Altimeter

Question 1

The Altimeter

Answer 1

The altimeter measures static pressure and interprets this as altitude.

Measures static pressure
Decrease in pressure = increase in altitude

Increase in pressure = decrease in altitude

Question 2

Parts of an Altimeter

Answer 2

Numbering
Hands
– Hundredths hand
– Thousandths hand
– Tens of thousandths hand

Kollsman window
Crosshatch

Question 3

Kollsman window

Answer 3

• Tells the altimeter where the “zero” setting is.
• The pilot inputs the local pressure setting (altimeter setting) in this window.

Question 4

Altimeter settings

Answer 4

• QNH - Altimeter setting used to measure vertical distance from the mean sea level
• QFE - Altimeter setting used to measure vertical distance from the field
• QNE - Altimeter setting used to measure vertical distance from the standard datum (29.92 in or 1013 hPa)

Question 5

Types of Altitude

Answer 5

• Indicated Altitude - altitude reading directly displayed on an aircraft’s altimeter
• Calibrated Altitude - indicated altitude corrected for instrument and position errors.
• Pressure Altitude - the height of an aircraft above a standard datum plane, which is a theoretical level where atmospheric pressure is 29.92 inches of mercury (or 1013.25 millibars).
• True Altitude - the actual vertical distance of an aircraft above mean sea level (MSL).
• Absolute Altitude - the vertical distance of an aircraft above the actual terrain directly beneath it, measured in feet above ground level (AGL).
• Density Altitude - Altitude corrected for non-standard temperature.

Question 6

ALTIMETRY TERMS

Height

Answer 6

measured from a specified datum (Normally associated with QFE and height above aerodrome level)

Question 7

ALTIMETRY TERMS

Altitude

Answer 7

measured from MSL (Normally associated with QNH)

Question 8

ALTIMETRY TERMS

Flight Levels

Answer 8

related to the standard pressure datum of 29.92 in” Hg

Question 9

ALTIMETRY TERMS

Cruising level

Answer 9

generic term describing vertical position for a significant portion of the flight and can be height , altitude , or flight level depending on the altimeter setting

Question 10

ALTIMETRY TERMS

Transition Altitude

Answer 10

this is the altitude at or below which the vertical position of an aircraft is expressed and controlled in terms of altitude.

Question 11

ALTIMETRY TERMS

Transition layer

Answer 11

–airspace between transition altitude and transition level.

– Climbing–flight level
– Descending in terms of altitude

Question 12

ALTIMETRY TERMS

Transition Level

Answer 12

this is the lowest flight level available for use above the transition altitude

Question 13

Altimetry errors

Answer 13

When flying in areas of different pressures or temperatures without adjusting for the new pressure on the Kollsman window, your true altitude varies from what you are reading!

Question 14

Altimeter errors

Answer 14

 Time Lag
 Instrument Error
 Position Error
 Maneuver-induced Error
 Pitot Static System Blockages & Leak
 Barometric Error

Question 15

How to remember altimetry errors

Answer 15

Remember the mnemonic: -
WHEN FLYING FROM HIGH TO LOW, LOOK OUT BELOW! -

When flying from low to high, touch the sky!

Question 16

Importance to pilots

Answer 16

• The altimeter looks for PRESSURE.
• Always make sure your altimeter is set to the correct setting!
• If no pressure information is available on departure, set altimeter to the field elevation
• If enroute, you may use a pressure setting of a field within 50 nm of your position