Any Unknown or Unlisted Aircraft Manufacturer
Air Traffic Control Fully Certified
Communication Breakdown; Other / Unknown
ATC Issue All Types
General None Reported / Taken
ATC Equipment / Nav Facility / Buildings
An IFR aircraft operating at 11;000 FT reported GPS issues originally but seemed to be working fine when asked for a position report; however we unexpectedly lost RADAR at said altitude in an area where radio and RADAR are very limited. Pilot was informed RADAR contact was lost and he reported level flight and his position. I put the aircraft into coast track only when I tried to set his track first it didn't update and ended up around 15-20 miles behind where he reported. Pilot was also moving much faster then where his 'coast' flight path indicated. He had; as we came to find out later; lost his transponder and had to recycle it which is how we found him; however he was already around 20 miles into the next sectors airspace when he popped back on RADAR. Prior to asking pilot to reset his transponder we tried to call him around 12-13 times but were unable to receive a reply due to the fact he had moved beyond our radio coverage so were unable to get any reports on his position or make any attempts to ask him to reset his transponder since we could update where he is and coordinate with the next sector any information other then that he was for our purposes lost. We couldn't talk to him or see him on RADAR other then as we found later review a primary only target however even that was very intermittent and the airspace between the 2 sectors we were unable to even see his primary target on RADAR either. The pilot ended up calling on another frequency trying to re-establish communications with ATC and that's how he ended up on the next sectors frequency and finally able to get him to reset his transponder and finally see him on RADAR and re-identify him. Install better RADAR and radio transmitters so ATC is able to better establish communications and separation services for aircraft moving thru mountainous terrain so that at least in the event we lost RADAR we could still talk to the pilot or even better just not lose RADAR on aircraft operating around 5;000 FT above the MIA.
ZDV Controller described an airspace incursion event claiming the poor RADAR and radio coverage in the subject area was the primary cause of the airspace infraction.