john_tullamarine

Came across this thread whilst browsing. Either instrument is fine for in-aircraft use. The Dalton (E6B) probably is better in the cockpit for usage and accuracy, especially with slower aircraft. Yes, it's a tad bulky but not at all a problem. At ATPL level, the CR is preferred as almost all the Daltons don't have any temperature/airspeed corrections for higher Mach numbers. If you choose the CR, please ignore the admonitions about ETAS not being necessary as the drift angle reduces. The mathematically and geometrically correct answer for G/S ALWAYS involves calculation of ETAS, although, as the drift gets smaller, the difference between TAS/ETAS gets smaller and, for nil drift, ETAS=TAS. In the aircraft, it doesn't really matter but you will benefit from the increased accuracy for your CASA exams. Of more relevance, there is absolutely no benefit to using TAS in lieu of ETAS as, when you set up to figure the drift angle, the ETAS setting is automatically setup .. ie all it takes to figure ETAS is to switch your eyes from the sine scale (for drift angle calculations) over to the cosine scale and read it off against the drift angle. It's dead easy and quick, why would you bother playing about with rather silly approximations which offer no value ? I've used both from little aeroplanes up to airline jets and for theory training over many years. Either is fine but the Dalton, being alloy, is far more robust than the plastic CR. If you use the CR, you just need to be careful about where you leave it, considering ambient temperatures. What really surprises me is that none of the E6B clone manufacturers have adopted the Huber scales (which are on the CR). If the E6B had those, there would be no value in running with the CR, I suggest.