Height restrictions

[ruddman]

Ok, this is a flight sim question. Kinda. Also just a general interest question as well.

Just to do with height restrictions crossing waypoints etc on descent at some destinations. I know due to traffic on departures for the need for seperation, but some restrictions seem a little crazy(cause I'm not a pilot of a huge jet, what would I know really how it all works?).


Not sure how current this is but say for SIERA arrivals into VHHH. According to a VHHH jeppeson chart I found online and in my flight sim aircaft FMC, you cross MANGO at FL130. But then it's 40/41nm to the next waypoint!

Can't be very efficient on fuel? I've noticed a few other airports with similar kinda height restrictions crossing some waypoints then long legs before descending again. Is it mandatory to always do this?

Does ATC sometimes allow you to ignore this restrictions and plan a full idle thrust descent to approach?


Or is it just bad luck and you cruise along for 40nm to the next waypoint? Do you just hammer the thing to get there sooner or you still gotta obey speed restrictions as well?



Sorry for all the nerdy questions. But some of us pax don't just sit there wondering why we can't use a mobile phone for the whole flight!


Any help appreciated.

[Rainboe]

Places like HKG and SIN can have you descending early on a STAR to make height and speed restrictions. You must follow these requirements unless they are actually removed for you. Many airports have you doing this, but arriving at off-peak times it is likely they will just not give you a STAR. Most major airports do have such restrictions. At HKG, you can follow the very long convoluted arrival, but you are usually aware that short cuts cutting out the extreme routing are the normal order of the day, so you fly your descent planning to do the long routing required, but keeping an eye on fact that you are likely to be cut really short and making sure you are in a position to take advantage of the short cuts that are normall given.

[A Comfy Chair]

As Rainboe as said, basically the requirements are in there for some reason (usually traffic flow... IE holding arrivals above departures in Sydney).

Some are quite restrictive (130 at Mango, the 9000 on the RIVET arrival into Sydney), and are a huge waste of fuel.

Speed restrictions can sometimes be lifted if allowed by sequencing of traffic (ie if there is no-one in front of you you can speed up) ... Except in the US of course, where its 250 below 10,000 no matter what.

Short answer though... you obey the requirements on the chart unless cleared otherwise.

[ruddman]

Thanks for the reply's, guys. Appreciate it.