747 rotates way down the runway

[Redmeat]

I am currently in new hire training for the 747 and the MGTOW is 833,000# with the avg BOW of 347,000#. Our company manual does not allow the 747 a higher V1 or Vr due to windshear but does suggest adding +25 to V2.

That is because V2 is an airborne airspeed. Your company probably does not have overspeed procedures.

 

[aeronautic1]

Agreed

That's normal. Sometimes jets stay on the runway longer to accelerate for gusting winds or something. I'm sure the 747's V1 speed was attained about halfway down that runway. It's just easier to accelerate down a runway than it is to acceleratee during climb out. Extra speed is good when the winds are crazy.

Looking at the weather in this vid, I would have probably done the same. I mean, when he rotated, he came right off the ground. More like V2.

 

[SkyBoy1981]

deleted

 

[Boeing747Driver]

I am currently in new hire training for the 747 and the MGTOW is 833,000# with the avg BOW of 347,000#. Our company manual does not allow the 747 a higher V1 or Vr due to windshear but does suggest adding +25 to V2.

When I was flying the 747 we could adjust V1 to the max allowed for that runway for windshear. So if you took off at at 780,000 you could use the numbers for 833,000 if the runway allowed it.

 

[shamrock]

Do any of you guys fly transport jets? YES, the proper term for what all of you have been talking about is called "overspeed". There is a graph for overspeed settings on the speed cards to bump up all speeds. The reason is for obstacle clearance, not wind shear. Extra acceleration on the runway gives you a better second segment climb. Alot of company's are not approved for this type of operation though. Company's that fly in mountainous terrain depend on it.

Thanks for the clarification, but the method I described in my previous post is for windshear, not obstacle clearance.

 

[FN FAL]

Thanks for the clarification, but the method I described in my previous post is for windshear, not obstacle clearance.

What's the difference?

 

[AA717driver]

I ain't the slickest guy when it comes to performance but I do know that if you don't pull back on the stick when the other guy says "Vr" or "rotate" and you blow a tire or suck in a bird or anything happens that would get the company to check the FDR, you're in a heap o' trouble.

With windshear present, you go rated thrust and maybe add to V2. You shure as he!! don't hold it on the runway longer. At least big planes work that way... TC

 

[shamrock]

I ain't the slickest guy when it comes to performance but I do know that if you don't pull back on the stick when the other guy says "Vr" or "rotate" and you blow a tire or suck in a bird or anything happens that would get the company to check the FDR, you're in a heap o' trouble.

With windshear present, you go rated thrust and maybe add to V2. You shure as he!! don't hold it on the runway longer. At least big planes work that way... TC

Tell that to the training department at ASA. Allowing the plane to accelerate (not "holding it on") to the higher V1 in windshear conditions is a trained procedure here. It's rarely used, but it is trained.

 

[Redmeat]

I ain't the slickest guy when it comes to performance but I do know that if you don't pull back on the stick when the other guy says "Vr" or "rotate" and you blow a tire or suck in a bird or anything happens that would get the company to check the FDR, you're in a heap o' trouble.

With windshear present, you go rated thrust and maybe add to V2. You shure as he!! don't hold it on the runway longer. At least big planes work that way... TC

Thank-you, yes it is strictly an obstacle clearance procedure. Windshear is 15 degrees nose up and ride the stick shaker, not lower the nose and go faster (to the ground). "overspeed" is basically a "zoom climb" from the runway.

 

[shamrock]

What's the difference?

Sorry, I'm not following what you are asking about, but I was simply replying to redmeat's declaration that the procedure is used for obstacle clearance, NOT windshear. That, along with wondering if any of us fly transport jets and correcting us about the proper name for the procedure came across as a bit condescending to me. Maybe I misunderstood his post.

Sounds to me like we are talking about 2 different procedures here.

 

[KeroseneSnorter]

Tell that to the training department at ASA. Allowing the plane to accelerate (not "holding it on") to the higher V1 in windshear conditions is a trained procedure here. It's rarely used, but it is trained.

I have never seen that procedure on anything of any size. Not saying that there is not one out there somewhere, but we are kind of comparing apples to oranges. After all the 74 hauls the full gross weight of 4+ RJ's just in fuel.

Kind of hard to compare an RJ to an 833k pound 747.

Most of the time at freight hauling weights we are using all the runway, no room left over to hold it on for more speed. Even a passenger hauling 74 is pretty light compared to a freighter.

 

[shamrock]

I have never seen that procedure on anything of any size. Not saying that there is not one out there somewhere, but we are kind of comparing apples to oranges. After all the 74 hauls the full gross weight of 4+ RJ's just in fuel.

Kind of hard to compare an RJ to an 833k pound 747.

Most of the time at freight hauling weights we are using all the runway, no room left over to hold it on for more speed. Even a passenger hauling 74 is pretty light compared to a freighter.

Point taken. I really wasn't trying to compare an RJ to a 747, just pointing out that a technique ASA uses for windshear is similar to one that was referred to in an earlier post.

 

[KeroseneSnorter]

Point taken. I really wasn't trying to compare an RJ to a 747, just pointing out that a technique ASA uses for windshear is similar to one that was referred to in an earlier post.

I can see where it would be advantagous in gusty conditions. I have never seen the procedure used. About the only thing that I can think of that comes close to it is a modified v1 speed for certian special runways (read short) to keep it legal. Although I cannot ever remember ever actually using that procedure. Current job does not have anything like it. Speeds for flap settings and weight and that is it, no change for any wind considerations, other than adjusting runway required etc.

 

[Singlecoil]

Where I work, the procedure for windshear is to bug for current weight, but rotate at the speed for the runway/climb limit weight for that runway under those conditions. That is for 737's and MD-80's.

 

[shamrock]

Where I work, the procedure for windshear is to bug for current weight, but rotate at the speed for the runway/climb limit weight for that runway under those conditions. That is for 737's and MD-80's.

Yeah, what he said!

That therz what I've been tryin ta 'splain but my Community Colidge educashun has faled me!