View Full Version : Any Speeds ?
blueline69
3rd Jan 2007, 03:22
Just a question. On the old STAR plates for JS there used to be a block that asked please do NOT ask if there are "any speeds for ..." Is this still the case as I see the latest one's don't have it any more and it seems to be common practise of late ?
With the arrival sequencing computer gadget, you should be able to fly at own speed unless instructed to do otherwise. You will even hear the phraseology "keep up speed" as the computer has already worked out your position in the final approach sequence from far out. Thats the theory anyway and thats why there are no speed limit points any more. Most "modern" airports have this ATC helping tool.
saywhat
4th Jan 2007, 05:56
With the arrival sequencing computer gadget, you should be able to fly at own speed unless instructed to do otherwise. You will even hear the phraseology "keep up speed" as the computer has already worked out your position in the final approach sequence from far out. Thats the theory anyway and thats why there are no speed limit points any more. Most "modern" airports have this ATC helping tool.
That's not quite true. The new equipment, as far as I know, takes into consideration that you will maintain standard ATC speeds as published on the plate. It is particularly bad airmanship to ask if speeds apply, especially when the frequency is busy. There is an AIC out that refers to this. If it is the middle of the night, and the ATC has not cancled speeds with you as the only a/c in the TMA, then I suppose there is no harm in asking for speeds to be cancled. Use your nogin. If it's busy, just do what your supposed to, and don't get clever.
slapfaan
4th Jan 2007, 07:13
Regarding speed control:
It's NOT a matter of trying to be "clever or not"...
With the high cost of fuel,your ac nav system calculates a TOD point based on ALT and SPEED constraints,so by deleting speed control eg,the TOD point is delayed by a couple of miles...thereby saving fuel and doing a more efficient descend...
That's off course if YOU'RE flying state of the art equipment,and not a steam engine!!!
The sequencing tool takes its info from the radar feed, using the current ground speeds and distance from the final approach fix. Thats why there shouldn't actually be any speed limit points on the arrival plates, because as you start to reduce the speed, the system has to recalculate your position in the sequence. If there is a delay for you, it will tell the ATC to reduce 1 or more aircraft. And if you have to lose more than 4 min, the chances are good that you'll fly a hold or an orbit.
Thats the system I'm familiar with. JNB's might be different though.
saywhat
5th Jan 2007, 07:20
The Maestro sequencing tool used in conjunction with the Eurocat radar system has an aircraft performance database with all the aircraft cruising speeds,descent profiles etc. programmed into it.It also takes into consideration the aircraft speed limit points built into the arrivals into its calculation of the final sequence into Johannesburg.The Maestro system will calculate the optimum sequence into Johannesburg taking the 5nm spacing on final approach,surface wind and upper air winds into account as well.With regard to requesting no speeds..... the maestro will indicate to the airspace planner which aircraft can fly high speeds or which aircraft need to reduce speed to cross the feeder fix at a later time to ensure a reasonable downwind and no delay in the TMA.ATC's prefer pilots not to request no speeds or the departing runway in order to reduce R.T congestion.
BOK2GO
5th Jan 2007, 12:09
Maestro works out estimates based on speed/distance calculations. These are based on STAR speeds and a/c performance. The ACC controller is given a time for an a/c to cross a beacon (eg. HGV) and through track stretching, speed control and often just great skill and cunning achieves this.
STAR speeds is the yard stick used for this speed/distance calculation. It cannot work out an accurate estimate when a/c are told to fly their own speeds as no two pilots would fly the same speed profile.
This tool has shown in other countries that is has reduced the fuel costs of operators because of far less holds being opened during peak traffic. You may have to start your decent a little ealier but your holding will reduce.
This unfortunaley is all null and void when you have thunderstorms in enroute and in the TMA.
Hope that helps.
Goldfish Jack
9th Jan 2007, 08:18
Seems like a good tool to use, but needs to be properly set up - has 14 classes of a/c from the fastest to the slowest (!). As long as it has been prperly programmed and managed it seems to work pretty well. Is in a monitor stage down here at FACT and seems to be pretty accurate - cant wait to do training on it and use it - should save the airlines a lot of fuel and time.
There are varialbes that can be put it, ie spacing on final, runway in use, winds, and if this is correctly loaded should work like a bomb.
Trainging on it in FACT should commence end of March I believe and we will then see how it works...........