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Continental TurboProp crash inbound for Buffalo

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Continental TurboProp crash inbound for Buffalo

Old 15th Feb 2009, 21:17
  #341 (permalink)  
 
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Student: read previous posts in the thread and you'll get all the explanation you want.

Autopilots generally control pitch using elevator trim, and can "disguise" a serious out-of-balance situation that's developing due to icing by just dialing the trim slowly out to the stops...

Which can lead to a very nasty surprise for the pilot when the AP is turned off for landing - in the case of a long-lever-arm plane like the Q400 perhaps a ton of trim force trying to point the nose or tail at the ground (depending on where the ice is)

Kind of like your instructor tossing overboard a box of cement blocks tied to the tail or nose at 1600' - and then saying "Your airplane!"

Flying manually, the pilot will notice "Man, this thing is getting really nose/tail-heavy" through his/her fingertips long before the plane becomes fully uncontrollable, and do something about the situation more creative than the AP's trim-only solution.

I should add in light of the following posts that:

the NTSB makes RECOMMENDATIONS
the FAA make RULES and LAW
the airline sets and enforces company POLICIES & PROCEDURES
the manufacturer recommends procedures

It is probably a very good idea to fly manually in icing - but the law doesn't always require it. And even the NTSB seems to be backing away from putting too much blame on using th AP - yet. As would I.

Last edited by pattern_is_full; 15th Feb 2009 at 21:43.
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Old 15th Feb 2009, 21:20
  #342 (permalink)  
 
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NTSB update

captain had been NEW to plane, getting IOE just 3 months ago. copilot had 700 hours in type.

delay out of newark due to high winds, up to 57 mph.

light to moderate icing in BUF area.

DEICE turned on 11 minutes after takeoff from NEWARK for entire flight!!!!!

flaps to 10 upset 26 seconds prior to crash

20 seconds prior to crash, FULL POWER selected

first motion during upset was pitch up to 31 degrees!!!!!!!

45 degree nose low

rolling left 46 degrees

rolled right 105 degrees!!!!!!!!!

G forces .75 to 2 gs

900 feet MSL, 650' elevation at crash site... last plot at 900 feet heading was 053degrees, right roll 26 degrees 30 degrees nose down air speed 100 knots!

1800 feet msl to 1000 feet took five seconds...4800 fpm?

I think it entered a partial spin.

anyone know what VREF would have been?????

all six blades of number two found

4 of number one found...burned,melted...composite blades. didn't seem to lose prop prior to impact.

autopilot useage...best to fly manually for feel of changes due to ice...ntsb

FAA says use autopilot in high workload areas. To say that you should be off autopilot is not what the FAA says. Big political head butting with NTSB and FAA

Flight manual says: disengage autopilot in severe icing conditions...nothing to determine icing was severe (see my previous post).

Trim motors not heard on the CVR.

and then FOX stopped carrying the briefing...cnn didn't even do it at all!!!!!!!!!!
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Old 15th Feb 2009, 21:23
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NTSB press briefing. 22:20 UTC 15 Feb.

Now pointing out that there has been no determination as whether this was "severe" icing and as such it is INCORRECT to say that the pilot was in violation of procedures. So far everything they have seen suggests light to moderate but it is still to be determined.

There is no AFM restriction on the use of the autopilot unless in "severe" icing.
The NTSB has a recommendation out regarding use of autopilots in icing however NTSB recommendations are not the law not do they form approved procedures.

I was getting peed off with today's media trashing of the reps of the pilots. Seems the NTSB have seen it too and have moved to quash it.

Last edited by Daysleeper; 16th Feb 2009 at 06:09. Reason: Edited to remove now complete webcast link.
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Old 15th Feb 2009, 21:23
  #344 (permalink)  
 
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cnn didn't even do it at all!!!!!!!!
I'm still watching it on CNN.com Live right now, Captain Steve is doing a terrific job of explaining the latest findings to the press.
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Old 15th Feb 2009, 21:26
  #345 (permalink)  
 
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1800 feet msl to 1000 feet took five seconds...4800 fpm?
My post-beer math is a little rusty, but don't you mean 9600fpm?


