On Monday, March 5, 2018 at 11:48:06 AM UTC-8, wrote:
How do current certified loggers determine altitude? Being some are plumbed to external pitot/static and some are cockpit pressure only, what differences are expected?

Does your mechanical altimeter (especially 57mm size) read close to your "glide caculator" altitude?

Are loggers solely dependent on pressure altitudes or is GPS altitude comparison ever included in the algorithms?

Seems one would be more likely to "bust" min/max altitudes using cockpit pressure loggers.

As a sanity check, full pitot pressure at 60 knots is around 0.085 psi. A foot of altitude depends on altitude but call it 0.0004 psi below 18,000 ft. So if you could get full dynamic pressure in the cockpit at 60 knots your recorder would be off by 200 ft. It should actually be a small fraction of that.