Plane Crash in Alaska Cessna 208

[Cirrus N210MS]

http://r1.cygnuspub.com/files/cygnus/image/EMSR/2013/NOV/600x400/2e13fc9955139e28440f6a7067001432.jpg_11254095.jpg

http://www.emsworld.com/news/11254093/mother-on-crashed-plane-in-alaska-led-searchers-to-wreckage

[Brian_Gladden]

Part 121 or not. Caravan + Heavy Icing conditions = Should stay on the ground.... My condolences to those lost and injured.

[mfitch]

The purported weather in that article has not been confirmed. The crash occurred on the short leg from St Mary's to Mountain Village which is just a few minutes: they could see the destination and all the weather once off the runway. Freezing fog is not freezing rain. It is floating ice crystals pulled out of the ground by very dry air. It will leave deep hoar frost on anything still, but it cannot produce icing.

Villagers are nearly all related. A friend of mine originally from Mountain Village lost extended family and friends in that crash.

[Skyhawk_310R]

Part 121 or not. Caravan + Heavy Icing conditions = Should stay on the ground.... My condolences to those lost and injured.

What this man wrote!

Pilots need to understand that simply having de-ice or anti-ice on the plane does not mean continuing to fly in known icing conditions. Accumulation rates can exceed even the most sophisticated systems. The systems installed on GA aircraft are really designed to allow a pilot to get into icing conditions and stay safe long enough to immediately get out of it, normally by executing an immediate 180 degree turn and then once back in the clear, coordinating with ATC for a new destination or some feasible way to circumnavigate the icing areas. ATC will respond to a pilot declaring an emergency for icing conditions encountered and work with the pilot to quickly exit the conditions.

Ken

[Skyhawk_310R]

The purported weather in that article has not been confirmed. The crash occurred on the short leg from St Mary's to Mountain Village which is just a few minutes: they could see the destination and all the weather once off the runway. Freezing fog is not freezing rain. It is floating ice crystals pulled out of the ground by very dry air. It will leave deep hoar frost on anything still, but it cannot produce icing.

Villagers are nearly all related. A friend of mine originally from Mountain Village lost extended family and friends in that crash.

Yes and no. Technically, freezing fog should be small crystals, but often times the way supercooled water and pellets interact upon contact with the airframe can cause ice formations on the plane. This can be especially true in the engine, which can often become the most critical component to experience freezing.

Ken

[StormILM]

Reading this thread, I was reminded of an Aviation Safety Seminar I went to one year where we were given a talk about Icing Effects and I recall a tape being played of an MU-2 icing Emergency up in Canada. Here are the clips:

http://www.youtube.com/watch?v=Wbm8xzLVgQ4

http://www.youtube.com/watch?v=_lAu-HpzqM4

[Skyhawk_310R]

Indeed, and this month's AOPA Pilot magazine contains another documented case study of a recent mishap where a TBM-700 with FIKI equippment was flying on an IFR route at 14,000 feet and entered extremely heavy icing, what one veteran pilot told ATC was the worst accumulation rate he had experienced in over 34 years in his career! The TBM-700 pilot was either unaware of such PIREPS or ignored them. Either way, he decided against declaring the emergency and worked with ATC in a routine fashion before getting clearance to climb above the icing level, which was reported to be 16,000 feet, an altitude his airplane could easily reach in normal condition.

ATC radar indicated that the aircraft reached 16,400 feet and then entered a left spiral descent that manifested itself into a spin in IMC conditions that the pilot was unable to emerge from, resulting in crash with total fatalities!

The lesson AOPA rammed home, and I fully endorse, is for PIC's to stop being afraid or intimidated from declaring an emergency! Declaring the emergency is merely an internationally recognized tool for the pilot to invoke a requirement for priority of ATC services plus his right under ICAO treaty law to violate such normal rules as required to maintain flight safety for his aircraft, passengers, crew, and himself. Had this pilot simply declared that emergency, and informed ATC he was climbing immediately, ATC could have cleared conflicting traffic. As it was, ATC reported no nearby traffic anyway! Instead, the PIC spent critical minutes in the ice, accumulating weight and destroying lift on his wings. Even reaching above the icing at 16,000 feet a few minutes before he did (which he did but too late to maintain aircraft control above it), meant that he and his passengers would have likely survived! AOPA theorizes, and again I agree, that the pilot overestimated the true capabilities of his TBM-700's FIKI system, as well as grossly underestimated the risks.

I spend more time than I should with USAF student pilots trying to tear down their reluctance to declare an emergency, and trust me, when I have them in the simulator, I normally make them pay for that reluctance in a way that rams home the error of their reluctance! I'm a firm believer that a ton of sweat in a simulator can save an ounce of blood in the airplane! Somehow, someway, too many pilots (military and civilian) have this reluctance to declare an emergency even when ATC is literally asking them to! When ATC uses the phrase to a pilot, "Would you like to declare an emergency," that is ATC speak for, "Please declare the emergency and let me help you!"

