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747 rotates way down the runway

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You can see the 747 rotating and climbing just as the 1000 foot markers go by.
 
FlyChicaga said:
I think I know what Burritos is talking about. It's an old rule of thumb-type thing that if you are taking off into suspected windshear, you bump your speeds up to the max speed for the runway restriction weight. So lets say your airplane weights 200,000 lbs, and your runway restriction/climb restriction is 300,000 lbs, you use speeds for 300,000 lbs (or your max takeoff weight if it's lower). You also use the maximum thrust setting available (no thrust reduction). Then you'll rotate a little farther down the runway, at a higher speed. Now, you also can climb at a lower deck angle should obstacle clearance allow. This extra speed above Vs will provide you with some potential energy, which can be transfered into kinetic energy should you encounter windshear.

If I remember correctly you are pretty much on target except for the where I highlighted.

You still use (bug) the speeds for your actual weight but aim to rotate at whatever "optimized" V1 speed you have for the runway you are using. Say you're taking off and your speeds are 140, 140 155, and 170 for V1, Vr, V2 and Vt. The optimized V1 for your runway in the runway analysis is 154. (Made up numbers) You would still bug your speeds the same as always but would plan to rotate at 154 if the plane hasn't begun to rotate by then on it's own. (You don't want to hold the plane on the ground if it wants to fly.) With this method you'll still have your balanced field performance at that higher V1 and but will have more of a speed cushion in the event of windshear.

I haven't done this since my last PC in April, but if memory serves that's how it works at ASA. I'm sure I'll be corrected if I'm wrong.
 
Except, since you're talking about a 747, the BOW is going to hover around 400k, TOGW will be significantly bigger numbers. Heck, an MD11 empty weighs over 250k!
 
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.
 
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.
 
Thedude said:
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.
 
Agreed

Mmmmmm Burritos said:
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.
 
Thedude said:
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.
 
Redmeat said:
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.
 

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