Airplane Flight Instrument and Navigation Equipment

Question 1

How does the altimeter work?

Answer 1

Altimeter:
- An aneroid barometer that shows the height above a given pressure level, based on standard pressure lapse rate of 1000’ per inch of mercury.
- A stack of sealed aneroid wafers expand and contract with changes in atmospheric pressure received from the static port.
- A mechanical linkage between the aneroid and the display translates the sensed pressure to an altitude indication.

Question 2

How does the VSI work?

Answer 2

VSI:
- Indicates rate-of-climb in fpm (accurate after a 6-9 sec. lag), and rate trend (immediately with rate change).
- A diaphragm inside the instrument is connected directly to the static source.
- The area outside the diaphragm also receives static pressure, but via a calibrated leak (a restricted orifice).
- This configuration essentially responds to static pressure change over time.
- As the diaphragm expands or contracts, a mechanical linkage moves the pointer needle to display the current rate of climb to the pilot.

Question 3

How does the airspeed indicator work?

Answer 3

Airspeed Indicator:
- The airspeed indicator measures the difference between impact (ram) air pressure from the pitot tube and ambient pressure from the static port. The result pressure is called
dynamic pressure and corresponds to airspeed.
▷Dynamic Pressure (airspeed) = Impact Pressure – Static pressure.
- A diaphragm in the instrument receives ram pressure from the pitot tube. The area outside the diaphragm is sealed and connected to the static port. A mechanical linkage converts the expansion and contraction of the diaphragm to airspeed shown on the display dial.

Question 4

What happens if the static port is blocked? The pitot tube?

Answer 4

VSI reads zero, Altimeter is stuck where it was blocked, ASI is higher than when it was blocked, will read it is decreasing. If below it will read you are ascending.

Question 5

Which instruments operate on gyroscopes? Which are electric and which are vacuum powered in your aircraft?

Answer 5

• Artificial Horizon: vacuum powered
• Heading Indicator: vacuum powered
• Turn Coordinator: electric

Question 6

Describe the different instrument scanning techniques.

Answer 6

Inverted V
Racetrack
Wheel and Spoke

Question 7

Describe the instrument scanning errors that you experience in your flying.

Answer 7

Emphasis
Fixation
Omission

Question 8

How does the magnetic compass work?

Answer 8

Magnetic North

Question 9

What are the compass errors?

Answer 9

V: Variation
D: Deviation
M: Magnetic Dip
O: Oscillation
N: Northerly turning errors (UNOS: Undershoot north / Overshoot south)
A: Acceleration errors

Question 10

What is DME?

Answer 10

Distance Measuring Equipment

Question 11

What does VOR stand for?

Answer 11

Very High Frequency
Omni Directional
Range

Question 12

How would you track a VOR?

Answer 12

Identify station
Center needle with To flag
Fly number on the top

Question 13

What’s the difference between a radial and a course?

Answer 13

• Radial away from the station
• Course is to the station

Question 14

What are the VOR service volumes? Where can you find them?

Answer 14

1k-12k / 25nm
1k-18k / 40nm
1k-14.5k/ 40nm | 14.5k-18k/ 100nm | 18k-45k/ 130nm | 45k-60k / 100nm

Question 15

What does ILS stand for?

Answer 15

Instrument Landing System

Question 16

What are the components of an ILS?

Answer 16

Localizer
Glide slope
Marker Beacon

Question 17

What does GPS stand for?

Answer 17

Global Positioning System

Question 18

What are the elements of GPS?

Answer 18

24 satellites at 10,900nm
5 satellites are in view at any time
3 for 2D
4 for 3D

Question 19

What is RAIM and how many satellites do we need?

Answer 19

Receiver Autonomous Integrity Monitoring
5 satellites required
4 satellites with altimeter input

Question 20

What is WAAS? Do you need RAIM to have WAAS?

Answer 20

• Wide Area Augmentation System
• No. You can shoot an approach with WAAS even if you don’t have RAIM

Question 21

What are the required equipment for IFR flight?

Answer 21

G - Generator / alternator.
R - Radios. Two-way radio communication & navigational equipment suitable for the route to be flown.
A - Altimeter (sensitive, adjustable for barometric pressure)
B - Ball (slip-skid indicator).
C - Clock. Shows hours, minutes and seconds with sweep-second pointer or digital representation. Installed as part of aircraft equipment.
A - Attitude indicator.
R - Rate-of-turn indicator.
D - Directional gyro (heading indicator).

Question 22

Can we fly with inoperative equipment?

Answer 22

• As long as it’s not part of VFR, IFR, or any other required equipment list.
• For air operators, they usually have an MEL which allows them to operate the aircraft if certain identified equipment in inop.
  All inop equipment must be disconnected, placarded, or removed. It must also be documented in the logs.