what doesn't make sense is the clearance "at or above 2,000'" when the plane was in an area where the MIA was 4,000 or 5,000.
My reading is that ATC gave that clearance while the aircraft was still in the southeasterly swath near the coast where the MIA is 2,000. It was heading towards higher terrain, but not yet in that part of the chart.
My reading is also (for the moment, pending further details) that both the controller and the crew lost situational awareness - they didn't notice that the terrain situation was going to change rapidly in the near future.
I don't know for certain what information the controller had (or should have had) in front of him - I presume that will come out eventually. I
do know what information the pilot had (or should have had) in front of him - and it is a chart that in TWO places says, "If you are going northeast of ZEDAG, you
must be at 4300 feet to remain safe!"
Given two advisories that do not actually conflict:
ATC - "at least 2000 feet or higher"
Chart - "at least 4300 feet"
- which altitude would/should a pilot choose?
This may be of interest - although it does not go very far in clarifying the situation:
A flightcrew should be generally aware of terrain and obstruction elevations and should never accept instructions that do not ensure adequate terrain clearance. A controller is required to issue a safety alert to an aircraft if the controller is aware the aircraft is in a position/attitude that, in his/her judgment, places the aircraft in unsafe proximity to terrain or obstructions. Air traffic controllers issuing specific altitude instructions and clearances accept responsibility for terrain avoidance.
Pilot charts depict minimum en route altitudes, minimum obstruction clearance altitudes, off route obstruction clearance altitudes, and other altitudes. Minimum vectoring altitudes, available only to ATC, can sometimes be the best and lowest altitudes available for instrument flight. Pilots receiving altitude assignments below charted altitudes typically assume they are being assigned the minimum vectoring altitude.
Source:
U