A pilot of a general aviation aircraft conducting instrument training flight into GZS conducting the RNAV (GPS) Runway 16 approach voiced concern regarding failed communications with ZME during the approach and missed approach phases.

Narrative

Conducting instrument training and cleared for GPS 16 GZS by ZME Center (125.85). Prior to switching to advisories; radio communications were loud and clear. Upon reaching MAP; aircraft was about 300 FT above MDA due to inadequate descent rate (training) and still in IMC. Immediately initiated missed approach but due to student workload was not able to attempt radio contact with ZME until about 4 NM southeast of the airport. By this point we were approximately 2000-2500 MSL; climbing to 3000 MSL (published altitude for missed approach procedure). Unable to establish radio contact on 125.85. Tried both radios; disabled radio squelch. We could faintly hear transmissions but could not discern their meaning or the intended aircraft. As we approached the missed approach holding point we were about to squawk 7600 and proceed with lost COMM procedure when we were both able to barely hear ZME clear us to 4000. Upon reaching 4000 radio communications were still very weak but we understood clearance direct to MQY (our alternate) and were instructed to switch to ZME center on 126.75. Radio communications were loud and clear on the new frequency and we proceeded back to MQY without any further problems. The published frequency for APP/DEP control for the GPS 16 at GZS does not appear to have adequate coverage for the entire IAP as we experienced difficulty during the missed approach segment. This is perhaps the worst segment of IFR flight to experience lost communications as 91.185 does not provide any guidance on leaving the clearance limit (missed approach holding point) for the purposes of proceeding to the alternate airport.