Role of Tropopause Entry in the A320 MCDU

As the temperature stops decreasing at the tropopause, aircraft performance sees a favorable turn. Staying below this threshold becomes advantageous, particularly for aircraft like the A320, tailored for short to medium flights.

Entering the tropopause in the MCDU is essential for adjusting the Flight Management and Guidance Computer (FMGC) temperature model to accommodate non-standard temperatures. This adjustment is crucial for enhancing performance predictions by ensuring a more accurate temperature representation.

The FMGC relies on a temperature model based on the International Standard Atmosphere (ISA). However, real-world conditions often deviate from this standard. By updating the tropopause altitude in the MCDU and inputting the cruise altitude and temperature, the temperature model can be adjusted closer to the actual conditions experienced during flight. This refinement leads to more precise performance predictions.

In summary, accurately inputting tropopause and cruise altitude/temperature values into the MCDU is crucial for optimizing performance predictions and ensuring safe and efficient flight operations.

What value of tropopause should be entered in MCDU?

To streamline operations, leaving the autotune function activated in the Multipurpose Control and Display Unit (MCDU) serves as a convenient practice. Some operators also advice to put highest available value on tropopause in MCDU.

However, when it comes to the A330-223 equipped with Pratt and Whitney engines, a notable caveat arises. Here, a precautionary note advises against altering the default value of 30690.

Neglecting to enter either the tropopause or cruise altitude/temperature values results in predictions based solely on the ISA model. This approach diminishes the accuracy of predictions, except in rare cases where the actual weather coincidentally aligns with the ISA standards.

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