Cancel speed
Join Date: Dec 2000
Location: Over There
Posts: 740
Likes: 0
Received 0 Likes
on
0 Posts
If the performance engineers have worked out that 220kts is the maximum speed you can fly without blowing out the turn and getting too close to the rocks, how can ATC take responsibility for the terrain separation? what criteria do they use and how is it different to what the performance guys calculate? Does ATC do any calculations at all? Genuine questions, I dont know what the answer is.
Cancel speed restriction is clearance to cancel ALL speed restrictions issued by ATC which includes any speeds on charts. It does not cancel speed restrictions imposed by your Company SOP's. (250kts to MSA)
Last edited by cpdude; 7th Apr 2013 at 14:09.
Join Date: Apr 2007
Location: HK- A little bit of industrial China in every breath you take.
Posts: 508
Likes: 0
Received 0 Likes
on
0 Posts
Agreed CP Dude, of course it matters not if you accelerate when above radar lower safe or MSA, of course you cant hit anything if you blow out the turn. Agree entirely, but my question was what calcs do ATC do to clear the requirement? What do the departure controllers implement to clear us when there is an obstacle defined restriction? Is it simply a matter of observing our current ROC?
Join Date: Dec 2000
Location: Over There
Posts: 740
Likes: 0
Received 0 Likes
on
0 Posts
Lowkoon,
Departures paths use criteria based on minimum values to determine terrain clearance. These are based on the minimum rate of climb required as is stated as "standard" with either PANOPS or TERPS etc. My memory fails me but I believe it's about 200'/nm on departure. Any departure which requires a higher ROC will have the minimum ROC required posted on the departure sheet.
Based on the minimum ROC the turn at PORPA allows for only a turn radius associated with a speed of 220kts. Not being an ATC type, I'm not sure what formulas are programmed into their computers but I'm sure they can automatically calculate your current altitude, ROC and speed and make the calculation seamlessly and automatically for the controller to then clear you unrestricted or high speed.
White None,
You are correct once cleared for high speed.
Departures paths use criteria based on minimum values to determine terrain clearance. These are based on the minimum rate of climb required as is stated as "standard" with either PANOPS or TERPS etc. My memory fails me but I believe it's about 200'/nm on departure. Any departure which requires a higher ROC will have the minimum ROC required posted on the departure sheet.
Based on the minimum ROC the turn at PORPA allows for only a turn radius associated with a speed of 220kts. Not being an ATC type, I'm not sure what formulas are programmed into their computers but I'm sure they can automatically calculate your current altitude, ROC and speed and make the calculation seamlessly and automatically for the controller to then clear you unrestricted or high speed.
White None,
You are correct once cleared for high speed.
Last edited by cpdude; 17th Apr 2013 at 12:53.
Join Date: Dec 2012
Location: Here
Posts: 464
Likes: 0
Received 0 Likes
on
0 Posts
Who knows if they even need a formula....? When you're cleared for high speed before Porpa, you're normally ALREADY above the highest piece of rock on your departure track before they give it.
Join Date: Oct 2009
Location: Hong Kong
Posts: 601
Likes: 0
Received 0 Likes
on
0 Posts
however, don't forget that in a big grown up aeroplane you can goto Vref +100 below MSA which could be 280kts+
STP
Join Date: Jan 2012
Location: Not in a Bus
Posts: 325
Likes: 0
Received 0 Likes
on
0 Posts
STP
Sorry, according to the rules
doesn't qualify. It HAS to be 280+. Love to help but..... Cannot, (Not that I'm displaying the raging inferiority complex all Jumbo drivers will vehemently deny now that the BigBus is around). 
Sorry, according to the rules
towards 280kts
Last edited by White None; 19th Apr 2013 at 09:32.
Join Date: Jan 2012
Location: Not in a Bus
Posts: 325
Likes: 0
Received 0 Likes
on
0 Posts
I Love Rubber Dog****. It doesn't get lost/pissed in the terminal, it doesn't pinch my bum. It doesn't bleat if we're late or require apologies for stuff out of my control. It doesn't say "Cannot". It doesn't expect me to buy it, and it's mate's dinner and it always respects me in the morning.
Join Date: Jan 2012
Location: Not in a Bus
Posts: 325
Likes: 0
Received 0 Likes
on
0 Posts
Trevor the Moose
Amazing that so many in the company STILL!! don't know that most of us fly both, on the same pay. Having the seniority to do so I now get to pick either and where poss, fly freight. Why?.... See above.
Amazing that so many in the company STILL!! don't know that most of us fly both, on the same pay. Having the seniority to do so I now get to pick either and where poss, fly freight. Why?.... See above.
Last edited by White None; 22nd Apr 2013 at 05:39.
Ok,
Now that this thread has gone "Off Topic" with the usual "im better than you" BS.
I have another ATC question.
The requirements at FL130 inbound to HKG, if ATC clear you below can we disregard the restriction?
If not, often they descend us to an altitude, do we have to maintain STD until passing the waypoint, ie pass at FL130 ISO 13000 on QNH (on our charts the restriction is FL130)
I would be interested in hearing from the ATCer's on this one.
JY
Now that this thread has gone "Off Topic" with the usual "im better than you" BS.
I have another ATC question.
The requirements at FL130 inbound to HKG, if ATC clear you below can we disregard the restriction?
If not, often they descend us to an altitude, do we have to maintain STD until passing the waypoint, ie pass at FL130 ISO 13000 on QNH (on our charts the restriction is FL130)
I would be interested in hearing from the ATCer's on this one.
JY