Ground Speeds

[Oz Control]

While on a famil visit to Perth the other day I noticed the flow controller favoured issuing ground speeds to inbound aircraft to achieve the desired spacing. How difficult is it to maintain a given ground speed while in the cruise? Are other methods (IAS or mach number) preferable? :hmm:

[Sheep Guts]

Yes this can be hard but Mach number is used where I am alot and an indicated airspeed, when on descent. Maintaining a ground speed on descent is a bit hard especially if the winds change, I find.


Sheep

[Capt Claret]

Maintining a ground speed is as simple as adjusting power to achieve the appropriate readout on the GPS/LNAV.

Better than IAS or Mach getting close to the terminal as TAS will vary with either level or temp and therefore GS is affected.

[Keg]

For enroute stuff (IE, last couple of hundred miles of cruise), I can do groundspeed with no dramas. On descent, groundspeed is more work to maintain and an IAS is preferred. I can 'do' g/s if you want but the IAS is the preferred method for me once we start the descent.

[MAXX]

MAC on the early part of decent thence IAS is pretty much the normal and obviously much easier for the pilot to achieve.
G/S can change quite dramaticaly up high from initial decent due to enviromental changes.(jetstreams etc)

Maintaining a ground speed in the crz and intial descent i believe is a little urealistic to be a standard.