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747 rotates way down the runway

wheelsup

Non-Registered User
Very cool

Thats not an illusion, that was a close one. Caution wake turbulence! Great video thanks for the link.
 

cj610

Well-known member
We were taking off out of Gander one day. The tower told the guys working at the end of the runway that a Heavy 747 was taking off. The construction guys said 'go ahead, we will be alright". We started our takeoff, once we crossed the hump in the middle of the runway we could see the workers and tractor down at the end. Our takeoff was just like the one in that video. When we got just beyond 4/5 down the runway there were workers and tractors running everywhere. It had to have been f'n loud when we went over. I bet they moved next time a heavy took off.

CJ610
 

Mmmmmm Burritos

Where mah dogs at?
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.
 

scangadah

Well-known member
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.
What the hell is in your burrito....Crack?
 

Mmmmmm Burritos

Where mah dogs at?
It's true. It's in our company's POH and in training to do that when you have suspected windshear on takeoff. If you rotate at Vr and suddenly get a loss of 30 kts airspeed due to windshear, you're pretty much screwed. But if you stayed on the runway and accelerated 20 kts or so past V1 then you'll probably be fine. That's of course if there isn't much terrain in front of you to climb over.

Of course in that video we have no idea what they're really doing.
 

Peanut gallery

Well-known member
Total normal takeoff

Looks completely normal for a widebody four engine airplane. In fact I would suggest that seeing it leave the ground it is probably well below both gross weight and numbers for that particular runway. I'm with the other guy what kind of crack is in your burrito.
 
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KeroseneSnorter

Robust Member
He was probably on speed, From the time you start to rotate a 747 and when the mains actually leave the runway is in the neighborhood of 2000 feet or so. When heavy on that puppy you do not have the luxury to wait a bit longer, most of the time it's Vr or the end of the runway....whichever comes first! :)

Get it heavy enough and there can be enough time between between V1 and VR to hold a short conversation about politics or whatever.......not that you do since that would violate the sterile cockpit!!:D
 

FlyChicaga

Well-known member
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.

Can't say I follow this rule myself, but I have read and hear about this from some older pilots. Makes some sense I'd say. If you are going to experience windshear, would you rather have a 1.3 margin above Vs, or a 1.5+ margin above Vs?

Check out the windshear section of "Fly the Wing" by Jim Webb.
 

shamrock

Well-known member
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.
 

profile

Shem Malmquist
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!
 

Redmeat

People Mover
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.
 

Thedude

Well-known member
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.
 

Redmeat

People Mover
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.
 

aeronautic1

Virgil_Tracy
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.
 

Boeing747Driver

Nitromethane
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.
 

shamrock

Well-known member
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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