Altimetry Flashcards
Altimetry based threats
False indication due incorrect pressure reference
False indication due to icing / weather conditions
Risk of impact with terrain or obstacles
Risk of loss of separation with other aircraft
Define height:
Height: The vertical distance of an aircraft, level or point with respect to a specified fixed datum
Define altitude:
Altitude: The vertical distance of an aircraft, level or point, with respect to the datum of mean sea level (MSL)
Define elevation:
Elevation: The vertical distance of a point or a level, on or affixed to the surface of the earth measured from mean sea level
Define Indicated altitude
Indicated Altitude: It is the reading on the altimeter when it is set to the local barometric pressure at mean sea level
Define true altitude
True Altitude: it is the actual vertical distance above mean sea level (MSL)
What type of instrument is an altimeter?
Altimeters (instruments in flight decks showing elevation / altitude), are aneroid barometers
Define SPS
Standard pressure setting
1013.25
Define pressure altitude
Pressure Altitude: is the height above a standard datum plane (SDP), which is a theoretical level where the weight of the atmosphere is 1013.2 hPa (29.92 “Hg ) as measured by a barometer
Define the transition altitude
The Transition Altitude is the altitude at or below which the vertical position of an aircraft is controlled by reference to altitudes (ICAO definition)
When is an aircraft’s position described in altitude (ft)
when an aircraft is at or below the transition altitude, its vertical position is expressed in terms of altitude, which is determined from an altimeter set to sea level pressure (QNH)
VFR flight levels (above 3000ft)
What headings and what levels?
Aircraft track between:
000° - 179° ->
FL ODD number (thousand) + 500
180° - 359° ->
FL EVEN number (thousand) + 500
FL35
FL45
FL55
FL65
IFR Flight Levels
What headings and what levels?
Aircraft track between:
000° - 179° -> FL ODD number (thousand)
180° - 359° -> FL EVEN number (thousand)
Describe the Semi-circular rule
VFR and IFR
FL are offset depending on MAGNETIC headings
East Odd
West Even
When is the vertical position of an aircraft expressed in terms of flight level?
In flight above the transition altitude, the vertical position of an aircraft is expressed in terms of flight levels, which are surfaces of constant atmospheric pressure based on an altimeter setting of 1 013.2 hPa
Define transition level
Transition level is the lowest flight level available for use above the transition altitude (ICAO definition)
Define transition layer
Transition layer is the airspace between the transition altitude and the transition level
What size is transition level?
The transition level is not fixed and is determined by ATS depending on the daily atmospheric pressure
High to low
lookout below
(temperature and pressure)
Flying from a colder area to a warmer area does what to True altitude
Flying from a colder area to a warmer area => True altitude increases for the same indicated Altitude
Flying from a warmer area to a colder area what happens to True altitude?
Flying from a warmer area to a colder area => True altitude decreases for the same indicated Altitude
TEC = ?
TEC = Height/1000 x 4 x ISA deviation.
ISA deviation = ?
ISA Deviation = 15 - (2 x (altitude/1000))
TEC - when ISA deviation is warmer
Add the TEC to the Indicated Altitude to get the True Altitude
Subtract the TEC from the True Altitude to get the Indicated Altitude
TEC - when ISA deviation is cooler
Subtract the TEC from the Indicated Altitude to get the True Altitude
Add the TEC to the True Altitude to get the Indicated Altitude
Temperature error correction from where to where?
Block of air beneath the aircraft
