A Squared:
That may be, I haven't been on the other side of the scopes but from my side of the radio, it always seemed that radar was spotty at best below 5000 ft around Dillingham, that said, I've been called in contact at 2000 ft between Dillingham and King Salmon more than once.
I have also seen the Anchorage Center MIA maps for the area. The MIA is 2,000 until nearing Dillingham, where it becomes 4,000.
I can understand radar coverage being spotty north or west of Dillingham at 5,000. But, from the King Salmon center radar site on King Salmon Airport, it is 61.83 nm over flat terrain to ZEDAG. Normally, with flat terrain the radar should have no problem painting a secondary, if not primary return at ZEDAG at 2,000.
The pertinent part of the NTSB preliminary report states:
"According to Federal Aviation Administration (FAA) personnel, as the airplane approached Dillingham, the flight crew requested the RNAV GPS 19 instrument approach to the Dillingham Airport about 0757 from controllers at the Anchorage Air Route Traffic Control Center (ARTCC). The ARTCC specialist on duty subsequently granted the request by issuing the clearance, with instructions to proceed direct to the Initial Approach Fix (IAF) to begin the approach, and to maintain an altitude of 2,000 feet or above. A short time later the flight crew requested to enter a holding pattern at the IAF so that they could contact the Flight Service Station (FSS) for a runway conditions report, and the ARTCC specialist granted that request.
The ARTCC specialist then made several attempts to contact the aircraft, but was unsuccessful and subsequently lost radar track on the aircraft."
No doubt the crew's altitude awareness was poor. In fact, they had been inside the 5,400 TAA sector for RNAV 19 since 30 miles prior to ZEDAG. Then again, that really wasn't pertinent until they were cleared for the RNAV 19.
Nonetheless, a clearance below MIA and the apparent lack of an EMSAW alert has safety implications for the entire U.S. This is obviously lost on the NTSB.