Pitot Static

Question 1

Pitot static instruments

Answer 1

Airspeed Indicator
Altimeter
Vertical Speed Indicator

Question 2

Altimeter

Answer 2

• Simply a barometer that measures static pressure of the air around the aircraft.
• Uses only the static pressure

Question 3

Altimeter operation

Answer 3

• Aneroid wafer
• Stack of hollow, elastic metal wafers
• Expand and contract as pressure changes

Question 4

Pressure window

Answer 4

Kollsman window
•Small adjustable subscale that allows the current altimeter setting to be set in
•Important to reset with current altimeter reading
•Above 18,000’ always set at 29.92

Question 5

Pressure error

Answer 5

• Caused by not setting the current altimeter setting

* High to Low-Look out below, low to high plenty of sky

Question 6

Altimeter density error

Answer 6

• Caused by change in temperatures, not all altimeters account for a change it temperature
• Temperature lapse rate slower in hot air, faster in cold air (standard lapse rate -2 degrees per 1,000 ft)
• Hot to cold = low, cold to hot = high

Question 7

Airspeed indicator

Answer 7

• Displays the speed of the aircraft through the air
• Only instrument that uses both types of pressure
• Measures the difference between the two pressures

Question 8

Airspeed indicator operation

Answer 8

• Instrument is contained within a sealed case
• Inside of the case is vented to the static port
• Pressure sensitive diaphragm
• Ram pressure line is connected directly to one side of the diaphragm
• Diaphragm expands and contracts in proportion to the difference between the two pressures

Question 9

Position error

Answer 9

Occurs when the static port senses an erroneous static pressure
•Mainly caused by slipstream

Question 10

Airspeed density error

Answer 10

Occurs when there is a change in the altitude or temperature that the instrument does not take into account.

Question 11

Compressibility error

Answer 11

Caused by high speed packing of air into the pitot tube.

Question 12

Vertical speed indicator

Answer 12

• Provides reference to rate of change
• Shows both rate and trend
• Uses only static pressure

Question 13

VSI Operations

Answer 13

• Expandable Capsule (Diaphragm)
• Directly connected to static port
• Connected through mechanical linkage
• Calibrated Leak: Instrument Case’s connection to the static port- Allows capsule to change pressure more gradually
• Pressure inside of diapragm changes the same as the outside air
• Pressure in instrument case changes slower because of calibrated leak.

Question 14

Blocked pitot

Answer 14

Airspeed- 0
Altimeter- works
VSI- works

Question 15

Blocked pitot and drain hole, static open

Answer 15

Airspeed- high during climb, low during descent
Altimeter- works
VSI- works

Question 16

Blocked static, open pitot

Answer 16

Airspeed- low on climb, high on descent
Altimeter- frozen
VSI- frozen

Question 17

Using alternate static source

Answer 17

Airspeed- reads high
Altimeter- reads high
VSI- momentarily shows climb

Question 18

Broken VSI glass

Answer 18

Airspeed- reads high
Altimeter- reads high
VSI- reverses

Question 19

Static check

Answer 19

Every 24 months

Question 20

Reset altimeter?

Answer 20

Every 100 nm