Altimetry Flashcards
What is a Dyne?
A dyne is the force required to produce an acceleration of 1cm/s^2 to a mass of 1 gramme
What is a millibar?
A millibar is 1000 dynes per cm^2
What is the definition of Height?
The vertical distance of a level, point or object considered as a point measured from a specified datum
What is the definition of Altitude?
The vertical distance of a level, point or object considered as a point measured from mean sea level
What is the definition of Elevation?
The vertical distance of a point or level on, or affixed to, the surface of the Earth measured from mean sea level
What is QFE?
The observed atmospheric pressure at aerodrome level
What is QNH?
The atmospheric pressure at mean sea level
For a threshold QFE to be published, how must threshold elevation relate to aerodrome elevation?
The threshold elevation must be 7ft or more below aerodrome elevation
What is Aerodrome Elevation?
The elevation of the highest point on the landing area
What is Regional Pressure Setting?
The lowest forecast QNH within an altimeter setting region
What is the regional pressure setting used for?
Flight below the transition altitude away from the aerodrome. Used by en-route aircraft to ensure terrain separation
When flying towards an area of low pressure, what happens to an aircraft if the pilot fails to update the altimeter setting
Vertical distance above the ground will decrease even if the altimeter shows a constant altitiude
When are regional pressure settings published?
Published at H hour for the period H+1 and H+2
What is a flight level
A surface of constant atmospheric pressure related to a specific pressure datum of 1013.25mbs and separated from other such surfaces by a specific pressure interval
What is the Transition Altitude?
The altitude at, or below which, the vertical position of the aircraft is controlled by reference to altitude
What is the Transition Level?
The Lowest Flight Level available for use above the transition altitude
What is the Transition Layer?
The airspace between the Transition Altitude and the Transition Level (Never greater than 500ft)
Who determines the Transition Altitude?
Within Controlled Airspace
The transition altitude is determined by the controlling authority and is based on the QNH of the major aerodrome within the controlled airspace
Outside Controlled Airspace
The transition altitiude is determined by the aerodrome authority and is based on the aerodrome QNH
What is the QNE?
It is the reading in feet, on an altimeter when the aircraft is at aerodrome or threshold elevation within 1013.25mbs set on the subscale
When is the QNE used?
When the QNH is outside the limits that can be set on the altimeter subscale
