The weight of the Emirates aircraft was still within its operational envelope, but take-off thrust is calculated so that V1, VR and V2 are achieved along a linear distance that allows the machine to comfortably leave the ground before the end of the runway. So, if they're heavy and on a short runway, they will need more thrust than if they're light, on a long one. The aim is to take off with as little thrust as is needed, because thrust = fuel consumption and noise disturbance for people on the ground. Of course, it would have been far different if the plane had actually been too heavy to take off under any circumstances.
Besides weight, there is also a question of weight distribution and centre of gravity. In one particular case, a flight with a stop-over in which the passengers and their luggage destined for the interim destination had been loaded together in a particular section of the aircraft and then disembarked there, without redistribution of the remaining weight or passengers led to the aircraft stalling upon taking off again.
In the Bagram military aircraft disaster, a 747 transporting military vehicles stalled on take-off when one of the vehicles it was carrying broke loose from its mooring, shifting a huge weight to the back of the aircraft that no amount of trim could compensate for. (https://www.youtube.com/watch?v=hvZEr3IkLJI&pp=ygUObWVudG91ciBiYWdyYW0%3D)
In the private flight that killed singer Aaliyah (https://www.youtube.com/watch?v=Lw0QFlzBQYg&pp=ygUObWVudG91ciBzaW5nZXI%3D) the pilot's error was simply overloading the plane with too much technical equipment and putting the burly security guys at the back of the plane. Everyone died because the singer was in too much of a hurry to calculate a proper weight distribution and tell her "that speaker stays here".
It’s amazing that a +/- 20% error in the weight data didn’t cause a more serious problem.
The weight of the Emirates aircraft was still within its operational envelope, but take-off thrust is calculated so that V1, VR and V2 are achieved along a linear distance that allows the machine to comfortably leave the ground before the end of the runway. So, if they're heavy and on a short runway, they will need more thrust than if they're light, on a long one. The aim is to take off with as little thrust as is needed, because thrust = fuel consumption and noise disturbance for people on the ground. Of course, it would have been far different if the plane had actually been too heavy to take off under any circumstances.
Besides weight, there is also a question of weight distribution and centre of gravity. In one particular case, a flight with a stop-over in which the passengers and their luggage destined for the interim destination had been loaded together in a particular section of the aircraft and then disembarked there, without redistribution of the remaining weight or passengers led to the aircraft stalling upon taking off again.
In the Bagram military aircraft disaster, a 747 transporting military vehicles stalled on take-off when one of the vehicles it was carrying broke loose from its mooring, shifting a huge weight to the back of the aircraft that no amount of trim could compensate for. (https://www.youtube.com/watch?v=hvZEr3IkLJI&pp=ygUObWVudG91ciBiYWdyYW0%3D)
In the private flight that killed singer Aaliyah (https://www.youtube.com/watch?v=Lw0QFlzBQYg&pp=ygUObWVudG91ciBzaW5nZXI%3D) the pilot's error was simply overloading the plane with too much technical equipment and putting the burly security guys at the back of the plane. Everyone died because the singer was in too much of a hurry to calculate a proper weight distribution and tell her "that speaker stays here".