747-400 Vref question (30 Ref)

[RPRIEVER 52]

Greetings all,I've been reading the flight sim version of Tolstoy's "War and Peace", aka: the PMDG 747-400x manual. A LOT of reading. I have a question about V speeds. I'm pretty familiar with V1, V2, and Vref, but I'm not sure about something called "30ref". In the climb modes section, it indicates you should climb at "30ref +100" What exactly does the "30" signify? Obviously, I should be climbing at 100kts plus whatever "30ref" is, but I'm stumped as to what that is. Thanks for your help.Ron

[FLEX1978 373]

Hi Ron,REF 30 and REF 25 are landing speeds depending on what flap setting you choose,these can be found on the APPROACH REF Page on the FMC. Flap 25 is normaly used unless your landing near Max weight but it all depends on what airline you fly with. you would also make adjustments for wind additives eg add half the headwind speed to your landing speed. so if the runway is 360 degrees and the wind is 360/16 your speed would be VREF + 8 knots.On Departure You should use the following speeds. However if your flying under VNAV the Aircaft does the hard work for you :)Flaps up you should maintain VREF 30 + 100 knotsFlaps 1 VREF 30 + 60 knotsFlaps 5 VREF 30 + 40 knots Flaps 10 VREF 30 + 20 knots ( Light Departure)Flaps 20 VREF 30 + 10 knots ( Heavy Normal ops) Flaps 25 VREF 25 (Landing speed in FMC)Flaps 30 VREF 30 (Landing speed in FMC)Rob