Teorija kontrole zračnog prometa I –
nastavna cjelina 71
Level in aviation
Altimeter setting procedures
Biljana Juričić, DSc
Fakultet prometnih znanosti
Zavod za aeronautiku
Katedra za kontrolu leta
TEORIJA KONTROLE ZRAČNOG
PROMETA I
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5.ODREĐIVANJE I DODJELA VISINE (ALTIMETRY AND LEVEL ALLOCATION)
• 5.1.Određivanje visine(Altimetry)Razumjeti odnos između visine, visine leta i razine leta; QFE, QNH, standardni pritisak.(Appreciate the relationship between height, altitude and flight level; QFE, QNH, standard pressure)
• I5.2.Prijelazna razina(Transition Level)Razumjeti odnos između prijelazne razine, prijelazne visine leta i prijelaznog sloja; ICAO Doc 4444, ICAO Doc 8168.(Appreciate the relationship between transition level, transition altitude and transition layer; ICAO Doc 4444, ICAO Doc 8168). Izračun prijelazne razine leta (Calculate transition levels)
• I5.3.Dodjela razine(Level Allocation)Opisati sustav dodjele razine krstarenja; Annex 2, tablice putnih razina.(Describe the cruising level allocation system; ICAO Annex 2, tables of cruising levels). Odabir prikladne visine; razine leta, visine u odnosu na srednju razinu mora, visine u odnosu na referentnu točku.(Choose appropriate levels; Flight levels, altitudes, heights)3Teorija kontrole zračnog prometa I
Ciljevi osposobljavanja –
- Learning Objectives:
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Level in aviation
Level in aviation – generic term meaning variously:
• Altitude
• Flight Level
• Height
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Altitude
• The vertical distance of a level, at which point or
an object considered as a point, is measured
from mean sea level (MSL) taking into
consideration QNH pressure.
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Height
• The vertical distance of a level, at which a point
or an object is considered as a point, measured
from a specified datum taking into consideration
QFE pressure
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Flight level
• A surface of constant atmospheric pressure
which is related to a specific pressure datum of
1 013.2 hPa (standard pressure - QNE) and is
separated from other such surfaces by specific
pressure intervals (18 hPa=500 ft).
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Elevation
• The vertical distance of a point or an object at
surface measured from mean sea level (MSL)
taking into consideration QNH pressure.
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QNH
• altimeter subscale setting of pressure value at the
aerodrome elevation which is calculated using pressure
reduction to MSL
• The altimeter sub-scale setting to obtain elevation when
on the ground.
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QNE
• altimeter subscale setting of pressure value of ISA
standard atmosphere 1013,25 hPa
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QFE
• altimeter subscale setting of pressure value
measured at the aerodrome elevation
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USS
QNE
QFE
Height
Altitude
Flightlevel (FL)
QNE<QNH
QNE>QNH
QNE=QNH
QNE
Elevation
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Characteristic of atmosphere
hp
1∝ 1 hPa ≈ 30 ft
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Atmospheric rule...
• The higher the level, the lower the pressure
• The lower the level, the higher the pressure
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Altimeter
• equipment that measures pressure difference
between pressure reference datum and actually
mesured pressure value and calculates
corresponding vertical distance
• reference data: QNH, QNE, QFE
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• setting the right pressure datum is essential for calculating the real vertical position of the aircraft
• if not, altimeter indicates correct value but real altitude of the aircraft is different (aircraft is higher or lower then it should be)
• the pressure datum in such cases is higher or lower in accordance with MSL
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Example 1.
• QNH is 1000 hPa
• aircraft 1 is at altitude 7500 ft
• aircraft 2 is entering the same airspace at altitude
8500 ft but with incorrect pressure of 1036 hPa
What is the real vertical distance between aircraft??
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8500 ft
7500 ft
USS
QNH=1000 hPa
MSL
QNH=1036 hPa
36*30=1080 ft
1080 ft !!1
2
Incorrect reference datum!
Altitude7420 ft
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Example 2
• upper limit of the defined airspace is 9000 ft MSL
• QNH is 1036 hPa
• aircraft 1 is at altitude 7500 ft
• aircraft 2 is entering the same airspace at altitude
8500 ft but with incorrect pressure of 1000 hPa
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7500 ft
8500 ft
9000 ft
9580 ft
USS
QNH=1036 hPa
MSL
QNH=1000 hPa
36*30=1080 ft
8500 ft !!
