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.
Aircraft at or below the transition level are to be given the aerodrome…
…QNH
When an aircraft is cleared to descend from a Flight Level to an altitude…
When an aircraft is cleared to descend from a Flight Level to an altitude the appropriate QNH shall be included in the same transmission. If Flight Level vacating reports are required, the request should be included with the descent clearance.
The Transition Level must be passed to the pilot in due time prior to…
The Transition Level must be passed to the pilot in due time prior to his aircraft reaching it during descent (SERA.8015(eb)(2)), either by voice communications, ATIS broadcast or data link
After QNH is assumed to have been set by an aircraft all reference to vertical position shall be in terms of…
After QNH is assumed to have been set by an aircraft all reference to vertical position shall be in terms of altitude. Vacating reports, which have not been requested at the time of the descent clearance, may be in terms of altitude, particularly if the aircraft has only one altimeter
Aircraft are to be given the appropriate QNH prior to…
…commencing an approach
Aerodrome and threshold elevations are to be available upon request. Alternatively, when requested by the pilot, or local procedures require…
Aerodrome and threshold elevations are to be available upon request. Alternatively, when requested by the pilot, or local procedures require, the appropriate QFE shall be given
After a missed approach, vertical position is referred to in terms of…
After a missed approach, vertical position is referred to in terms of altitude. It may be necessary, therefore, to include QNH with the subsequent clearance
If an aircraft makes an instrument approach that is to be followed by a visual manoeuvre (circling) to land on another runway, as appropriate…
If an aircraft makes an instrument approach that is to be followed by a visual manoeuvre (circling) to land on another runway, as appropriate, the QFE aerodrome or QFE threshold is to be given
Cruising levels on ATS routes are notified in the UK AIP at ENR 3. Due to variations of atmospheric pressure…
Cruising levels on ATS routes are notified in the UK AIP at ENR 3. Due to variations of atmospheric pressure the lower Flight Levels will not always be available
The lowest cruising level available for assignment shall be determined at the ACC using…
The lowest cruising level available for assignment shall be determined at the ACC using the appropriate Regional Pressure Setting. On an airway this must always be at least 500 feet above the notified base
Unit procedures for the determination and use of the first available Flight Level above the transition altitude shall be described in…
Unit procedures for the determination and use of the first available Flight Level above the transition altitude shall be described in MATS Part 2.
Except when aircraft are leaving controlled airspace by descent, controllers should not normally allocate a level to an aircraft which provides less than…
…500 feet vertical separation above the base of a control area or airway. This will provide some vertical separation from aircraft operating beneath the base of controlled airspace.
Similarly, controllers should exercise caution when operating close to the upper vertical limit of a control zone or area where it is not contiguous with further controlled airspace
