During non daylight saving times YSSY allows a couple of early morning arrivals (between 0500 - 0600) prior to the end of curfew onto RWY 34L. These arrivals use 'zero reverse thrust'. This also happens during quiet times arrivals onto RWY34L. Under both scenarios the arriving aircraft can, subject to no aircraft departing off RWY 34L, roll through the intersection of RWY's 07/25 and exit RWY34L onto a taxiway left closest to Gate 9/10 for international arrivals and similarly to the right for domestic arrivals. Many years ago when QF were routing their 744 and A380 flights QF9/10 flights through SIN these arrivals into LHR would be between 0500 and 0600. Similarly they arrivals would also use 'zero reverse thrust'.
Operations with idle reverse are generally mandated at the airports that have shoulder noise issues. At some places (London) we'll try to use idle for any early movements, even if not required.
The question is, under the scenarios above, does ATC request jet arrivals to use 'zero reverse thrust' or is this mandated as part of the early morning arrival procedures into these airports? How is 'zero reverse thrust' selected? Can the PIC adjust the power of the reverse thrust or is it simply reverse thrust or no reverse thrust?
ATC doesn't tell us how to fly the aircraft. We're expected to know the rules, and to follow them. ATC are all about safe aircraft movements, not about policing noise policies.
Reverse thrust is selected by moving your hand over the top of the thrust levers, where there's another short set of levers which control the engines when in reverse. Picture of the 777 installation here:
Boeing 777: Thrust Controls
Once you have touched down, and the thrust levers are closed, you reach over the top to the reverse thrust levers and pull them up. That takes you to what is called the interlock. This is where the engine cowls move into their reverse positions. Once they are there, the electronic locks on the reverse thrust levers are released, and you can pull the levers past the interlock, which causes the engines to spool up (in reverse). There is a full range of movement, and you can take anything from idle reverse (by not going past the interlock position) to full reverse. Full reverse is not the same as full power...the engines are limited to something around 85-90%.
We always go to the interlock (idle reverse). Any noise policy issues are covered by not going beyond that.
On the big engines, reverse thrust is a bit of a misnomer. There is very little reverse thrust. All that happens is that the cowls and blocker doors move in such a way as to blast the fan air radially out around the engine, and not let it pass out to the back as normally happens. The component of this vector that is forward is trivial. The core, hot air, is unaffected, and continues to produce forward thrust. The overall effect of reverse might be a few thousand pounds of thrust, but the major contributions are the cancellation of the core's forward thrust, and also the blast effect on wet runways which helps braking.
There's always a set of rules in the manuals with regard to the use of idle reverse. In our case we have to have a certain level of braking available (i.e. the runway can't be slippery), no faults that affect landing performance, and the runway performance calculation must have be done without reverse thrust. An airline may simply mandate a certain level of excess length. It will be allowed for somehow in the calculations though. Because we always go to the idle reverse position, it means that if something goes wrong during the landing, full reverse is instantly available if needed.
With the roll through on RWY34L in YSSY is this something requested by the PIC on arrival or is it typically offered up by the TWR along with the landing clearance?
Tower knows where you are going, and will offer a roll through if they can.
As an aside I've noticed when the domestic guys on the 737's roll through to the end of RWY34L it sometimes appears the aircraft speed on the runaway may be a little excessive as the brakes get a bit of workout when looking to exit onto a taxiway to take you to the domestic terminal. I've also noticed for the last 12/24+ months the Dash 8's don't seem to use the roll through anymore when using RWY34L?. Is the roll through some the company can mandate that is rejected to safety concerns or do they leave it up to the PIC?
It's always hard to judge things from the cabin. The braking comes as a surprise, as the aircraft has been rolling along for quite some time with no braking at all, and then even moderate will feel extreme. Carbon brakes also respond better to fairly heavy applications rather than very light but long period braking.
Roll through isn't something that companies would say much about, as it's to their benefit. I can't see a reason to knock back a roll through.