Flight Instruments, Failures, & Emergencies Flashcards
What instruments operate on the Pitot-Static System?
- Airspeed Indicator
- Altimeter
- Vertical Speed Indicator
What instrument relies on the Pitot tube?
The Airspeed Indicator
How does an Altimeter work?
- An Altimeter senses the difference between the pressure set to 29.92 in HG in the aneroid wafer and the outside air pressure fed into the chamber surrounding the wafer.
- The wafer is attached to a series of gears and linkages to the needle on the instruments display
What errors are associated with the Altimeter?
- Non-Standard temperature errors
- Non-Standard pressure errors
Explain the temperature errors associated with the Altimeter.
Warmer than standard temps
- Warm air is less dense
- Pressure levels are higher for a given altitude than they would be at standard temps
- True Altitude (MSL) is higher than Indicated
Colder than standard temps
- The air pressure is lowered
- Pressure levels are lower than they would be at standard temps
- True Altitude MSL is lower than Indicated.
- This is dangerous
Extreme Cold Temps
- It may be necessary to apply a cold temperature correction to the Altimeter to provide additional terrain/obstacle clearance
***REMEMBER: Hot to cold, look out below
What is the correlation between air Temperature and air Pressure?
They are conversely related
- High Pressure = Temp must also increase
- Low Pressure = Temp must also decrease
Explain the Pressure errors associated with the Altimeter.
If the Altimeter setting is not adjusted when flying between different areas of pressure, the reading will be incorrect
High to Low Pressure
- True Altitude (MSL) will be lower than Indicated
- Dangerous
Low to High Pressure
- True Altitude (MSL) will be higher than Indicated
For IFR flight, what is the maximum allowable error for an Altimeter?
The Altimeter must read within +- 75ft of field elevation
What is Indicated Altitude?
The Altitude as read from the Altimeter
What is True Altitude?
The height above mean sea level (MSL)
Charted in MSL
- Airport elevation
- Airspace heights
- Terrain
- Obstacles
What is Absolute Altitude?
Height above the ground (AGL)
Charted in AGL
- MDA/DA in (parentheses) on an IAPs minimums
What is Pressure Altitude?
Our Altitude corrected for non-standard Pressure
- You can find it by setting the altimeter to 29.92 on the ground
- Used to compute things like Density Altitude and True Airspeed
What is Density Altitude?
Pressure Altitude corrected for non-standard Temperature
- This is the altitude the aircraft will feel like its performing at
- A high Density Altitude means that your aircrafts performance will be negatively effected (engine, climb, stall recovery)
Does adjusting your Altimeter setting have any effect on the altitude displayed to ATC?
No
How does the Airspeed Indicator work?
The airspeed indicator measures the difference between RAM air pressure from the Pitot Tube and Static air pressure from the Static ports
- Static Pressure is sent to the aneroid wafer inside the Airspeed indicator
- Total Pressure enters the Pitot Tube and is sent to the chamber surrounding the aneroid wafer