I always calculated my TAS at any cruise altitude by
- Using my planned cruise (pressure) altitude, temperature
- Plug desired CAS, PA, temperature into e6b and get TAS
But I've also seen people get TAS only from the POH for cruise. And many books say that e6b is only used for TOC and that for cruise you should use the POH.
The discrepancy I see is that the POH assumes a constant power setting. But I'm assuming a constant CAS. So, in that case it seems my way should be more accurate.
What's the proper procedure that a student pilot should follow?
p.s. I fly a pa-28-181.