We are so used to getting clearances to descend below platform altitudes that most don't even flinch anymore...like driving it in at 4000 feet over Lake Michigan to O'Hare or being 20 miles out of ATL and getting 3000 feet (not depicted on any platform). GF |
This should be looked at as two clearances, the first was an enroute dir>cegan which requires an altitude at or above MEA/MCA. In this case MVA was used because they were off route and no MCA existed for the next segment being the IAP.
The second clearance was the for the VOR approach. The crew was responsible for this portion and the controller should be monitoring the progress and altitude, that didn't happen. A terribly dangerous clearance that still baffles me, and then backed up with the statement, "I gave 7800' or above"? Did ATC really mean that? has he given this clearance before? will he do it again? not likely. The crew lived to learn a valuable lesson the hard way and we have the comfort of debating their lesson on the keyboard with the hindsight being 20/20. I'm sure that part of their acceptance of this clearance was the preconditioning from being assigned altitudes below published when being vectored to final. As we all now this happens on a regular basis. No excuse, just trying to understand how one gets there. |
Originally Posted by galaxy flyer
(Post 2516787)
Dead men walking.....
GF |
Originally Posted by CBreezy
(Post 2520276)
You're right. We should refuse clearances that descend below platform altitudes.
The controller has NO business including the MVA in that clearance, however, as it serves NO purpose in that application, and it dangles a very dangerous carrot. It so happens in this case that the crew tried to take a bite. |
Originally Posted by JohnBurke
(Post 2521593)
No, we shouldn't, as MVA is a useful altitude with a purpose. A vector, however, which is the function of the MVA, presupposes that the controller is taking responsibility for terrain clearance and traffic separation. When assigned to an approach segment, in which the pilot ultimately has responsibility, the pilot should determine the altitude to fly...especially an "at or above" clearance.
The controller has NO business including the MVA in that clearance, however, as it serves NO purpose in that application, and it dangles a very dangerous carrot. It so happens in this case that the crew tried to take a bite. |
Originally Posted by galaxy flyer
(Post 2514943)
FAA ATC is required to assign an altitude with the approach clearance when clearing an aircraft on an unpublished route. See FAAO 7110.65 4-8-1 Approach Clearances. This was very technically legal as the MVA was 7,800 from where the aircraft was located to CEGAN...
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). http://i66.tinypic.com/zmdw28.jpg 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. |
Originally Posted by CBreezy
(Post 2522406)
It was sarcasm. GF was insinuating that anyone accepting a clearance below the platform altitude of an approach is a "dead man walking."
GF |
ATCBob,
No argument with your ATC experience, I was referencing 4-8-1 Note 1, which says, The altitude assigned must assure IFR obstruction clearance from the point at which the approach clearance is issued until established on a segment of a published route or instrument approach procedure. GF |
Really dude?:eek:
|
Originally Posted by galaxy flyer
(Post 2522864)
Do it often enough and you could be the SKW crew. Do it in the days before EGPWS and the outcome won’t be good. I’d be real careful about accepting altitudes below “platform” which is the intermediate segment. There’s only 1,000’ ROC on the intermediate segment, potentially not much clearance. I never did unless I knew exactly where the terrain was; no harm staying a couple hundred feet high.
GF |
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