flaps, descent speed

See if this is of any help.

https://forum.flyawaysimulation.com/forum/topic/8080/ils-approach-guide-tutorial/

Your speed should be anything under 250kts below 10,000ft. And on approach you should decend your flaps at or around 15 miles so when you're at about 10 miles, you should decend smoothly into the runway. I reconmend on your Final approach for a heavy jet (777 or 747) your speed to be about 138kts while decending.

Yeps for 747 the speed should be around 138-145 knots as the aircraft stalls at 135 knots....

1. Approach speed for the default 747-400 ( from FS data)

Boeing 747-400 Microsoft Flight Simulator 2004
Vref Landing Speeds

Weight-Lbs./speed (KIAS) Flaps 30

880,000 /181
837,000 /176
794,000 /171
751,000 /165
708,000 /160
665,000 /155
622,000 /150
579,000 /145
536,000 /139
493,000 /134
450,000 /129

Weights are in pounds and speed is in knots indicated airspeed (KIAS)
Flaps 30 for all weights. I hope that it helps.

2. what speed for Top of descent(TOD)?
The TOD for a 747 would be very high, you would descend at you cruising speed(Mach) until the transition to indicated speed(approx. FL280).
Example:
Cruise altitude until approximatlly FL280-----.80 Mach
FL280-10,000 feet MSL-------------------------300 KIAS
Below 10,000 feet MSL-------------------------250 KIAS

3. Speed at 25 miles out?
Depends on weight but ballpark figure, flaps 20, speed 210 KIAS.

4. What altitude would you lower flaps?
Normally a 747 uses a ILS. Flaps would be set to 30 degrees at or slightly before GS intercept. Approximately 2000 feet AGL.
🙂