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Author Topic: TBM-700 N731CA crash outside of MMU  (Read 33724 times)
dylanh
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« Reply #15 on: December 21, 2011, 09:54:47 PM »

The remarkable thing is how little time transpired between entering IMC and loss of control…4 to 5 minutes max?  Wow!  A little frightening to think that, even at gross weight, an aircraft of this stature could encounter so much ice that it becomes unflyable in such a short period of time. Flightaware provides the data:
http://flightaware.com/live/flight/N731CA/history/20111220/1400Z/KTEB/KPDK/tracklog     
Between 13,900 (start of IMC?) and 17,400 the airspeed and rate of climb falls off pretty quickly.  Unless there was a reduction in power, these data seem consistent with increasing drag associated with ice. The idiosyncrasies of the deicing boot cycles on the TBM700 mentioned by Wilky10 are noteworthy.
I think the strategy and mindset of how you approach the ice is critical.  Do you assume you won’t have a problem and plan to react if you do?  Or do you assume you will have a problem and don’t react if the problem doesn’t materialize?  There is a critical distinction between these two mindsets.  One puts you ahead of the plane the other can put you behind the airplane at a time where behind is really bad.
An example….do you fly an ILS with the mindset of “I am going to miss “or I am going to get in?  I used to assume the latter.  I hadn’t missed an actual approach in years…why would this time be any different?   So flying a ILS into IND I had it LOCKED into my mind that I was getting in.  Yeah, I briefed the missed approach instructions but my MIND had no intention of missing.  Well turns out there was no runway environment in sight at the DH.  My first reaction was WTF?  The second was to be somewhat insulted (silly as it sounds) and my third reaction was to pitch up, power up at which point I looked down to see what the missed instructions really said.  It was a disorienting experience trying to make a full power climbing turn while rereading the instructions I has read less than 5 minutes prior.  I didn’t catch up to the aircraft until I was finally reestablished on the ILS.  Beat myself up pretty bad over that experience and never forgot it.  Every approach I make today I plan on missing.  If I break out prior to the MAP/DH I take it as a positive “surprise”.
Judging by his words to the controller the pilot of 700CA certainly didn’t anticipate a problem.  He even used the words “it will be no problem for us”.  And why would it be?  Probably seen ice dozens of times and it was never a problem.  So the transition from “it won’t be a problem” to “holy crap I am in serious trouble” took less than 5 minutes.  Could you get your head wrapped around that swing in reality in a seamless fashion?   Would you have the discipline to recognize how bad it would become so quickly and initiate an emergency descent in NY airspace without hesitation?  Seems like a pretty tall order.  If you agree, plan for an escape no more than 60 seconds after entering IMC when moderate to severe is reported.  If you get surprised because it is manageable….it will be a surprise you can live with. 
It may turn out that that ice had nothing to do with this tragic event or that there were other factors like an out of envelope or overweight aircraft or a systems failure.  Regardless, assuming the worst vs. expecting the best is worth considering.

^^^^^ Quite possibly the best story/reply/advice I've read online. 

The "beat myself up pretty bad" hits home. The road to where we are at in our professional pilot/controller careers is littered with these moments.  (lord knows I've had my share). The feeling of invincibility comes from doing the same thing over and over and not getting bit.
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Flyboy77
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« Reply #16 on: December 21, 2011, 11:03:22 PM »

Remember, boots are not foolproof. Icing can overwhelm the boots and create a 'cavern' effect, creating a void under the ice for the boot to expand with no effect on the ice buildup (not sure how to explain it a little clearer). With the reports of severe icing and airliners mentioning issues fending off the ice, I'm not sure the TBM with just boots could handle that type of encounter.

Ice Bridging does not exist in modern boots systems and they are not susceptible to run back according to the manufacturers.  However Ice accretion rates should be watched carefully.  When Airliners are calling sever ice you better avoid the area...
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SASD209
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« Reply #17 on: December 22, 2011, 12:55:05 AM »

Just an observation about the 2nd recording of the response...is it me or does it seem like the news choppers are like vultures descending on some prey? I understand the need for the press to get the story, it just seemed a bit unsettling knowing 5 people had just died and the news choppers are racing to get the first video of it. Oh well, YMMV. RIP to those lost.
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aviator_06
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« Reply #18 on: December 22, 2011, 08:16:28 AM »

Very sad to here. Thoughts and prayers with their families.
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Hollis
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« Reply #19 on: December 22, 2011, 09:15:31 AM »

Severe icing = rapid ice accretion, (less than 5 minutes) partial loss of lift, increased drag, causing entry into the back side of the power curve, loss of roll control and resultant stall-spin.
Been there, done that.
Recovery? Nose down (way, way down), throttle(s) back, controls neutral, then hopefully get to an OAT of 34F or higher and wait until the ice sheds enough to get full contol again.
 
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FR8K9
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« Reply #20 on: December 22, 2011, 03:16:58 PM »

I am not familiar with the TBM 700 but in addition to the icing issue another factor the NTSB is sure to consider is the loading of the aircraft.  With five passengers, a dog, luggage, possible Christmas presents and the fuel on board for the trip, the permissible weight and balance limitations may have been exceeded.
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notaperfectpilot
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« Reply #21 on: December 22, 2011, 04:24:34 PM »

I wonder if it was both? Being over weight and ice didn't help matters either.
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DrCox
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« Reply #22 on: December 22, 2011, 05:37:47 PM »

I am ATC and it still amazes me how many pilots listen to the weather warnings and still choose to fly into the affected area. We shake our heads when we see it. It happens so often. I dont understand it. When you fly there are risks. When you fly in IFR there are greater risks. When you put passengers on board wouldnt you want to reduce the risks as much as possible? And when the passengers are children or your family wouldnt you want to even further reduce the risks?

