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"identified, Radar contact" |
BOAC
Admit, to mention these words might be somewhat misleading. The assumption that they were flying on just flight plan data and reporting to ANC ATCC via a radio relay station might be correct. The opposite might be correct as well and via some detached RADAR station ANC can see them on RADAR ??? But the question still is unanswered: Based on which factual information the clearance for a direct course to a RNAV position connected with an instruction " to maintain at or above 2000ft" was transmitted to the crew ??
My basic assumption in this case is to believe that all of the person involved in this accident knew all about the weather conditions and the terrain situation much better than one at hindsight can determine. |
Yes. Barring some unknown unfortunate problem occurring, we appear to be in the 'old fashioned aviation' arena here:-
1) Know where you are 2) Know where to want to go 3) Know how to get there |
Yes, fully agree!!
Interesting reader comments under that Aviation Herald report! |
Well, it's either me or them, but why are people on AvH saying 'they should have requested to climb to 4300' when they were cleared NOT BELOW 2000' ?? Is it me or these posters not understanding the clearance?
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Probably the understanding of clearances on this side of the pond differs ??
As I see it, this clearance covered any level between 2000ft. and as high as they could fly. That is one of the reasons that make me shrug, a good clearance should not leave any space for individual interpretation. Great guess, it must have to do with the special conditions in Arctic Flying. |
Hopefully the answer to why they held at ZEDAG below 4300' will come from the CVR.
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BOAC:
Hopefully the answer to why they held at ZEDAG below 4300' will come from the CVR. The FAA and NTSB already have the answer to the question, "Why were they cleared at or above 2,000, and how high did the 'above 2,000' go?" |
Looking at the Alaskan VFR chart ( the only one I have ) the MSA from the East ( coming from ANC ) is 2.800 Ft. After passing the Chigmit Mountains the terrain is pretty flat until DLG, the highest obstacle in that peak at 2550ft near the IAF. ( Ironically a direct track ANC-DLG would keep you well clear of that Peak.)
Surely the guys had also a GPS moving map with terrain on it, and warnings probably. Must be something else... |
Copy all that aterp, but the question remains
why they held at ZEDAG below 4300' Are you now saying they WERE probably radar identified? and on the route they were flying are typically radar identified.:confused: |
BOAC:
The area along their route has radar coverage. They went off frequency to obtain a runway conditions report. So, if or when the ARTCC's EMASW went off ATC couldn't contact them in the brief time before impact. The remainder of your questions will have to await release of the radar, ATC communications and (hopefully) the CVR data. |
Someone on another board plotted their probable route of flight on SkyVector.com:
SkyVector: Flight Planning / Aeronautical Charts |
I am not aware of the different levels of ATC service in those parts, but have we established what they were on, or perhaps thought they were on?
Also why BOTH off frequency? Single radio? |
OK465:
Apart from altitude issues.... I would guess that for RNAV equipment, a 'vintage' Be1900 would probably be equipped with a G530 or even 430, a fairly basic display of the profile, IIRC without displayed altitude constraint info. In addition, when holding using this type of system, the steering guidance for NAV goes into a 'suspend' mode at the intended holding fix, requiring use of a HEADING SELECT type mode for the outbound leg of the holding pattern AND the turn inbound. So you're not really on a structured RNAV routing at this point. This is holding 101. This requirement coupled with the existing 17 knots or more of right cross outbound at holding speeds probably ~150 certainly makes precision tracking as well as positional awareness challenging. Same for a 400W/500W although they supposedly get course guidance the first time around. In any case the evaluated and protected airspace for this hold is huge, because it was evaluated for climb-in-hold (310 KIAS) for the missed approach for the RNAV Rwy 1. The terrain they hit is well within the 200 KIAS primary holding area. |
okc465:
This is reminiscent of the old 'cruise' clearances, i.e. "cruise 2000, cleared for an approach". Pilot adjusts as required, phone call on the ground.... Is that in play at PADL? |
What are the odds that a B1900 in cargo configuration (< 6 passenger seats) had a CVR? FAR 135.151 indicates one would not be required.
ACE flies a "combi" B1900 with passenger seating as well as 4 cargo planes - but it's not the accident aircraft. |
BOAC:
Also why BOTH off frequency? Single radio? |
aterpster
I checked in FlightAware for a track of the flight and found this:Alaska Central Express (KO) #51
Iīd like to say now there is even more than a mystery why they had to hit that mountain. The Speed / Altitude graph clearly shows they were at a safe altitude until few minutes before the crash. As well, aside of all RNAV related questions it appears they initially where flying on an airway, most probably established on a radial of AKN VOR and having DLG ahead of them. Plus the RADAR coverage. Big, big question WHY !!! |
If those speeds are reliable, they are fast for a hold and the rate of descent is high.
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BOAC
Looks like they had a good tailwind>> check weather in AvH report!
Could that fairly steep descend indicate some ice problems ? Donīt know how good the ice provisions are on a Be 1900?? Was mentioned before by other poster, but to place that holding pattern to the side of the highest mountains and a non standard right hand pattern is something to wonder about at least. |
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