A tail strike during take off occurs when the tail of the aircraft contacts the runway during or after rotation, typically because the pitch attitude exceeds the geometric clearance at the current speed and configuration. 

Safety data from Airbus and Boeing consistently identify INCORRECT PERFORMANCE CALCULATIONS as the leading cause of tail strikes: a wrong take off weight (data entry error, gross weight not updated), an incorrect flap setting, an incorrect Vr, or an incorrect stabiliser trim leads directly to rotation at inappropriate speed and attitude, producing the tail strike. 

Ensuring that the take off performance data are correctly computed and cross checked (weight, flap setting, V speeds, thrust, trim setting, runway condition, wind, temperature) is therefore the primary and most effective preventive action.

Reducing the rotation rate below the standard value (typically 2 to 3 degrees per second) is not correct: an excessive rotation rate must be avoided, but a rate that is too low is also detrimental. Adding a speed margin to Vr is not a standard preventive measure and can jeopardise runway length. 

Reduce rotation rate → INCORRECT. The rotation rate must be maintained at the CERTIFIED / recommended value, typically around 2 to 3 degrees per second. Rotating too quickly can cause a tail strike, but rotating too slowly is also detrimental (extended ground roll, delayed lift off, insufficient climb performance). Generically stating "reduce the rotation rate" is not a valid preventive action. The pilot must maintain the correct rate, neither too fast nor too slow.

Accurately calculate take off performance data → CORRECT. Erroneous performance data (incorrect take off weight, wrong flap setting, wrong Vr, incorrect stabiliser trim) is the leading cause of tail strikes on transport aircraft. Ensuring that the calculations are correct, cross checked between both pilots, and consistent with the actual take off conditions (runway, wind, weight, configuration) is the primary and most effective preventive action.

Add an increased speed margin onto rotation speed → INCORRECT. Adding a speed margin to Vr is not a standard operating practice. It can extend the take off run beyond the certified data, reducing the runway margin. The correct action is to use the ACCURATE Vr computed for the actual conditions, not to add an arbitrary margin.

Maintain a steep take off angle after rotation → INCORRECT. A steep take off angle immediately after rotation INCREASES the risk of tail strike, especially at low speed where the geometric clearance is smallest. The correct technique is to maintain a controlled and moderate pitch attitude, typically defined by the flight director bar (usually around 12 to 15 degrees, depending on the aircraft).