On Tuesday, January 20, 2015 at 4:26:05 PM UTC-8, Dave Springford wrote:
It is my understanding that EASA approval exists for connecting non-certified GPS to mode S transponders to generate the ADS-B out data. In particular, the Garrecht VT-01 is approved in this manner and I think the Trig as well.

Since there are reciprocal agreements between EASA and other CAA's, the EASA approval should allow this practice in countries that reciprocate with EASA.

In a word NO. In two words HELL NO.

The NEMA GPS source used by a VT-01 does not meet any RTCA or EASA specification, and neither is is required to for it's intended (glider/light aircraft VFR) use in Europe.

There is no specific EASA requirement the VT-01 is required to meet for it's intended use, and in general it's worth being aware that EASA does not have an equivalent to the blanket FAA ADS-B mandate that is coming in 2020 (which gliders are exempt from). The relevant starting point is EASA AMC 20-24 (2008) which requires fit in new aircraft starting 2015 and retrofit in existing aircraft by 2017. But this *only* affects aircraft with MTOW greater than 5700kg or maximum cruising TAS greater than 250kts.

So there is no approval this meets, there is no relevant reciprocal agreement (reciprocity of ADS-B requirements for airliners etc. in EASA and the FAA is a long seperate discussion...), there is no nothing, there is no way any NEMA GPS source can meet the current FAA ADS-B Out GPS source requirements. And again, if you want to understand ADS-B Out approval in the USA start at FAA AC 20-165A.