I was once working a student pilot on his check ride. They departed and immediately their radio went bad. Not totally unusable but still bad. I informed him. He chose to continue his flight. And of course they returned nordo a few hours later. We had to put military jets in holding to accommodate his nordo landing. When I spoke to him over the phone he said he knew the radio was bad but they decided to 'go ahead and risk it'.

Now isnt flying risky enough as it is? Why further compound that by flying in controlled airspace with a known bad radio? Especially when the option to return to the airport, spend another half hour preflighting another flight school aircraft and then go off on the flight as intended with less risks?  In addition to more risk for yourself you are putting nearby aircraft at risk too by flying in controlled airspace with no communication with the tower.

This is what we dont understand. If youre going to play russian roulette with yourself thats one thing. But dont do it with passengers or other nearby aircraft.

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N62LM
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« Reply #23 on: December 22, 2011, 08:45:32 PM »

Remember, boots are not foolproof. Icing can overwhelm the boots and create a 'cavern' effect, creating a void under the ice for the boot to expand with no effect on the ice buildup (not sure how to explain it a little clearer). With the reports of severe icing and airliners mentioning issues fending off the ice, I'm not sure the TBM with just boots could handle that type of encounter.

As a TBM pilot, I can tell you that this aircraft should have been able  handled it.  If I am not mistake here, they were talking about light to moderate icing conditions.   VampyreGTX your explanation is correct.  This will occur if the boots are activated too early.  We don't know when the Pilot decided to activate the deicing boots.  Never the less, he should have had his prop deice on and maintain a proper air speed (cockpit management) regardless of the ice. The climb is secondary.

The boots on a TBM work as follows, the inboard come on and cycle for 7 seconds, then the same with the outboard.  There is a 53 second or so delay before they are activated again.

Did the Pilot put the boots on too early..?  Was his climb too steep and the ice build up was so rapid..?  You gotta remember the TBM 700 is a very well built aircraft.  For the TBM to break up in flight, one would have to think the speed was in the range of 500+ mph.  That's just my two cents.

I would be hard press to see if there was something mechanically wrong with the aircraft.  


Prayer and thoughts to the families...
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tonyairplane
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« Reply #24 on: December 23, 2011, 12:09:38 PM »

The AD says to activate the boots right away.  Apparently other TBM-700s have lost control at the first sign of ice.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/f671d6221d402b6586256a4900563e19!OpenDocument&ExpandSection=-5
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FR8K9
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« Reply #25 on: December 23, 2011, 12:20:25 PM »

Here's a link to a good informative article on airframe icing that every pilot should review.

http://www.aopa.org/pilot/features/inflight9910.html
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gsaviator
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« Reply #26 on: December 23, 2011, 01:50:21 PM »

Ice Bridging does not exist in modern boots systems and they are not susceptible to run back according to the manufacturers.  However Ice accretion rates should be watched carefully.  When Airliners are calling sever ice you better avoid the area...

I can not speak for what the manufactures say about bridging, but I can certainly speak from my own personal experience. Ice bridging can and does occur on modern boot systems. I have seen it with my own eyes.
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N62LM
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« Reply #27 on: December 24, 2011, 10:09:10 AM »

The AD says to activate the boots right away.  Apparently other TBM-700s have lost control at the first sign of ice.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/f671d6221d402b6586256a4900563e19!OpenDocument&ExpandSection=-5


Not sure why the AD says that.  If you active them too early, then they are not effective at all and, when ice does start to build up during the dormant period of 53 seconds, then what..your basically f***ed..!  undecided
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tonyairplane
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« Reply #28 on: December 24, 2011, 10:52:36 AM »

My guess is that on this particular airfoil and configuration, the laminar boundary layer gets disturbed very easily, resulting in separated flow, and loss of lift and control.  So the system has to be used immediately, just as the AD says.  It says clearly that there have been incidents and an accident due to this.

Please don't take this personally, but you fly that aircraft and apparently weren't aware of this AD - I wonder if this guy was?
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gsaviator
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« Reply #29 on: December 24, 2011, 11:00:10 AM »

The AD says to activate the boots right away.  Apparently other TBM-700s have lost control at the first sign of ice.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/f671d6221d402b6586256a4900563e19!OpenDocument&ExpandSection=-5


Not sure why the AD says that.  If you active them too early, then they are not effective at all and, when ice does start to build up during the dormant period of 53 seconds, then what..your basically f***ed..!  undecided


Yep your 100% right. Use the boots too early and you are screwed. Unfortunately, Most aircraft manuals now tell you to activate the boots at the first sign of ice thanks to ADs that force a suppliment to the aircraft manual. This has always been the problem with having a bureaucratic sitting at a desk making decisions about something they know nothing about.

So look at the bright side. We must use the boots at the first sign of ice, Screw ourselves from being able to use the boots again on that flight, then build more ice and crash and not be violated for braking a reg since we did exectly what the AD said. Yeah, that sounds right. "FAA" always there to help.
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