1
2
Incorrect reference datum!
Altitude
36*30=1080 ft
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• same problems can appear with obstacle
clearance
• if IFR aircraft is on the flight level which coinside
with minimum obstacle clearance altitude and
QNH is less then QNE, then minimum obstacle
clearance is less then it should be CFIT – Controlled Flight Into
Terrain
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FL
USS
MSLIncorrect reference datum!
Altitude
if QNH<<<<QNE
MOCA
y<<<<x
IFR flight
x
FL 0
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if QNH<<<<QNE VFR flight
USS
MSL∆∆∆∆pIncorrect reference datumof QNE!
Altitude
MOCA
xy
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• two aircraft are on head-on directions but with differently set pressure (aircraft 2 has wrong setting)
• What is the real vertical distance between
aircraft??
Example 3
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USS
QNH=990 hPa
MSL20*30=600 ft
1
2
Incorrect reference datum!
Altitude
QNH=1010 hPa1000 ft
Real vertical distance between aircraft is 400 ft!
600 ft
400 ft
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Example 4
• aircraft 1 is on the runway with altimeter set to
the QNH and shows 510 ft
• aircraft 2 is in the vicinity of aerodrome with
altimeter set to the QFE=990hPa an shows 650 ft
• altitude of aircraft 2?
• QNH?
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USS
MSL
650 ft, QFE=990 hPa
510 ft, QNH
510 ft, QNH
Altitude
Height
QNH=1007 hPa!
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• aircraft 1 is at height 3500 ft with altimeter set to QFE = 980 hPa
• elevation of aerodrome is 150 m
• What is the altitude of aircraft 1 and QNH?
• aircraft 2 enters same airspace with altitude of 4500 ft, but with wrongly set QNH of 1010 hPa
• What is the real vertical separation between aircraft?
Example 5
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3500
4500
USS
MSL
3500 ft, QFE=980 hPa
510 ft, QNH=?
150 m
Altitude
Height
ft
4500 ft, QNH=1010 hPa
x=?
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RWY
TA
TL
TLY
QNH
QNE
QNE
QNE
QNE
QNH
QNH
QNH
MSL
Altimeter setting procedures
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Altimeter setting
When approaching and departing from aerodrome pilot shall set altimeter according to following levels:
Transition Altitude (TA)
Transition Level (TL)
Transition Layer (TLY)
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Transition Altitude (TA)
• highest possible altitude at which aircraft can
operate with alimeter set to QNH
• designated by the State and published in AIP
• it can be different for every aerodrome or unique
for whole airspace
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Transition Level (TL)
• lowest possible flight level at which aircraft
can operate with alitimeter set to QNE
• depends on QNH
• ATC gives information about TL when aircraft
is in approach
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Transition Layer (TLY)
• area between transition level and transition
altitude
• depends on QNH
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Calculation of transition levels
• 3 different cases:
QNH < QNE
QNH = QNE
QNH > QNE
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if QNH < QNE
QNE
QNH
QNH<QNE ⇒ ∆∆∆∆ P
∆ h = ∆ P*30 ft
0
FL
alt.
∆ h = ∆ P*30 ft
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if QNH = QNE
QNE
QNH
QNH=QNE ⇒ ∆∆∆∆ P=0
0
TL
TA
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if QNH > QNE
QNH
QNE
QNH>QNE ⇒ ∆∆∆∆ P
∆ h = ∆ P*28 ft
0
alt.
TA
∆ h = ∆ P*28 ft
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Example 1 TA=4000 ftQNH<QNE ⇒ ∆ PQNH=1000 hPa∆ P= 13 hPa ⇒13*30=390 ft
QNH
∆∆∆∆ h =390 ft
0 QNE
10
20
30
40
50
1000
2000
3000
4000
5000
∆∆∆∆ h =390 ft
TL=FL45
TLY=110 FT45
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Example 2 TA=4000 ftQNH=QNE ⇒ ∆ PQNH=1013 hPa∆ P= 0 hPa
QNH
∆∆∆∆ h = 0 ft
0
QNE
10
20
30
40
50
1000
2000
3000
4000
5000
∆∆∆∆ h =0 ft
TL=FL40
TLY= 0 FT
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USS
MSL∆∆∆∆p=QNH1-QNH2Indicated altitude 1- but Incorrect reference datum of QNH1!
