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Metric cruising level rounding error


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PFPX Version 1.12

OS: Windows 7 64-bit

Severity: Medium

When planning a flight from VHHH/HKG to PANC/ANC that traverses Chinese Metric RVSM airspace, PFPX planned at Standard Level 9500m and Standard Level 9800m.

According to the Chinese CAA (http://www.chinarma.cn/English/flightlevelallocationscheme.html) these are equivalent to FL311 and FL321, respectively.

However, in the Flight Level Profile field and Navigation Log, these are listed as FL312 and FL322. Using a conversion factor of 3.28 ft per m, these levels are in fact correct to the nearest 100 feet. However, the requirement of the airspace is to operate using the table from the Chinese CAA.

Steps to reproduce: Plan a flight at Standard Level 9500m or Standard Level 9800m (this bug probably also occurs for other levels too).

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My understanding is that the navdata stores a "cruise table" code rather than the actual accepted levels. Is that incorrect?

A separate, but possibly related issue is that when submitting to VATSIM, the cruising level field is filled in with the exact altitude (e.g. 9500m -> 31168ft). I would suggest that it would make more sense for this be rounded.

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Navigraph 1313. I'll retry this when I stop being lazy and get 1401 (although their new manager program looks interesting). I'll also see if I know anyone with an Aerosoft database who might be able to try this.

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Hi David,

Just planned a flight from VHHH to PANC off the bat as I use Aerosoft Data 1401.

Navlog's giving me an initial of FL351 and on the ATC plan it says K0910S1070

Is that what your after?

It changes to FL350 once required.

Cheers,

Tim

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10700m * 3.28 = 35096ft ~ 35100ft, which gives the correct answer regardless of whether rounding is used or a lookup table.

For sure, 9500m converted to feet and rounded using normal rules gives 31200ft. However, according to the Chinese CAA, aircraft using altimeters that read in feet should operate at 31100ft.

I have now tried with Navigraph 1401 - same thing happens.

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10700m * 3.28 = 35096ft ~ 35100ft, which gives the correct answer regardless of whether rounding is used or a lookup table.

For sure, 9500m converted to feet and rounded using normal rules gives 31200ft. However, according to the Chinese CAA, aircraft using altimeters that read in feet should operate at 31100ft.

I have now tried with Navigraph 1401 - same thing happens.

David,

Just done this now and for me it's the same. It says 9500 in the ATC Plan and Nav Log it says FL312. Perhaps not just isolated too navigraph?

Cheers,

Tim

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What I suspect is that the navdata stores a "cruise table" code (see the "Details" tab of the route editor, last column) and PFPX stores the definition of these "cruise tables" in it's internal data files.

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