737 reported down in Canada

[PLovett]

the a/c may have been chasing a false localizer course

RESA, not saying you are wrong but another aircraft flew the backcourse approach twice, the second time becoming visual without reporting any anomalies.

[Rockhound]

Aterpster,
Thanks, I did see that photo shortly after I put up my last post. It's the most instructive I've seen of the crash site.
Looking at the wreckage, I am amazed that anyone survived. Most probably they did so because they were seated in the very tail. That's where they put the pax on largely-freight flights to YRB (that's what the majority of the flights are anyway). The degree of fragmentation of the aircraft is remarkable. Maybe that's what Rollingthunder means when he says that the wreckage doesn't look right.
One thing's for sure, you don't want to find yourself at low altitude east of the YRB runway unless you're in a helicopter in CAVU conditions.

[RESA]

CYRB First Air 737 crash

PLovett

CYRB back course is 17T . . . no GP

Approach is 35T with GP(glidepath)/DME.

Technically, the only correct way he could report 3 N.M. to threshold is on the 35T approach.

[Capn Bloggs]

Originally Posted by Rockhound

I still find the suggestion that he was circling to land on Rwy 17 difficult to accept. A tailwind of 10-15 knots straight down the runway should present no difficulties for a 737.

A sub-2000m gravel runway in poor weather with up to 13kts of downwind in a 737-200, which most probably has a Flight Manual 10kt tailwind limit (as other early model 737s). I would not class that as a "no difficulties" approach.

Also interesting was the presence of the other aircraft. While the timings are not clear, if an aircraft had gone missing, I would have thought it prudent to hold somewhere out of the way until the whereabouts of the missing aircraft had been resolved. It might have had a radio failure and be attempting further approaches. It would certainly load me up knowing there was another aircraft doing instrument approaches in the opposite direction to mine.

[JammedStab]

Originally Posted by RESA

I am concerned that, given the perceived impact location and track of the debris field, the a/c may have been chasing a false localizer course. The location’s offset from the localizer’s centreline (localizer being a couple of thousand feet past the stop-end in this case) suggests a possible false course. This ILS is thirty years old plus (and a second hand installation . . . used elsewhere before Resolute). ICAO deemed this ILS model unacceptable . . . no longer to be installed as of about the end of the 1990’s. This model has had a know history of false courses.

The installation is somewhat “unique” and apparently required some optimisations given the immediate airport terrain. On a false LOC course . . . the GP course (rate of descent) may not look that unreasonable. The locator NDB (2.1 N.M. before threshold on extended centreline) was decommissioned last summer . . . so you no longer have that reference to tell you it’s on your port/starboard/or behind you when the DME is counting you down to threshold.

Have heard of false captures but not a false localizer.

http://www.pprune.org/rumours-news/4...ml#post6654152


Looking at top post in the above link,


I can guarantee that it is standard procedure for a crash investigator to check the position of all instruments, knobs, handles, etc in the cockpit. This includes the nav frequencies selected.

[RESA]

CYRB First Air 737 crash

Transportation Safety Board of Canada - Welcome

Transportation Safety Board of Canada - Featured Investigations - Aviation - 2011 - A11H0002

[PLovett]

RESA, I understand that there is no GP on a backcourse approach but it was the localiser signal that you referred to in your post as being possibly at fault. That is the same signal either for localiser or backcourse.

[RESA]

PLovett

BC 17T has an NDB (YRB) 1.5 N.M. before threshold on centreline.

Sation passage at YRB should put you inside +/- 20-degrees of centreline, so any LOC lock should be very near centreline and not a false capture or false course. If your LF DF doesn't spin before you are a mile from the runway . . . you are likely not heading for the runway centreline . . . ?

The prop jockey landing on 17T had this advantage (albeit with no GP) . . . likely more "aware" because of no GP?

[RESA]

JammedStab

Older Localizers (certain brands) frequently have false capture problems . . . particularly on very long runways as the equipment is being overdriven in order to narrow the course width.

Some older equipment (still in use) employ an antenna system that can partially fail causing both false capture and false course that the executive monitors will not detect.

nuff said . . . not about to give course here . . .

[Sonny Hammond]

Is it possible they still had 29.92 set as opposed to local qnh?

[mauswara]

B732 max tail wind limit 15 kts(AFM:Tkof/Ldg) .Can't find a reference to gravel ops that reduces it.Nicest aeroplane I've ever flown,by far.

[remoak]

I might be way off base but something about the wreckage does not look right.

How can the wreckage "not look right"? Are you suggesting that somebody has been out there moving things around? If not, what ARE you suggesting exactly? (not having a go, genuinely interested in what you are thinking)

[Mad As A Mad Thing]

Looking at the maps that have been put up showing the crash site it strikes me that the aircraft's track to the VOR indicated on The map looks very very close to the ILS course.

Is it possible that they had mistakenly selected the VOR frequency rather than the ILS and flew what they thought was the localiser course straight towards the VOR with it's unexpected high ground in the way?

Pure speculation from a non-pilot so feel free to explain why this would or would not be possible.

[BOAC]

Probably because I cannot find a VOR there?

"B732 max tail wind limit 15 kts" 10kts is a standard unless negotiated with Boeng (ie pay more money)

[opale4]

There is no VOR approach, but there is a VOR in the vicinity of the impact location.

[Rockhound]

Capn Bloggs and BOAC,
Pilots flying in the Canadian Arctic of necessity tend to push the envelope routinely, but have the experience to do so in a professional and safe manner. Their excellent safety record, in a challenging environment, speaks for itself.
Rockhound

[BOAC]

Originally Posted by opale4

There is no VOR approach, but there is a VOR in the vicinity of the impact location

- tell us more. Jepp do not know of it.

Rock - not QUITE sure why I was addressed in that post, and I see no justification in 'pushing any envelopes' when you may kill yourself and your pax/crew?

Forgetting all about tailwinds, back-courses, front courses, circling etc:

1) The impact was too close in for a 'downwind' (yes, even in TERPS)

2) IF major technical failure is ruled out, what does that leave you with - 'envelope pushing'?

[opale4]

Originally Posted by BOAC

- tell us more. Jepp do not know of it.

I don't have access to Jepps right now, but the link below shows the location of the VOR.

http://www.ourairports.com/navaids/YRB/Resolute_Bay_VOR-DME_CA/

[Zeffy]

Thanks, opale4.

Because the YRB VOR DME wasn't relevant to the ILS 35T approach, it does not appear on the AIP or Jeppesen chart. The VOR DME is depicted on the enroute chart.

Check out this report of a GIII accident at KHOU in 2004.

[westhawk]

Originally Posted by Zeffy

Check out this report of a GIII accident at KHOU in 2004.

I remember following that one. A very early start, a rushed approach and tracking the VOR instead of the LOC. Confusion about the EFIS presentation of fast/slow and G/s indications. They were supposed to be picking up George H.W. Bush. Two highly experienced pilots made a mistake that's not all that difficult to make.