Altitude1
xy
QNH1
QNH1
QNH2
Actual altitude AMSL(altitude1- ∆∆∆∆p*30)
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• if aircraft set altimeter at departure aerodrome at QNH1 and is flying en-route at altitude 7000 ft with the same pressure towords the high terrain, aircraft will be at lower level above terrain with possible obstacle clearance infringed
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• to avoid such errors it is necessary to update QNH (QNH2 at previous picture) using values supplied by an aerodrome with ATC nearest to the route of flight
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Transition Altitude
• A transition altitude shall normally be specified
for each aerodrome by the State in which the
aerodrome is located
• Where two or more closely spaced aerodromes
are located so that coordinated procedures are
required, a common transition altitude shall be
established. This common transition altitude shall
be the highest that would be required if the
aerodromes were considered separately
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• As far as possible, a common transition altitude should be established for
– groups of aerodromes of a State or all aerodromes of that State
– aerodromes of adjacent States (on the basis of an agreement)
– States of the same flight information region (on the basis of an agreement)
– States of two or more adjacent flight information regions or one ICAO region (on the basis of an agreement)
– for aerodromes of two or more ICAO regions when agreement can be obtained between these regions
Transition Altitude
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Transition Altitude
• The height above the aerodrome of the transition
altitude shall be as low as possible but normally
not less than 900 m (3 000 ft)
• Transition altitude may be established for a
specified area on the basis of regional air
navigation agreements
• Transition altitudes shall be published in
aeronautical information publications and shown
on the appropriate charts
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Transition
• in TMA, in approach procedures aircraft fly at flight levels
with altimeter set to QNE till reaching transition level.
Then pilot change altimeter setting to QNH and vertical
position of aircraft is exspressed as altitude
• when departing, aircraft receive QNH information and
set altimeter to QNH. Its level is express as altitude untill
aircraft reach transition altitude when pilot set altimeter
to QNE and vertical position of aircraft is expressed as
flight level
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• ATC may clear aircraft (turbo-prop) to operate
using QNH above transition level if so required
for the purpose of the uninterrupted descent
• ATC gives altitude to descent to and QNH
Transition-exception
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• if TA is defined for every aerodrome then aircraft
outside TMA fly according to semicircular system
of cruising levels
• ICAO Annex 6, Doc 8168:
– when no transition altitude is established for the
area, aircraft in the en-route phase shall fly at
flight levels
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Terrain clearance
• QNH altimeter setting reports should be provided from sufficient
locations to permit determination of terrain clearance with an
acceptable degree of accuracy
• For areas where adequate QNH altimeter setting reports cannot be
provided, the appropriate authorities shall provide the information
required to determine the lowest flight level which will ensure
adequate terrain clearance. This information shall be made
available in the most usable form.
• Appropriate services shall at all times have available the
information required to determine the lowest Flight level which will
ensure adequate terrain clearance for specific routes or segments
of routes. This information shall be made available for flight
planning purposes and for transmission to aircraft in flight, on
request.
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• ATC is responsible for terrain clearance of aircraft only if
aircraft is under radar vectoring procedures and ATC
takes into consideration MRVA
• MRVA – Minimum Radar Vectoring Altitude
• MRVA - the lowest altitude which may be used for radar
vectors for IFR flights taking into account the minimum safe
height (of 1000 ft above the highest obstacle within a radius
of 8 km) and airspace structure (lower limit of the controlled
airspace plus a buffer of 500 ft). The MRVA is rounded to the
nearest 100-ft interval.
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Transition layer
• in some States, the minimum depth of transition
layer may be established
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• aircraft shall fly corresponding to the magnetic track in the table of cruising levels in Annex 2
• Flight level zero shall be located at the atmospheric pressure level of 1 013.2 hPa. Consecutive flight levels shall be separated by a pressure interval corresponding to at least 500 ft (152.4 m) in the standard atmosphere.
Semi-circular table of cruising levels
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ODD
000
179°180°
359°
EVEN
Semi-circular table of cruising levels
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• VFR flight level is IFR flight level + 500 ft
(IFR FL 70, VFR FL 75)
• if TA is established for whole FIR then VFR flights
above TA will fly using flight levels and at or
below will fly at altitudes (in Croatia)...
