Originally Posted by
BraceBrace
Turn it the other way around. If METAR says 11°C, and temperatures drop 1°C... you're not going to use engine anti-ice because METAR says so?
No. If it dropped another one to 9° C I would because the AFM and my boss say so if there was visible moisture with VIS <1600m or precipitation.
Something to do with airflow over the inlet lip, namely at the rated take-off air-guzzling thrust and the subsequent drop of local temperature where heating is so kindly installed. Guess we must have paid for that....