Also, as someone posted a few pages back (and I can't find now) the briefing is available here:
wgrz.com | Buffalo, NY | Home
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Old 15th Feb 2009, 21:27
  #346 (permalink)  
 
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Jackdaw

I agree that the reason it was given a common type rating was to save money. In fact im suprised it was given one at all, its a completly different beast to the classics.

However as I said before I have not seen a report which says the boots on a Q400 are unsafe have you?


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Old 15th Feb 2009, 21:27
  #347 (permalink)  
 
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PTH said everything in my notes from the briefing.

Did they say WHEN (in the sequence of events) the autopilot disconnected?
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Old 15th Feb 2009, 21:27
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NTSB briefing

speed right prior to flaps and gear was 134 knots calibrated
descent from 1800 to 1000 ft was 9600 ft/min
autopilot disengaged when stick shaker activated
no indications so far that there was severe icing Pireps or other info
icing switch (+20 knots) was engaged
flaps never got to 15 degrees. At 10 degrees they were retracted together with the gear
pitch was 30 degrees nose down, speed was then 100 knots aprox
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Old 15th Feb 2009, 21:30
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AFAIK "underpowered" and "not producing enough bleed air for thermal de-icing" are not synonyms.

Perhaps you can get out enough hot air from PW150 to de-ice wings (provided bleed-air installation is scaled up) and stabilizers but what will be left to push the aeroplane forward? It will still fly but performance penalties might drastically reduce payload and make your prospective customers turn to PW127 powered, boot equipped alternative.
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Old 15th Feb 2009, 21:31
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Assuming the stick shaker started AFTER the upset (disconnecting the autopilot), and the flaps traverse to 10 degrees triggered the upset, did the autopilot cause the first pitch up to 31 degrees (before the stick shaker disconnected it)?
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Old 15th Feb 2009, 21:35
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A 31 degree pitch-up after flap transit to 15, seems to make tailplane stall less likely. That kinda motion almost guarantees a clean stabilizer.
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Old 15th Feb 2009, 21:39
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MD80F, yes. At first blush, there appears to be plenty of pitch and roll authority.
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Old 15th Feb 2009, 21:42
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9600 fpm , yes...sorry and thanks bubba
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Old 15th Feb 2009, 21:46
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what is Vref for this plane...assume max landing wt. ????

what is normal stalling speed for clean (VS1)

stall speed VSo?

wondering.

j
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Old 15th Feb 2009, 21:50
  #355 (permalink)  
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It depends if you are landing F15 or F35 and of course dependant on weight.

But somewhere inbetween 95kts (very light) to 120kts or so. This is from memory so may not be wholly accurate.

Can't remember stall speeds but 1/1.23 multiplied by the above speeds would give you a rough figure.
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Old 15th Feb 2009, 21:50
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One comment the NTSB fellow made during the Q&A hasn't been mentioned here. He stated that from the flight data it did not appear that the trim motors were doing anything excessive (or words to that effect) while the autopilot was on. He was apparently saying that the autopilot does not appear to have been "hiding" a severely out of trim aircraft.
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Old 15th Feb 2009, 21:51
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Those slagging the aircraft for being purchased due to being "cheap". Well, duh! Of course it's purchased because it's cheap. The bloody A380 is purchased because, all things considered, someone has decided it is more economic to operate over the sectors it flies on than its competitor's aircraft, in other words it is "cheaper". Just because something is chosen for economic reasons doesn't mean it is unsafe, if it also turns out to be unsafe, then sure, ground the things, but until that's been decided some of the comments here are a bit rich.
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Old 15th Feb 2009, 21:54
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Well said AerocatS2A
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Old 15th Feb 2009, 21:55
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Va = 1,23 Vs
Va clean @ 44000 lbs : 130 Kts
Va clean @ 64000 lbs : 157 Kts

Va clean @ 54000 lbs (near actual landing weight) : 143 Kts

For Icing conditions add 20 Kts, hence min clean speed was about 163 Kts.

Post # 361 states speed prior selecting gear and flaps was 134 Kts...
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Old 15th Feb 2009, 21:57
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Is there moisture in the plumbing of the inflatable membrane? Plain and simple question put to ya.
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