1. Flight Instruments Which way’s up?
Written for the Notre Dame Pilot Initiative
By the Pilots of the University of Notre Dame
“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”

2. Roadmap
Pitot-Static System
Vacuum System
Magnetic Compass

3. Flight Instruments Pitot-Static System and Instruments
Airspeed Indicator (ASI)
Vertical Speed Indicator (VSI)
Altimeter
Vacuum System and Instruments
Attitude Indicator
Heading Indicator
Turn Coordinator
Suction Gage
Magnetic
Magnetic Compass

4. Pitot-Static
“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”

5. Atmospheric Conditions
International Standard Atmosphere (ISA)
Pressure = inches Hg at sea level
Temperature = 15C (59F)
Standard Lapse Rates
Temperature lapses at 2C per 1,000 feet
Pressure lapses at 1.00 inch Hg per 1,000 feet

6. Airspeed Indicator (ASI)
V-speeds
VA = maneuvering *
VFE = flap extend
VLE = landing gear extended
VLO = landing gear operating
VNO = max structural cruising speed
VNE = never exceed speed
VR = rotation
VX = best angle *
VY = best rate *
VS = stall clean configuration
VSO = stall landing configuration
not on ASI (contained in POH)
Arcs
White
Bottom = VSO
Top = VFE
Green
Bottom = VS
Top = VNO
Yellow
Bottom = VNO
Top = VNE
Red Line = VNE

7. Types of Airspeed Indicated Airspeed (IAS) Calibrated Airspeed (CAS)
Speed indicated on ASI
Calibrated Airspeed (CAS)
IAS corrected for calibration error
Equivalent Airspeed (EAS)
CAS corrected for compressibility error
True Airspeed (TAS)
EAS corrected for density error
Altitude
Nonstandard temperature
Groundspeed (GS)
Speed over the ground
TAS adjusted for wind

8. At greater altitudes, the same volume of air contains fewer molecules of the gases that make it up. This means that the density of air decreases with increasing altitude.

9. Density Altitude

10. Altimeter
10,000s
1,000s
Kollsman Window
100s
Adjusting Knob

11. Altimeter & Types of Altitude
Indicated Altitude
Altitude indicated on altimeter
Pressure Altitude
Height above standard datum plane
Altitude indicated when set to inches Hg
Density Altitude
Pressure altitude corrected for nonstandard temperature
airplane performance decreases with high density altitude
True Altitude
Actual height above mean sea level (MSL)
Absolute Altitude
Actual height above ground level (AGL)

12. Altimeter Errors
Flying from high pressure to low pressure without changing altimeter setting (instrument thinks you’re higher)
indicated altitude will be higher than actual altitude
one inch change in altimeter setting = 1,000 ft indicated altitude in same direction
Temperature Impact on True Altitude
Warm days
Actual altitude is higher than indicated
Cold days
Actual altitude is lower than indicated

13. Vertical Speed Indicator (VSI)
Rate Information shows stabilized rate of climb or descent
Rate appropriate for student pilots is:
500 feet per minute (FPM) rate of descent or climb
Several second lag

14. Blockages in Pitot-Static System
Blocked Pitot System
Affects Airspeed Indicator (ASI) only
clogged pitot tube with clear drain hole shows zero airspeed
clogged pitot tube with clogged drain hole shows airspeed varying with altitude
Blocked Static System
Affects all pitot-static instruments
ASI = inaccurate airspeed indications
VSI = constant zero indication
ALT= frozen at altitude where blockage
occurred

15. Blockages in Pitot-Static System

16. Vacuum-System
“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”

17. Vacuum System Instruments
-Works by sensing the differences in pressure from vacuum and from outside air.
-Diaphragm

18. Turn Coordinator Miniature Airplane Level Index Turn Index
level flight
Turn Index
standard rate turn (3 deg/sec)
Shows roll and yaw of airplane
Ball shows whether the angle of bank is coordinated with the rate of turn

19. Attitude Indicator (AI)
Artificial Horizon
blue side up
Miniature Airplane
Pointer
Bank Scale
10 bank
20 bank
30 bank
60 bank
Adjustment Knob

20. Attitude Indicator Examples

21. Heading Indicator (Directional Gyro)
Typically “free gyros”
no built-in north-seeking capabilities
Periodically align with compass – error due to gyroscopic precession
Use 360 azimuth
right-most zero omitted
340 is shown as 34
60 is shown as 6
Adjustment Knob

22. Magnetic Compass
Variation - angular difference between Magnetic North and True North. Shown on sectionals and will be taught in navigation lessons
Deviation - compass error due to disturbance from metals and electrical accessories within the airplane. Correction card shows adjustments to magnetic heading
Accurate only when flying in smooth air, in straight & level, unaccelerated flight
When on easterly or westerly heading, use the mnemonic acronym ANDS, “Accelerate North, Decelerate South”
Turning Error
Compass lags when turning from north.
Compass leads when turning from south.
Use acronym, NOSE, “North Opposite, South Exceeds