cold weather

I recently purchased a 1979 Piper Dakota with a Lycoming O-540. This plane lived in Newark for a long time, and had at least one cold-weather mod--an engine heater. I picked up the plane from Newark in April. It was very cold there. During the 10 hour trip to Louisiana, the engine monitor...

i am a little confused about ATC and cold weather adjustments. I understand the concept of how your altitude is lower than indicated when in colder than ISA but... in the Instrument Flying Handbook they explain that if you apply adjustments for cold weather you should let ATC know you are doing...