IIRC the 747 Classic would actually decel to ground idle at TOD with a clean configuration. However as soon as flaps (or gear???) were extended, the donks would spool up to "approach idle"
Selecting landing lap (25 or 30) with the aircraft in flight will activate flight idle on the 747-200. And just as well: the CF6s especially take ages to spool up.
However, reducing to idle thrust at high altitude will not get you as low an N1 as you can achieve at lower altitude... I noticed this on my previous A/C as well, as you descend, idle N1 appears to decrease. Anyone know what the technical explanation is (while I go search for my anorak
)?
MD