Instrumentation Flashcards
Mnemonic for blocked pitot or static error on ASI
PUDSOD
Pitot blocked => Underread in descent
Static blocked => Overread in descent
Mnemonic for IAS, CAS, EAS, TAS and corrections
ICE T & Pussy Cat Dolls
I: IAS - correct by P: Position error to get
C: CAS - correct by C: Compressibility…
E: EAS - correct by D: Density…
T: TAS
Correction on magnetic compass when turning through N/S in NH
- Mnemonic
- Calculation
UNOS
UnderSHOOT turning through North
OverSHOOT turning through South
(i.e. when turning through north, stop before you reach the target heading, through south, go past target heading)
Amount to x-shoot: (Lat + bank angle) / 2
Correction on magnetic compass when accelerating in W/E direction in NH
ANDS
Accelerating - shows turn to north
Decelerating - shows turn to south
[Accelerate shows turn to nearer pole]
Directional gyro - orientation
Directional gyros are horizontal gyros, i.e. spin axis is horizontal, the rotor spins in the vertical plane.
The rotor axis lies in the yawing plane.
Directional gyro
- Degrees of freedom (and which planes)
2 degrees of freedom (2 gimbals)
Free in pitch and roll (but not yaw, which is what we are measuring)
Artificial horizon gyro
- Orientation (Horizontal or vertical)
- Type
Vertical gyro (spin axis is vertical, rotor spins in horizontal plane).
Earth Gyro type (sub-type of tied gyro).
Rate of Turn Indicator construction
Horizontal axis gyro has one degree of freedom so that if the aircraft banks it remains horizontal. If the aircraft turns (yaws) however, the force of the gyro being turned is precessed to a “banking” force, which is opposed by springs. The force of the spring creates a secondary precession opposing the rate of turn of the aircraft.
The secondary precession is measured to assess rate of turn.
Turn-coordinator differences to rate of turn indicator
Turn coordinator gyroscope is mounted with axis at 30 degrees to the aircraft longitudinal axis making it sensitive to banking as well as turning.
The coordinator responds to bank first to give a correct initial turn direction indication, but balances out correctly with rate of turn due to springs.
Weakness of turn coordinator
Sensitivity to yaw & roll (even pitch if TAS is wrong) makes it sensitive to TAS. Only rate 1 turn at designed TAS will be accurate (maybe within about 5% of design TAS).
CDI: Meaning of to/from indications
Tell you whether maintaining the selected course takes you TO or FROM the beacon, NOT related to radials.
RMI
Radio Magnetic Indicator
Combination directional indicator (driven by remote compass) and VOR/radio indicator.
Card rotates so that heading is at the top, a bug can be set and a green arrow will sit on top pointing to the radio bearing.
Horizontal Situation Indicator
RMI with additional VOR deviation markings across the middle
FMS, EFIS & CDU
FMS - Flight Management System (the software)
EFIS - Electronic Flight Information System (display unit of FMS info)
CDU - Control Display Unit (panel to manage FMS, 1 per pilot)
Navigation Display (ND)
- Magnetic or True North orientation?
Default is magnetic between around 60 or 65 S to 73N, true outside that band.
However it can be manually overridden in general.
ND
- Deviation from target per dot in VOR and ILS modes
2 dots either side of target
VOR: 5 degrees each dot (20 degrees covered in total)
ILS: 1.25 degrees each dot (5 degrees covered in total)
ND
- Weather radar colouring
In mm/hour
Black: 0-1
Green: 1-4
Yellow: 4-12
Red: 12-50
Magenta: 50+ (Or doppler turbulence in TURB mode)
GPWS modes
Mode 1: Sink rate
Mode 2: Ground proximity
Mode 3: Altitude loss after TO or GA
Mode 4: Incorrect landing configuration
Mode 5: Below glidescope deviation
GPWS
- Alerts and warnings by mode
EGPWS/TAWS
- How it works
- 3 tools it provides
Uses position fix (needs to be accurate) and a database of terrain (more detailed near airports).
Provides:
1) Terrain clearance floor (based on 3 degree approach around NEAREST airport)
2) Terrain look ahead alerting
3) Terrain Alerting and Display (similar display to weather radar)
Flight warning system priority
- GPWS
- TCAS
- Stall
- Windshear
1) Stall
2) Windshear
3) GPWS
4) TCAS
ASI zones
- White
- Green
- Yellow/Amber
White: Flaps extended range, V(S0) to V(FE)
Green: Flaps up normal range, V(S1) to V(NO)
Yellow: Caution range, V(NO) to V(NE)
Type of drift caused by instrument error
Real Wander
