On Wednesday, January 23, 2019 at 10:19:56 AM UTC-7, wrote:
On Sunday, January 6, 2019 at 10:15:39 AM UTC-8, Darryl Ramm wrote:
Yes better be differential, have the right trip point, tolerance, longevity, and some basis for knowing the thing is suitable to install in an aircraft in critical pitot plumbing... or... I know pay $125 for the Pereguine kit and spend time worrying about more important stuff.

Is a pitot pressure switch required for a TABS installation in an experimental glider?

From what I read in the TSO-C199 describing requirements for TABS is that an 'automatic means of selecting the air/ground state is recommended'....BUT....'if an automatic means is not implemented, the transponder SHALL ensure that the air/ground state is Airborne'

So the answer appears to be no, the pressure switch is not required for any aircraft without an electrical system that are voluntarily equipped for TABS. But, I am not a lawyer.