Why is it that after take-off (climb), you climb with Vref+100 knots?

Question

well just looling at the first two answers: This is what i read concerning my question: http://i213.photobucket.com/albums/cc115/PilotFerdi/tz.jpg

Now, if Vref of a heavy B747 is about 170 knots, your climb speed would be 270 knots (because Vref + 100 knots).

Answer 1

Uhmm. Folks. Listen up. Vref is  the approach speed. It's calculated for landing depending on landing weight. I agree the that it is used in the initital go around (landing climb) but Vref is only appropriate with gear down and full flaps. Vref + 100 kts and your going to have some major, major flap maintenance bills. C'mon folks if you don't know the answer don't guess. Jeez.

You got it right anyway captain j. Man I hope the rest of you aren't actually flying transport aircraft.

Not even close Raphael G.

Answer 2

The short answer to your question: you climb to Vref+100 to get yourself outside of the dead man's curve, (low airspeed+low altittude+high climb rate), in case an emergency develops during the critical take-off phase.

Answer 3

Yes, sometimes you hear B747s advising ATC that they need to exceed 250 knots in the climb.

Answer 4

Vref+100? .....ummm...no...

Generally this is how you will take off.....

V1- Take off decision speed (Go - No Go Decision Time)

Vr- Rotate..(increase back pressure to raise the nose)

V2- Take off safety speed (depending on the terrain, you will do somewhere between this and your max speed for the airspace you are in)

I generally get airborne...positive rate...V2...Vfto-(final take-off speed)  flaps up...accelerate to 200 knots for the speed limit....then 250 once in the clear......

On an approach/ go around you will be looking for Vref+10 on your initial speed...(especially single engine go around)

Anyway, hope this helps...

Jonathan S

ATP-LRJET,HS-125,G-V

CFI/AGI

Answer 5

well it's actually a little bit scary that people who claim to be commercial pilots do not really have some specific knowledge. I also have learned it so that (and now, I am specifying on a B744, by the way there is someone called something like "aviophage....", who claims to be a 747-pilot, she could answer that question too) at first, you climb with V2+10 knots, and when you reach the flap reduction altitude (which lies often at around 1500 ft), you accelerate, typically to a maximum of 250 knots (because of the restriction under 10,000 ft).....However, Boeing 747 make it in this way that they climb or accelerate to Vref+100 knots (Vref is easily found with the approach page of the FMC). But Vref is just a reference, of course you would not take it for real landing, because you are much too heavy.....So, a full B747 with a mass of 390 tons would have a Vref of about 180 knots with this weight, so if you make 180 knots (Vref) + 100 knots, it means you accelerate then to 280 knots, so 30 knots faster than the 250 knots.....Of course, you have to notify ATC first that you wanna be faster.

Now, of course, if your flying learjets or smaller 737's, you won't have this problem, because you will not exceed 250 knots in any case=).

Answer 6

100 knots????...maybe 10!...probably for wind or de-icing reasons...

Answer 7

30REF+100 knots provides the best climb gradient for a given weight and thrust performance.

Also, it provides minimum drag and best fuel economy for a non cruise flight environment.

(good question by the way).