On the rare occasions when I am able to say "no ATC speed control" to someone on final approach it's more than evens that he will fly much faster than one of our "standard" speeds
Lots of reasons.. If there is no ATC, no height or speed restrictions. The descent profile would be, Close the thrust levers at top of descent. Manage your speed, height, flight path, flaps and gear such that you spool up at 1000' aal in the landing configuration. ie. Thrust at idle from TOD to spool up. Very nice feeling if it all works out. Not too often with me! So 300kts at 20 miles 5000', bleed the speed off, run the flap, pop the gear, more flap and up comes the power. The speed is never static. On average it is faster and more efficient than with ATC speed controls. Some aeroplanes speed brakes are much more efficient than others. A "T" tail aeroplane has better speed brakes because the turbulance form the speed brakes does not impact the tailplane. So faster till later. The groundhugger let you deploy the reversers in flight. That slowed things up. So left to our own devices, the descent profile is very different to that witch ATC impose on us.
Why do so many 737s ask for 170kts to 4DME
The 737 has a fixed flap speed schedule. Flap 5 is flown at 170Kts. 160 needs Flap 10. Flap 10 is non standard. It should be after flap 5, Gear Down, Flap 15. And that is flown at 150 kts. Also a 737 will sit on a 3 degree slope at Flap 5, and 170kts and not accelerate, or decelerate... normally. Depends on the weight and the wind component. So for a 737 pilot 170kts is a good place to be.
Who was the BA pilot I met once who said he couldn't understand why we didn't always use 180 kts to 4DME
Indeed who is he! He sure never flew an A320/ 319s or a 747.
Lastly, I sympathise with you if the approach requires a lot of concentration but think about the final director - he doesn't just have to do it once; in one session he might land 50-60 of you guys and every single flight requires 110% concentration.
Eeeer this is a wind up? Yes? Or do you wish to open another thread entitled, "Pilots have it easy, ATC guys work for a living" We can deal with your point in that thread.
L337