Lesson 5 Questions Flashcards
How many errors does the magnetic compass have? Describe.
- Variation
- — the difference between true and magnetic directions
- Deviation
- — local magnetic fields in an aircraft caused by electrical current flowing in the structure conflicting with the Earth’s magnetic field
- Northerly-Turning Errors
- — If on a north heading and a turn is started to the east or west, the compass indication lags or indicates a turn in the opposite direction.
- Southerly-Turning Errors
- — If on a south heading and a turn is started toward the east or west, the compass indication precedes the turn, indicating a greater amount of turn than is actually occurring.
- Acceleration Error
- — If on an east or west heading, acceleration results in a north turn indication; deceleration results in a south turn indication (ANDS - Acceleration NORTH | Deceleration SOUTH).
- Oscillation Error
- — combination of all the other errors and results in the compass card swinging back and forth around the actual heading being flown
Explain ‘East is least, West is best.’
You SUBTRACT EASTERLY variation from your true course to get your magnetic course, and you ADD WESTERLY variation from your true course to get your magnetic course.
Our variation is about 2ºW, so in our area, we would add 2º to our true course to get our magnetic course.
Explain the following: Variation, Deviation, Compass Heading, A N D S, U N O S.
Variation: difference between true north and magnetic north
Deviation: interference caused by magnetic fields running through instruments/equipment in the airplane
Compass Heading: The heading flown on the magnetic compass after corrections for deviation are applied
ANDS (true in the NORTHERN hemisphere): Acceleration North, Deceleration South - If on an east or west heading, acceleration results in a northerly turning indication and deceleration results in a southerly turning indication
UNOS: Undershoot North, Overshoot South - In the NORTHERN hemisphere, UNDERshoot your heading. In the SOUTHERN hemisphere, OVERshoot your heading.
On what heading is acceleration/deceleration error most pronounced?
These errors are most pronounced on east/west headings.
When would you perform a timed turn?
Timed turns are used primarily when controlling the aircraft with a loss of the heading indicator (AHRS/magnetometer failure in glass cockpit)
What instruments are used when performing a timed turn?
Clock/timer, magnetic compass, turn rate indicator.
In a timed turn, what instruments are primary for bank, pitch, and power?
Primary pitch instrument is the ALTIMETER, primary power instrument is the ASI, primary bank instrument is the turn rate indicator.
Why is it important to check the accuracy of your turn coordinator before attempting a timed turn?
If you are not actually turning at a rate of 3º per second when referencing your turn coordinator, your turns will not be accurate and you will not roll out on the correct heading.
When performing a compass turn, is it necessary to lead or lag when turning to a northwest heading? Why?
Since the compass LAGS (shows a turn to the opposite direction) when turning from north to northwest, it’s necessary to roll out PAST our desired heading.
What should be your first response to a vacuum failure?
Remove the failed instruments from your scan (try to cover it with something if possible), use alternative instruments for pitch/bank information.
Pitch Instruments:
- Airspeed Indicator
- Vertical Speed Indicator
- Altimeter
Bank Instruments:
- Heading Indicator
- Turn Coordinator
- Magnetic Compass
What should be your first response to a vacuum failure?
Remove the failed instruments from your scan (try to cover it with something if possible), use alternative instruments for pitch/bank information.
Pitch Instruments:
- Airspeed Indicator
- Vertical Speed Indicator
- Altimeter
Bank Instruments:
- Heading Indicator
- Turn Coordinator
- Magnetic Compass
At standard rate, how many seconds will it take to turn 180°?
60 seconds
True/False: The maximum ACS altitude deviation while performing timed turns is ±200 feet?
I think it’s ±100 feet?
Describe the components of the magnetic compass.
The magnetic compass has two small magnets attached to a metal float inside of a bowl of clear compass fluid (similar to kerosene). A card is wrapped around the float and viewed through a glass window.
How does the magnetic compass work?
The magnets align with the Earth’s magnetic field and the pilot reads the direction. The pilot is always viewing the card from its backside so the compass appears to turn the “wrong” way.
