Instruments Flashcards
(30 cards)
What happens to the altimeter in a non-pressurized aircraft using an alternate static port?
Altimeter Overreads (indicates higher than actual)
The alternate static source often senses a slightly lower static pressure than ambient due to aerodynamic suction in the cabin.
What is the effect on the altimeter if the left static port is blocked and the aircraft is in left sideslip?
Overreads altitude
The opposite occurs if the right static port is blocked during right sideslip.
What occurs when the altimeter is not compensated for position error at higher speeds?
Tends to Underread (indicate a lower altitude)
Airflow distortion around static ports or pitot tube creates a pressure error that is not compensated.
What happens to the altimeter once the static source is blocked during climb or descent?
No Change in indicated altitude after blockage (altimeter reading becomes fixed/frozen)
The altimeter effectively freezes at the pressure level where the blockage occurred.
How does temperature affect altimeter readings when moving from warm to cold air?
Altimeter Overreads (indicates higher than actual)
Pressure levels contract when moving into colder air.
What is the mnemonic to remember the effect of temperature changes on altimeter readings?
‘From high to low, look out below; from low to high, clear the sky.’
What effect does opening the alternate static source have on the VSI in a non-pressurized aircraft?
Momentary climb indication
Due to pressure difference.
What happens to the VSI if the pitot tube is partially blocked?
Indicates too low when descending, too high when climbing
This occurs due to incorrect dynamic pressure sensing.
What is the effect on VSI readings when the static port is partially blocked?
Indicates too low when climbing or descending
Blocked static source affects pressure readings.
What happens to VSI when the choke is partially blocked?
Indicates too high when climbing or descending
A restriction in airflow causes this effect.
What is required if the static vent is blocked in an unpressurized aircraft?
Requires alternate static source
This is necessary to provide accurate static pressure.
What indicates too high when climbing and too low when descending in a pressurized aircraft?
VSI casing leak
A casing leak affects internal pressure readings.
How does a partially blocked static pipe affect VSI during descent?
Indicates too low when descending
This is due to restricted static pressure flow.
What is the effect on VSI readings if the pitot tube is partially blocked?
Unaffected
Pitot tube does not directly impact VSI readings.
What happens to the ASI if the total pressure probe is blocked during climb?
Airspeed steadily increases
A blocked pitot probe causes this steady increase.
What effect does a blocked pitot probe have on the ASI during descent?
Airspeed indicator will indicate decreasing speed
This occurs as the airspeed steadily decreases.
What happens to the ASI when the static source is blocked?
ASI overreads during descent, underreads during climb
The blockage causes these reading discrepancies.
What occurs when both the pitot tube and drain hole are blocked while the static port is open?
ASI will act like an altimeter
It responds only to altitude changes.
What happens when the pitot tube leaks and the pitot drains are blocked in an unpressurized aircraft?
ASI will overindicate
This occurs due to no impact on the pitot.
What is the effect on ASI when both the static tube and drain are blocked?
ASI over/underreads depending on altitude
This leads to altitude-dependent errors.
What effect does using an alternate static source have on ASI in a non-pressurized aircraft?
ASI overreads
This is due to lower static pressure sensing.
What is the effect of a blocked pitot probe on airspeed indication?
Airspeed indication affected by pitot blockage
This leads to incorrect airspeed readings.
What happens if the drain hole and pitot are blocked while the static source is open?
ASI behaves like an altimeter
It responds only to altitude changes.
What is the reading of ASI during descent if both the pitot source and drain are blocked?
ASI underreads during descent
This occurs due to the blockage.
