1wife2airlines

A quick glance at the chart shows about a 20 mile arc and a 20 mile final. Why would they want to get down and close to the terrain and get bounced around when not necessary if they had any vertical navigation awareness? The FMC might also have given them some vertical navigation info if time permitted finger fking it.

rickair7777

They're used to getting slam dunked in places like that, so they're spring-loaded to get down sooner rather than later, especially on a complicated approach.

Worth noting that a SLC 900 probably had a very, very senior CA (who grew doing a VOR approaches into mountain holes in a metro), so there's likely some cultural misunderstanding about how those at-or-above clearances work.

rickair7777

I agree. Confusing at best, if not an outright bogus clearance.

SKW CRJ's don't do coupled VOR approaches with the FMS. They could, and likely would, use the FMS for the ARC, but would need to switch to raw data before the marker. They still typically would have displayed the FMS course w/ constraints on the MFD.

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.

PerfInit

Lots of valuable lessons here. Pilots Must query ATC if a clearance does not make sense or is unclear.

1wife2airlines

250Kts and 10000' at Cegan would be my off the cuff planning depending on the type of course. In areas of terrain I would rather be high and adjust. Why drive around at 7800' 40 miles out? A 27 mile arc to final would not be complicated even with just a bearing pointer.

JohnBurke

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.

Hetman

http://libraryonline.erau.edu/online...s/AAR75-16.pdf

badflaps

I was going into JFK that day, never seen worse low level turbulence. Had the F/O call airspeed on final, as the panel was unreadable. One of those days you earn it for the year. We got to the gate, passengers had to jump to the jetway. Outbound Capt. gave me a dirty look. (JFK-BDL)

HIFLYR

ATC did not say descend and maintain 7800 ft until the fix just cleared the arc and cross xxx at or above 7800ft. One look at the chart shows the arc to be 10000 until intercept.

JohnBurke

Your sentence is not very clear, however, according to the article under discussion:

"A Skywest Canadair CRJ-900 on behalf of Delta Airlines, registration N162PQ performing flight OO-3567/DL-3567 from Salt Lake City,UT to Medford,OR (USA), was on approach to Medford's runway 32 cleared for the VOR/DME C via the arc approach with the additional instruction "cross CEGAN at or above 7800 feet". "

ATC cleared the flight to begin the arc "at or above 7,800." The arc begins at CEGAN.

The crew descended to the altitude in the clearance, which was the MVA, and had a GPWS terrain warning, to which they responded, hence the article.