Flying in China airspace, decomp procedures
 

Hi,

I am keen to hear what is your view on this. Usually ATC will give an offset in Chinese airspace and the decompression procedures call for right turn 30 deg and offset 5nm. Given that you are already offset, if you were to encounter rapid decompression, will you:

1) offset additional 5nm or
2) offset the remaining "nm'. (For eg. ATC gives an instruction to offset 3nm to the right, and when encountering rapid decompression, you will offset additional 2nm) or
3) not offset (due to ATC's superior tracking capabilities)

Looking forward to hear your thoughts

Offset additional 5 nm

I think I would ask ATC (or even tell them what I’m going to do) after the descent has been set up. Having experienced offsets of 20nm and greater in the PRC, you could easily fly into a military area, into another airway or, even worse, compromise your terrain clearance being so far off flight plan. Several of the Chinese routes we fly on have oxygen critical points and seriously high ground, with escape procedures not compatible with a 5nm offset, or a 30deg turn for that matter...

Who gives a damn about flying into mil zone during such critical event? Also squawk 7700 is part ouf emergency descent procedure anyway and grid MORA/MSA should be known at any given moment. If anyone will ask any questions after that is the least of your concert at that moment.

FullWings is correct. If you operate over extremely high terrain such as found in northern China and Mongolia your company must have designated oxygen critical points and escape routes to follow. Offsetting or departing from these is extremely dangerous, especially with MORA/MSA's in those areas as high as 20,000ft plus.

The question is perfectly valid, there is a lot of airspace over mainland P.R.C. where MORA/MOCAs are below 14k. In that respect, FullWings is also correct saying ATC liaison is a priority, similar to the original option c).

Thank you. I would also have a good look around on TCAS as it’s not guaranteed to deconflict if you are changing altitude at >7,000fpm, which can be achieved in a rapid descent in certain conditions.