ATCBob

No it was not a legal clearance and the controller violated the 7110.65 "in my personal opinion."

See the example (below) from 4-8-1-b-2 that shows specifically an approach clearance commencing at an IAF where the MVA is below the published altitude at the first segment (as was the case in this incident).



Both aircraft are direct LEFTT and the MVA here is 3000. Aircraft #1 is at 4,000 and the clearance here is to cross LEFTT at or above 3500 (note altitude on the first segment, not the MVA) and cleared the approach.

Aircraft #2 is at 3,000 but cannot be cleared the approach commencing at LEFTT because they're below the altitude of the first segment, so to get them from LEFTT to CENTR (where the segment altitude is at 3,000) you have to clear them either direct CENTR, or in this example direct LEFTT direct CENTR and cleared the approach beginning at CENTR. (Not shown here you can also climb them to 3,500 to begin the approach at LEFTT, but the way they show is easier).

In this event, Skywest was either at or above 10,000 when the clearance was issued prior to the IAF so would have been the aircraft #1 example, where the controller was required to issue CEGAN at or above 10,000 (not the MVA of 7800).

Or Skywest was below 10,000 already prior to CEGAN in which case the controller could not issue the approach beginning at CEGAN without a crossing restriction at or above 10,000 (there's no other IAF on that approach with an altitude below 10,000).

So no, not a valid clearance.

Maybe the controller or his instructor came from a facility in a non-mountainous area where the MVA was always at or above the IAF altitudes and that's how he was taught to do it, and never encountered problems with this particular approach because the pilots always caught it. But the above requirements to issue an altitude at or above the IAF altitude is in the 7110.65 I'm sure to help prevent situations exactly like this.