10. Flight Instruments

Question 1

What are the two categories of flight instruments?

Answer 1

Static
Gyroscopic

Question 2

What are the Static Instruments? (3)

Answer 2

• Altimeter
• Vertical Speed Indicator (VSI)
• Air Speed Indicator (ASI)

Question 3

What are the Gyroscopic instruments?

Answer 3

• Artificial Horizon - attitude indicator
• Heading indicator
• Turn Co-ordinator

Question 4

How does a pitot tube sense air?

Answer 4

Statically - Actual air pressure
Dynamically - AC Moving

Question 5

What can prevent erroneous indications on pitot system?

Answer 5

Double or triple redundancy

• In flight heating to prevent icing
• Covers on ground to prevent water ingress and blockages

Question 6

How does an altimeter subscale affect readings?

Answer 6

Setting a higher pressure on the subscale will cause the altimeter to overread

Setting a lower pressure on the subscale will cause the altimeter to underread

Question 7

What is the VSI?

Answer 7

The Vertical Speed Indicator shows the RATE of
climb or descent in feet per minute. If the
needle is on zero, the aircraft is flying level.

Calibrated in 100ft/minute divisions

Question 8

What are the problems with VSI?

Answer 8

There is always a slight lag in the instrument and between six and nine seconds of steady climb, descent or level flight must elapse before an
accurate reading is displayed.

Question 9

What is an ASI?
How does it work?

Answer 9

Airspeed Indicator
As the aircraft begins to move, the on-rushing
air will result in a greater pressure in the pitot
tube (Static + Dynamic) and, by subtracting the
static pressure, the ASI can indicate the speed at
which the aircraft moves through the air.

Question 10

Displayed on a PFD what are the speed indicators?

Answer 10

White = VF - Flap Operating Speed range
Green = VNO - Normal Operating Speeds
Yellow = VO - Max. Manoeuvring Speed
Red = VNE - Never Exceed Speed

Question 11

What should the errors in the ASI not exceed?

Answer 11

3%, or 5kt.

Question 12

What happens of the pitot is blocked?

Answer 12

no dynamic pressure - airspeed will read the same.

Descend - over read
Ascend – under read

Question 13

What is a Magnetic Compass?

Answer 13

First flight instrument
Mandatory in all AC

Question 14

What are the errors in a magnetic compass?

Answer 14

Deviation
Dip
Accelartion Error

Question 15

How to reduce deviation in magnetic compasses?

Answer 15

• Periodic checks
• Checked at 30’ increments on a compass swing.
  Compass correction card

Question 16

How is indicated airspeed read?

Answer 16

IAS depends on the density of the air, which varies with ambient temperature and
pressure; thus, the IAS is only a measure of the speed over the ground in still air