Takeoff Target N1%/EPR displayed on EICAS vs. Performance vendor calculated values
Hello,
I am wondering if any operators have specific tolerances for variation between the aircraft's calculated target N1 or EPR value for a given takeoff thrust setting compared to the calculated N1/EPR that comes from the performance vendor or performance chart. My current operator instructs us to compare the numbers for reasonability but stops short of assigning a value beyond which the difference is unreasonable. The usual culprit in large variance are temperature discrepancies between ATIS/Metar temps used by the performance calculator compared to the temperatures being sensed by the thermometers in the aeroplane. At what point would you halt the operation over such a discrepancy? 1%? 2%? 5%? How would you attempt to remedy the situation? Force maximum thrust?