• pilot of VFR flight selects flight level
Semi-circular table of cruising levels
for VFR flights
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• ATC allocates flight level or altitude for IFR flights
in controlled airspace
Semi-circular table of cruising levels
for IFR flights
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Non-RVSM Airspace
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RVSM airspace
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ODD EVENIFR VFR IFR VFR1000 20003000 3500 4000 45005000 5500 6000 65007000 7500 8000 85009000 9500 TA 100 105110 115 120 125... ... ... ...270 275 280 285290 - 310 -
Semi-circular table of cruising levels
for FIR Zagreb
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Calculations of TL, TLY
1. QNH=990 hPA, TA=5000 ft. Calculate TL, TLY.
2. QNH=1043 hPa, TA=8000 ft. Calculate TL, TLY.
3. QNH=980 hPa, TA=7500 ft, TLY=min 500 ft. Calculate TL.
4. QNH=960 hPa, TA=6000 ft, TLY=min 1000 ft. Calculate TL.
5. QNH=1020 hPa, TA=8500 ft, TLY=min 500 ft. Calculate TL.
6. QNH=1038 hPa, TA=4000 ft, TLY=min 1000 ft. Calculate TL.
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Example 1– flight level
USS
MSL
QNH=1020 hPa QNH=1025 hPa QNH=1020 hPa QNH=1030 hPa
TA=6000 ft
QNE=1013 hPa
∆∆∆∆p=QNH-1013
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USS
MSL
QNH=1010 hPa QNH=1015 hPa QNH=1020 hPa QNH=1030 hPa
TA=6000 ft
Example 2– flight level
∆∆∆∆p=1013-QNH
QNE=1013 hPa
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Calculations of TL, TLY1. QNH=995 hPA, TA=5000 ft. Calculate TL, TLY.
2. QNH=1040 hPa, TA=6500 ft. Calculate TL, TLY.
3. QNH=970 hPa, TA=7500 ft, TLY=min 500 ft. Calculate TL.
4. QNH=1015 hPa, TA=8500 ft, TLY=min 500 ft. Calculate TL.
5. QNH=1036 hPa, TA=4500 ft, TLY=min 1000 ft. Calculate TL.6. TA=5000 ft, QNH=970 hPa. A/c is at FL050. Where is FL 0? What is the altitude of the a/c?
7. TA=6500 ft, A/c is constantly at FL080. In QNH=1040 hPa. Where is FL 0? What is the altitude of the a/c?
8. In Area 1 QNH =991 QNH, in Area 2 QNH=999 hPa and in Area 3=1022 hPa. Draw path of the a/c. A/c is at FL100.
9. A/c is approaching aerodrome with height=650 ft. QNH=1015 hPa. Another a/c is at the same level but with altimeter set to QNH. Its altimeter shows 3500 ft. Calculate QFE and aerodrome’s elevation in meters.
10. Third aircraft is entering the same airspace with FL050. What is the vertical separation between these aircraft?
11. Aircraft is at 6000 ft, QNH=980 hPa and its MSH is 2000 ft above the highest obstacle in the radius of 8 km. Another aircratf is entering the same airspace with the wrong altimeter setting QNH=1028. What is the vertical terrain separation of the second aircraft?
12. Elevation of the terrain is 2000 m. What must be the lowest altitude or FL at which aircraft will have MSH=2000 ft. TA=9000 ft.
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1. TA=4000 ft, QNH=970 hPa. A/c is at FL040. Where is FL 0?
What is the altitude of the a/c?
2. TA=4500 ft, A/c is constantly at FL070. In QNH=1035
hPa. Where is FL 0? What is the altitude of the a/c?
3. In Area 1 QNH =980 QNH, in Area 2 QNH=1000 hPa
and in Area 3=1030 hPa. Draw a path of the a/c.
A/c is at FL120. Draw FL0.
Procedures Applicable to
Operators and Pilots
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Flight Planning
• the 3 requirements altitudes or flight levels
selected by the Operator should:
– ensure adequate terrain clearance at all points
along the route to be flown
– satisfy ATC requirements
– be compatible with the cruising levels appropriate
to the magnetic tracks
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Pre-flight Operational Test
• QNH – AD elevation + the height of the altimeter within the tolerance ± 60 ft for altimeters with the test range of 0 to 30000 ft and ± 80 ft for altimeters with the test range of 0 to 50000 ft
• QFE - the height of the altimeter within the tolerance ± 60 ft for altimeters with the test range of 0 to 30000 ft and ± 80 ft for altimeters with the test range of 0 to 50000 ft
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Thank you!! ☺
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