter indicates that same elevation
What is an advantage of the encoding altimeter?
Aircraft can be 3D identified by ATC
Define the magnetic meridian and magnetic variation
Magnetic meridian - magnetic line in which in the compass needle lies in
Magnetic variation - angle between the true meridian and magnetic meridian
List sources of compass error
Magnetic dip, deviation, turning error, acceleration error
What is a cause of compass deviation? How can deviation from the magnetic meridian be determined?
The compass can be influenced by the aircraft's metal frame, the engine, or electrical devices. Deviation can be determined by swinging the compass