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Units 1

20.05.2015

Submission:

Para 4.3.4.4.3 of new Baro-VNAV criteria requires computation of Xz for an airfield elevation higher than 900 m (2 953 ft) or a promulgated VPA above 3.2°, the origin of the Z surface (Xz) using formula: Xz = min [Value tabulated in 4.3.4.4.2, (HL-RDH)/tanVPA – (ATT + 2* TAS*sinVPA / γ *(TAS + Vw))] but it does not clearly specify the applicable units to use the formula. Have any body has idea to use this formula.

Arif Mumtaz - Civil Aviation Authority - Flight Procedure Designer
Pakistan



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Answer or Commentary:

I.W

I think that you can use either SI or Non-SI units in the formula.
However you have to make sure that you do not mix SI and Non-SI units

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Yes, as Ian says you have to be careful to use everything in the same unit and secondly do not try to group the calculations. Solve it from left to right, respecting brackets and of course operator precedence.

Beat Zimmermann - Air Navigation Institute - Switzerland.


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