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Setting QNH on descent

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Setting QNH on descent

Old 4th Apr 2017, 09:47
  #21 (permalink)  
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Capn Bloggs

Could you paste in ENR 1.7 section 2.1.4.?

Thanks
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Old 4th Apr 2017, 09:52
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This is not an issue of SOP but AIP. If it doesn't say so it shouldn't be done. In India it is not done. In Europe yes.
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Old 4th Apr 2017, 09:56
  #23 (permalink)  
 
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Originally Posted by valhalla634 View Post
Capn Bloggs

Could you paste in ENR 1.7 section 2.1.4.?

Thanks
From the NZ AIP:

2.2.2 The pilot of an aircraft must:
(a) when climbing above 13,000 ft, set the altimeter to 1013.2 hPa;
and
(b) when descending through FL150, set the altimeter to the
appropriate zone area or aerodrome QNH.
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Old 4th Apr 2017, 10:10
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To the OP, I withdraw my previous comment about the transition level not changing in Aus. It does with QNH, my bad, you're correct. Been a while since I studied the Aus regs.
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Old 4th Apr 2017, 10:35
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It needs to be kept in mind that a lot of European T/Ls are very low - 5000ft or so. Hence set QNH as soon as cleared to an altitude, you just run out of time otherwise.
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Old 4th Apr 2017, 10:43
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Originally Posted by AU AIP ENR 1.7 section 2.1.4
2.1.4 The position to change between QNH and 1013.2HPA shall always be in the Standard Pressure Region on climb after passing 10,000FT and prior to levelling off, or on descent to a level in the Altimeter Setting Region prior to entering the Transition Layer and is shown in Figure 1.
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Old 4th Apr 2017, 10:48
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True mustafagander. Even less, and they do change for QNH less than 1013, and cold temperatures. Some modern ATIS are just METAR announciators and do not have TL info on them. Other places are 7000ish. Elsewhere you could be crusing at FL70 and enter TMA from a side and set QNH for this, as in the TMA TL is FL120. Weird stuff.

Hence the other approach to switch ASAP works the best. To support the risk assesment case, descent to altitude from above, let's say, FL180 is seldom the clearance. Typically last assigned FL is around 120 (whether or not you get to maintain it), mostly because of ATC sector fragmentation which is due to national borders and capacity demands.
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Old 4th Apr 2017, 10:55
  #28 (permalink)  
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The above diagram states that PRIOR to Transition "Layer" set QNH. It does not state AT.
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Old 4th Apr 2017, 18:10
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Good airmanship:

Set QNH on SBY Altimeter when received in cruise prior to descent.
When first cleared to an altitude set QNH on main altimeters and crosscheck the value set to be near enough the one set on Stnadby Alreceived during flight to avoid a blunder error.
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Old 5th Apr 2017, 11:18
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Originally Posted by valhalla634 View Post
The above diagram states that PRIOR to Transition "Layer" set QNH. It does not state AT.
Correct. BleedingAir's comments are not in accordance with the Australian rules.
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