Section 3 - Altimetry Flashcards
What is the difference between altitude, height and FL?
Altitude - Vertical distance of a point or object considered as a point, from mean sea level
Height - Vertical distance of a level, point or object considered as a point above a specific datum
FL - surface of constant pressure based on related to pressure datum 1013.2 separated by pressure intervals
What is the difference between elevation and aerodrome elevation?
Elevation is the vertical distance of a point or level on or affixed to the surface of the earth - from mean sea level
Aerodrome elevation is the elevation of the highest point on the landing area.
Describe QFE and how is it used?
Corrected barometric pressure for a specified datum used by Brit Mil A/C when landing, taking off and circuit flying.
Airfields without a designated runway, QFE datum is airfield elevation
Other airfields it is the touchdown zone of runway in use.
More than one runway it is the instrument runway.
Mixed QFE’s are not allowed.
What is Touchdown Zone?
Touch down zone elevation?
Portion of a runway where aircraft first contact.
Highest runway centreline in the Touch Down Zone.
What is SAS and explain its use?
SAS assumes mean sea level pressure of 1013.2
used for all flying above the TA and when above 3000amsl in the UK except:
Under instructions from ATC, HMS or ASACs
High energy manoeuvres requiring rapid changes of altitude or heading.
What is Aerodrome QNH and when is it used?
observed pressure at an aerodrome corrected for temperature and reduced to mean sea level with ICAO formula. Message is to include airfield elevation.
Calculating TA
Calculating MSFL
flight in vicinity of some civil aerodromes
landing datum for some foreign and civil A/C
On request by military pilots
What is RPS and state its use?
Lowest forecast QNH within designated ASR
Used for flying at or below TA away from circuit
Available for H0-H+1 for local and adjoining ASRs
Available for H+1-H+2 from the Met Office
used to calculate MSFL for en-route flying
When would you use Force QNH?
When controlling air systems within a defined Op/Ex, controllers should use Force QNH.
