cncpc wrote:I'm not sure where the story about 10 minutes later ever came from. It may be that it was ten minutes till the Borek crew saw the accident scene on the hilltop.
Charter flight #6560 en route to Resolute Bay from Yellowknife last reported communication at 12:40 local time, approximately five miles from Resolute Bay airport. The Boeing 737-200 with registration CGNWN went down at approximately 12:50 local time.
The CADOR says the occurence time was 1740Z. Some misunderstanding at First Air, I guess. The last communication was supposedly three back.
The Cador says this is the weather...
Weather was reported to be a 200 foot ceiling with 3 miles visibility in fog and drizzle; wind was 180 degrees at 10 knots.
That casts a different light. The ILS is barely makeable. The localizer 35 is about 150' below minimums. It doesn't say whether the ceiling was broken or overcast.
Definitely not the weather to circle, or to try a 540 minimum localizer if the glideslope seems to not be working.
They would have been able to see the hill from the ground at the airport, but not the top 150 feet.
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Good judgment comes from experience. Experience often comes from bad judgment.
There seems to be discussion on the ILS Inbound track versus the VOR inbound track. Possibly you should address the "Instrument Transfer Switch" system, if this 737 was so equipped.
The two female survivors reported the impact came completely unexpected with no obvious problem prior to impact. The girl received a leg fracture and was found sitting on a rock in tears by the 23 year old female, who also managed to get away from the wreckage, and taken to a safe place. Investigators could not yet speak to the male survivor due to health condition.
NAV Canada reported the aircraft was on an ILS/DME approach to runway 35T when it collided with terrain east of the runway at N74.71883 W94.91867. 4 crew and 8 passengers perished, 3 passengers received non-life threatening injuries. Weather was reported: 200 feet cloud ceiling, 3 miles visibility with fog and drizzle, wind from 180 degrees at 10 knots.avherald
hartley wrote:There seems to be discussion on the ILS Inbound track versus the VOR inbound track. Possibly you should address the "Instrument Transfer Switch" system, if this 737 was so equipped.
hartley wrote:There seems to be discussion on the ILS Inbound track versus the VOR inbound track. Possibly you should address the "Instrument Transfer Switch" system, if this 737 was so equipped.
The big Gotcha with SP-177 equipped 737-200Advs and non-EFIS Classics were the HSI source selectors, sometimes referred to as “Killer Switches”. These were located either side of the MCP and changed the HSI to show deviation either from the LNAV or ILS/VOR track. It is vitally important that these switches are set to VOR/ILS before commencing an approach otherwise you will still be indicating LNAV deviation rather than LLZ deviation.
If either Nav receiver fails, the VHF NAV transfer switch may be used to display the functioning Nav information onto both EFIS and RDMI’s. With Nav transferred, the MCP course selector on the serviceable side becomes the master, but all other EFIS selections remain independent.
If an IRS fails, the IRS transfer switch is used to switch all associated systems to the functioning IRS
Wouldn't that switch be in the same position to navigate off of either the ILS/LOC or the VOR? The other selection being for GPS nav? And then wouldnt it come down to switching the frequencies from the VOR to the LOC at the beginning of the approach?
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The only three things a wingman should ever say: 1. "Two's up" 2. "You're on fire" 3. "I'll take the fat one"
We have one -200 with the SP-177 and it has a full MCP with an "LNAV" button. There is no switch to change over. When you want to do a VOR/LOC or ILS approach you hit the "VOR/LOC" and "APP" buttons as you would in a Classic or NG. I don't believe First Air has any SP-177 equipped machines.
In our SP-77 equipped -200s there is a push button, "FMS"/"VHF" or "FMS"/"VOR/LOC" and a few have another "LNAV" push button, depending on the airplane and FMS installed. This is for flight director and autopilot coupling. It is used to switch between GPS nav and VHF nav and I'm sure First Air's aircraft would have something similar.
The instrument transfer switches are redundancy switches and are used in case of failure of a VG, DG, or VHF nav on either the Capt. or F/O side.
So the $64K question: is there any plausible scenario (with either the SP-77 or SP-177 AFCS) where the HSI would indicate the deviation from the VOR track instead of the localizer while they were showing a good GP indication?
With the SP-77, while in VHF nav mode, the only time there would be G/S indication would be with a valid ILS tuned up and the mode switch in "VHF" or "VOR/LOC", depending on the installation.
When in FMS mode, if First Air has an FMS system with pseudo G/S capability for RNAV approaches, as we do, the G/S is not available for RNAV approaches using ILS or LOC/BC RNAV waypoints. It is only available on non-precision RNAV approaches and WAAS approaches.
In my previous capacity with the Regulator and the Service Provider, I had a few discussions with the TSB folks, even gave them (at their request) an interpretation on TP-308 criteria for investigation proposes. TSB indicated several times (to me) if reliable data is available in the initial stage Field Phase, they can determine within a few days the direction the investigation is going to take. I’ll bet they have a very good idea now but the biggest stage is” why”……..
The TSB says they were doing a ILS/DME 35T approach. Even if there was a switch that could have caused them to track the VOR, they would have done a missed approach when they reached 397' on the glideslope. That would have occurred farther back over flat ground.
The survivors say it was a normal approach until they hit, so there was no missed approach.
That tells me they were NOT using the glideslope at all.
I used to fly for Bradley in 1976-77 in resolute on DC3 and twin otter.The first thing I noticed about those hills to the east was the aircraft wreckage.I am sure I counted 3 or 4 crashed airplanes.It was a challenge to get in and out of resolute with the fog,snow low vis or 0-0 weather that only occurred over the airport.Sometimes we had to land on the road down by the village in the twin otter and taxi up to the airport.I am sure everyone will look forward to the complete results of the TSB investigation.In the mean time I look forward to all the possible scenarios posted by all you professional pilots and crew as information is knowledge and we just want to prevent accidents in the future. Fly Safe
What other approaches are there for 35T (besides the ILS/DME)? I don't have YRB plates. The TSB website states they were on approach to 35T...where does it say they were doing the ILS/DME? Anyone have a link to that info?
Even if there was a switch that could have caused them to track the VOR, they would have done a missed approach when they reached 397' on the glideslope. That would have occurred farther back over flat ground.
No, that would not have been the case in the mistaken VOR scenario/speculation. They would have had an indication that the GS was U/S; therefore they would have continued on what they would have believed to be the LOC 350T approach and would have continued to 540'. The missed approach point is 0.2DME from IRB, but their DME would heve been the VOR and they would have hit the hills almost precisely where they did.
Nothing I have read here contradicts the VOR scenario/speculation; however, that does not at all mean that this is what happened.