Originally Posted by
rickair7777
But I don't think awareness of the stepdown altitudes was the problem. I think the problems were...
- Assuming that they were good down to 7800 based on an MVA.
- Lack of awareness of actual terrain (this is all on them).
When I worked there, I could have gotten sucked into this right up until that last part... I like to read the terrain highlights on approach plates... especially doing DME arcs to a VOR approach in mountains in IMC.
MVA at Cegan is 7,800, which is apparently why the controller issued such a dangerous clearance, but the controller shouldn't have done it unless he or she intended to provide vectors and terrain clearance continuously. MVA is, after all, for vectoring. To assign an altitude at the MVA, or even suggest it as part of a clearance when a vector is not part of the assignment, is setting the crew up. Very dangerous.
A firefighting operator (no longer in business) that used P-3's accepted a dispatch to Missoula a number of years ago. Conditions required the use of an approach at Missoula. The nature of that kind of operation means very short notice dispatches or diversions; it's a constant thing. On arrival, the crew found that they did not have a printed chart for the procedure, and ATC provided it for them verbally.
Without the ability to see the procedure in front of them, they did not have the situational awareness. The arc at Missoula arrives to final from two directions, at two altitudes. They were fine at their arrival altitude on the arc, and fine if they made the correct turn to final and completed the approach. They were not fine if they missed the turn and continued on the arc into rising terrain, which is what happened. The altitude worked for one segment of the approach, but not all...much like an MVA in the case of the procedure in this thread, which was acceptable at CEGAN perhaps, but not for the remainder of the procedure.
The two cases are not identical, but do draw on some salient points. The procedure doesn't help much if not followed. The diagram and details aren't much use if not used. While an ATC clearance should be flown when received, the old adage to trust but verify seems cogent. The entire procedure should be reviewed, particularly in mountainous terrain.
Deviations from published procedures, even on vectors, can be invitations for Murphy. We got vectors to the procedure in Kabul one night, which means off course in very tall mountainous terrain. It ought not be a problem, but heavy jamming was taking place with difficult communications; ATC was in and out. At some point, we lost all electrical, dark cockpit, loss of displays. We found ourselves going to memory items then trying to rebuild the system by checklist, and unable to copy additional vectors, with other aircraft nearby. Dominos. At what point, when accepting deviations from what's published, or even when getting to what's published, do we find the gates starting to close? At the point it becomes critical to know the high points, know the terrain, and know the details, it's already too late to begin looking it up. Hence prebriefing.
Ultimately, all that could have been avoided here by simply flying the published procedure in accordance with the clearance, which was "at or above 7,800." 10,000 on the arc is at or above, and hides a multitude of sins.