Ken

[Skyhawk_310R]

Reading this thread, I was reminded of am Aviation Safety Seminar I went to one year where we were given a talk about Icing Effects and I recall a tape being played of an MU-2 icing Emergency up in Canada. Here are the clips:

http://www.youtube.com/watch?v=Wbm8xzLVgQ4

http://www.youtube.com/watch?v=_lAu-HpzqM4

Wow! I posted my previous comments BEFORE I listened to your two link clips! That's an amazing validation of declaring the emergency and working with ATC to salvage a bad situation and having it lead to survival where mishap and high risk of death would have likely been the case by hesitating to declare the emergency!

Yeah, they had God, good judgment, and quality ATC on their side that day!

Ken

[CG_1976]

I don't have enough info from the news clip at all to make any speculations or conclusions on cause. However Ice fog and diamond dust conditions in the Arctic US or Canada is h3ll on wheels. 1st thing to look at is the Crew and WX and overall experience in Arctic environment and climate. I can almost guarantee the NTSB are going to look at that.

[mfitch]

Yes and no. Technically, freezing fog should be small crystals, but often times the way supercooled water and pellets interact upon contact with the airframe can cause ice formations on the plane. This can be especially true in the engine, which can often become the most critical component to experience freezing.

Ken

How is the supercooled water produced? If moisture is sucked out of the ground, this is pulling from old snow and ice: nothing liquid even supercooled. Over water I could see supercooled water. Yes, St. Mary's to Mountain Village is along a river, so that is entirely possible in this case. Since taking an intro weather class, I have found learning about the details interesting especially as application of chemistry and physics.

[Skyhawk_310R]

How is the supercooled water produced? If moisture is sucked out of the ground, this is pulling from old snow and ice: nothing liquid even supercooled. Over water I could see supercooled water. Yes, St. Mary's to Mountain Village is along a river, so that is entirely possible in this case. Since taking an intro weather class, I have found learning about the details interesting especially as application of chemistry and physics.

You are discounting the effect that the temperature of the airframe can have, especially in light of variances of surface temperatures across the sections of the frame. Keep in mind the very delicate temperature situation in effect during such conditions. These crystals can hit a section of airframe slightly above freezing, melt immediately upon contact, roll aft quickly, and then refreeze.

This is similar, but not entirely the same, as the concept of supercooled water droplets. This is where due to lower atmospheric pressure, the freezing point of water can drop below 0C or 32F. Under such conditions, droplets can become large and this is the situation that causes clear ice, which is not only difficult to see, especially at night, but also becomes far more dangerous as the supercooled drops can hit the leading edges of aircraft surfaces, roll aft very quickly, and refreeze. The worst situations on the wings are for these drops (or crystals) to hit, roll aft, and freeze up aft of the leading edge de-ice boots or even leading edge de-ice heat. Same story for the more modern GA development of leading edge anti-ice sprays.

For the engine, as was illustrated in that chilling two-part video series linked on this thread, the engine can ingest ice, have it melt initially, but then roll back into the engine, quickly refreeze, and start playing pure havoc with cooling airflow. I know, cooling airflow in icing conditions! But, yes, surface ice can block air intakes, air filters, and end up causing the engines to overheat. Further, in older carb engines, the ice can form in the venturi float carb and that interfers or even disrupts fuel flows and can fuel starve a piston engine. For a jet or turboprop engine, the compressor vanes can have ice form in the same way on the vanes, and since vanes work like wings to use pressure differentials to accelerate airflow through the engine, ice can disrupt this airflow and lead to sudden compressor stalls or even to flameouts such as happened on that MU-2.

Such devices as engine ignitors can help alleviate or delay the ability of the ice to cause compressor stalls and flameouts, but in heavy ice accumulations, can often fail to prevent it.

I remember how FS had some "weather themes" where it claimed that there was this beautiful snowfall that still allowed for "great" VFR flying conditions! OK, fantasy time in a PC game is OK. But, that's not the reality. Whether freezing fog, ice pellets, or snow, never underestimate the chance of what is currently frozen precipitation in any form to go from solid to liquid to solid quick enough to cause very severe consequences inflight! This is also why the FAA has significantly tightened up the rulings for operations in forecast or known icing, including previous edicts to not merely "polish" off frost, but ensure its complete removal.

Ken

[StormILM]

I will add this, the below link is a brief accident summary that took the life of a family member of mine. My Uncle who was PIC of the Beech V35 Bonanza involved in this accident was a highly experienced Pilot, a WW2 Naval Aviator who saw action in the Pacific Flying both F6F and F4U Fighters. But according to some of my relatives including his late widow, he took too many chances with weather and managed to come through in every case except the last one. I was told that perhaps because of his skill & experience as a Naval Aviator that he took such chances. When I began to train to fly, my Aunt was terribly unhappy when I told her the news and showed her my Pilot Medical/Training Certificate but she simply told me to be careful and not take chances. Word spread in the family that I was now flying and not long after, I got a call from my cousin who's a retired USAF Colonel & F-4 Driver and it didn't take long for him to give me his safety lecture. At the end of that talk he said these words which I still hold with great value: "Our late Uncle took one too many chances and he paid for it. I don't want you to make the same mistake! Take my words seriously and just remember, when in doubt, DON'T"......

http://aviation-safety.net/wikibase/wiki.php?id=4439