Why might EPR indications increase falsely during takeoff?

The correct answer focuses on the phenomenon related to iced P sub T probe vents. During takeoff, if the P sub T (total pressure) probe vents become iced over, they can deliver incorrect pressure readings. This can cause a false increase in the Engine Pressure Ratio (EPR) indications. The EPR measurement is derived from the total pressure at the inlet and at the exhaust, and if ice obstructs the vents of the P sub T sensors, the pressure measured may not accurately represent the true performance of the engine. This distortion can lead to incorrect readings, giving the impression that the engines are producing more thrust than they actually are.

In contrast, other factors such as engine power levels or fuel pressure do not directly affect the EPR indication in the same manner. While low power settings might affect performance, they wouldn’t specifically cause a false increase in EPR readings. Similarly, incorrect gauge calibration would typically lead to consistent wrong readings rather than a false increase under particular conditions like takeoff.