M1, S1, C7 - Altimeter Setting And Vertical Reference Flashcards
What are the units for the measurement of pressure?
Hectopascals are the notified units for the measurements of pressure for flying within UK airspace. Pilots are normally expected to carry out their own conversion from Hectopascals to inches of mercury if this is necessary and controllers will only provide pressure settings in inches of mercury when specifically requested by an individual aircraft. A conversion table can be found in Appendix A
Describe Flight Levels
Flight Levels are measured with reference to the standard pressure setting of 1013.25 hPa. Consecutive IFR cruising flight levels above the transition altitude are separated by pressure intervals corresponding to 1000 ft in the ISA up to and including FL410 and by pressure intervals corresponding to 2000 ft in the ISA above FL410
A correctly calibrated pressure altimeter when set to:
(1) QNH altimeter setting will indicate altitude; (2) QFE altimeter setting will indicate height above the reference datum. Both of these settings are rounded down to the nearest whole Hectopascal before being passed to the pilot. However, they are given to the nearest tenth of a Hectopascal if requested.
The Regional Pressure Setting is a forecast of…
…the lowest QNH value within an ASR. The values which are made available hourly for the period H+1 to H+2, are given in whole Hectopascals. ATSUs are to have available the Regional Pressure Setting for the ASR in which they are situated and appropriate adjacent regions. These values are to be passed to pilots when requested or at the discretion of the controller. However, a pressure setting shall not be volunteered if a controller is uncertain that it is appropriate to the flight
Airspace below TMAs and CTAs listed in the UK AIP at ENR 1-7-2 does not form part of…
…the ASR Regional Pressure Setting system. Instead, the QNH of an adjacent aerodrome should be used for aircraft at or below the Transition Altitude
Transition altitude is…
…the altitude at or below which the vertical position of an aircraft is controlled by reference to altitude (or height when QFE is used). Wherever possible there is a common transition altitude for aerodromes within a control zone. Unless otherwise notified the transition altitude for civil aerodromes is 3000 feet
Transition level is…
…the lowest Flight Level available for use above the transition altitude and shall be located at least a nominal 1000 ft above the transition altitude to permit the transition altitude and the transition level to be used concurrently in cruising flight, with vertical separation ensured. Except where an alternative means of calculating the transition level is detailed within local instructions, the transition level may be determined from the table in Appendix A as follows: (1) Within controlled airspace by the controlling authority, where it will normally be based on the QNH of the major aerodrome; (2) Outside controlled airspace by the Aerodrome Operator, where it will be based on the aerodrome QNH.
Transition layer is…
…the airspace between the transition altitude and the transition level. Within the UK, the first available flight level above the transition altitude is separated from the transition altitude by a minimum pressure interval corresponding to a nominal 1000 ft.
A pilot normally assesses the vertical position of his aircraft above obstacles by using an accurately set altimeter. It is imperative, therefore, that controllers always…
…issue the correct pressure setting and that they check the read-back from the pilot
When transmitting altimeter pressure settings that are lower than 1000 hPa, controllers are to…
…specify clearly the unit of measurement and pay particular attention to the read-back.
The table below shows the altimeter subscale settings, the terms in which vertical position is reported and the occasions on which they are used to report to ATSUs
When an aircraft has been cleared to climb from an altitude to a Flight Level, vertical position will be reported in terms of…
When an aircraft has been cleared to climb from an altitude to a Flight Level, vertical position will be reported in terms of Flight Level, unless intermediate altitude reports have been specifically requested by ATC. Similarly when a pilot is descending from a Flight Level to an altitude, the pilot will change to the aerodrome QNH unless further Flight Level vacating reports have been requested by ATC, in which case the QNH will be set following the final Flight Level vacating report
Aerodrome elevation is the elevation of…
Aerodrome elevation is the elevation of the highest point on the landing area. It is the elevation upon which the height for visual manoeuvring (circling) is based. In addition a threshold elevation is published for each runway
The pressure settings associated with aerodrome and threshold elevation are expressed as QFE aerodrome and QFE threshold respectively.
QFE threshold for an instrument runway is used when the threshold elevation is…
The pressure settings associated with aerodrome and threshold elevation are expressed as QFE aerodrome and QFE threshold respectively. QFE threshold for an instrument runway is used when the threshold elevation is 7 feet or more below aerodrome elevation
Prior to taking-off, aircraft are to be given the aerodrome…
Prior to taking-off, aircraft are to be given the aerodrome QNH. The transition altitude and level will only be passed if requested by the pilot.
