3 ms·

Rotating at a slower speed is a bad idea. Indicating a lower weight, resulting in a lower calculated rotating speed, is the root cause of the problem. There is

Rotating at a slower speed is a bad idea. Indicating a lower weight, resulting in a lower calculated rotating speed, is the root cause of the problem. There is no "slower rotation", one does not just pull the yoke slowly, raise the nose wheel and wait for the plane to take off by itself when it will be fast enough, that you can do on a light prop plane where rotate speed is so low some planes will take off by themselves, but not on an airliner where you have a high chance that raising the nose too early results in speed not increasing or even decreasing.

dandandan 4y ago
I interpreted "slower" as "later," ie wait longer before rotating.
- AdrianB1 4y ago
  That means rotating at a higher speed than calculated Vr, this is also bad as you put more wear in the tires and use more fuel (rolling on the tires vs flying in the air) to take off. The Vr is an optimal speed, below is dangerous, above is wasteful.
  - mgsouth 4y ago
    I think the more important factor is that it eats runway and takes longer to reach safe speeds. If there is a problem at rotation you want as much runway available as possible. If you delay rotation not only are you further down the runway before "really rotating", but you're traveling faster. A 10-knot increase in speed means 20% more energy to disipate. And you're even further above the brake's certified performace. And you've dawdled in getting to safe climb speeds; you accelerate more slowly rolling than flying. Edit: Actually, that probably doesn't even come into it. Not a pilot, but don't imagine "barely rotate so the nosewheel is in the air but still have negative angle of attack so no lift" is very easy, or very stable if possible. Even if you could do it, you'd risk slamming the nosewheel back into the runway.
    - mnw21cam 4y ago
      V_r is almost always above V_1, which is the decision speed. If you're going to abort a takeoff, that decision needs to be made before V_1, otherwise you're likely to overrun the end of the runway. So, once you get to the stage where you're ready to rotate, or even late in rotating, you're committed to getting the plane off the ground.
      - wkat4242 4y ago
        On a big airliner yes. V1 depends on the runway length so a smaller aircraft will easily reach Vr before V1. Because most runways are made for the biggest planes.

dandandan 4y ago

I interpreted "slower" as "later," ie wait longer before rotating.

AdrianB1 4y ago
That means rotating at a higher speed than calculated Vr, this is also bad as you put more wear in the tires and use more fuel (rolling on the tires vs flying in the air) to take off. The Vr is an optimal speed, below is dangerous, above is wasteful.
- mgsouth 4y ago
  I think the more important factor is that it eats runway and takes longer to reach safe speeds. If there is a problem at rotation you want as much runway available as possible. If you delay rotation not only are you further down the runway before "really rotating", but you're traveling faster. A 10-knot increase in speed means 20% more energy to disipate. And you're even further above the brake's certified performace. And you've dawdled in getting to safe climb speeds; you accelerate more slowly rolling than flying. Edit: Actually, that probably doesn't even come into it. Not a pilot, but don't imagine "barely rotate so the nosewheel is in the air but still have negative angle of attack so no lift" is very easy, or very stable if possible. Even if you could do it, you'd risk slamming the nosewheel back into the runway.
  - mnw21cam 4y ago
    V_r is almost always above V_1, which is the decision speed. If you're going to abort a takeoff, that decision needs to be made before V_1, otherwise you're likely to overrun the end of the runway. So, once you get to the stage where you're ready to rotate, or even late in rotating, you're committed to getting the plane off the ground.
    - wkat4242 4y ago
      On a big airliner yes. V1 depends on the runway length so a smaller aircraft will easily reach Vr before V1. Because most runways are made for the biggest planes.