Aircraft down in Montana?
Is there any way to find out whether this flight was operating under part 91 or part 135?
"For an accident to take place at the end of a flight, in general, would seem to be indicative that the plane was not over gross and the weight and center of gravity were within tolerances," he said"
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That seems a very strange claim to make.
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These NTSB folks dont seem to be all that savvy about aircraft.
Not that that is completely reassuring either.
Although it would be rare indeed for an aircraft to weigh more when landing than on takeoff But newsmedia are known to make mistakes when reporting on aviation accidents. Fortunately, pilots don't seem to make quite as many mistakes when flying.
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Weight and Balance seem OK, Icing very likely
I did weight and balance calculations using Pilatus own digital AFM. Weight and Balance were not issues. There were seven children on board of ages 2,3,4,4,5,7,9. There were four adult men and three adult women on board. Photos in the paper show them to be of normal size and weight. I assumed 960 lbs of baggage and 300 gallons of a possible 400 gallons of fuel.
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Icing most likely cause
A post above showed the track of the plane diverting left to Butte to skirt radar images of weather cells.
Also, Accuweather.com said that the plane passed through a layer of air at about 1500 feet that was conducive to icing because the temperatures were just below freezing and the air "Had 100 percent relative humidity or was saturated".
Similar icing conditions occurred with the recent Continental Airlines Twin turboprop that crashed at Buffalo New York last month. Also, the March 26, 2005 crash of another Pilatus PC 12/45 fatal to pilot and five passengers. Witnesses in each case say the planes seemed unstable and nosedived.
Former NTSB chariman JIm Hall said that one of NTSBs "Most Wanted" is FAA testing of the ability of turboprop planes to withstand a particular type of icing condition called "Super cooled Liquid Drops" before certification.
The buffalo flight pilots said they could not see forward because of ice buildup on the windscreen. This, plus ice-induced instability could explain the account of one witness for this Montana accident. That witness is a 14-year old CAP, who said the plane jerked to the left before nosediving. He said he thought he was watching a stunt plane because the pilot made so many turns. He may have simply been trying to see out the side windows. The plane was too high and to the right of centerline when it dived. The witness speculated that "He (Pilot) jerked the plane to the left too quickly and lost control of it, but thats just my guess". The pilot tried to pull up, but was too low. Airframe icing could contribute instability.
Ice buildup that is fast and thick from supercooled humidity could also affect the engine thrust as the propellor blades build up a coating and perhaps the engine ingests 100 percent humid air. Icing equipment, especially mechanical ones could not keep up.
All of this seems to indicate there may have been a severe and very fast icing condition that the very experienced pilot could not handle. He was 65 years old, a former air force pilot with thousands of hours, and flew this plane for the last four or five years for a fractional ownership company. The parents of some passengers were fractional owners, and the pilot was also a family friend.
I hope to never experience icing conditions that severe. I have had only one icing experience, and that was enough.
Also, Accuweather.com said that the plane passed through a layer of air at about 1500 feet that was conducive to icing because the temperatures were just below freezing and the air "Had 100 percent relative humidity or was saturated".
Similar icing conditions occurred with the recent Continental Airlines Twin turboprop that crashed at Buffalo New York last month. Also, the March 26, 2005 crash of another Pilatus PC 12/45 fatal to pilot and five passengers. Witnesses in each case say the planes seemed unstable and nosedived.
Former NTSB chariman JIm Hall said that one of NTSBs "Most Wanted" is FAA testing of the ability of turboprop planes to withstand a particular type of icing condition called "Super cooled Liquid Drops" before certification.
The buffalo flight pilots said they could not see forward because of ice buildup on the windscreen. This, plus ice-induced instability could explain the account of one witness for this Montana accident. That witness is a 14-year old CAP, who said the plane jerked to the left before nosediving. He said he thought he was watching a stunt plane because the pilot made so many turns. He may have simply been trying to see out the side windows. The plane was too high and to the right of centerline when it dived. The witness speculated that "He (Pilot) jerked the plane to the left too quickly and lost control of it, but thats just my guess". The pilot tried to pull up, but was too low. Airframe icing could contribute instability.
Ice buildup that is fast and thick from supercooled humidity could also affect the engine thrust as the propellor blades build up a coating and perhaps the engine ingests 100 percent humid air. Icing equipment, especially mechanical ones could not keep up.
All of this seems to indicate there may have been a severe and very fast icing condition that the very experienced pilot could not handle. He was 65 years old, a former air force pilot with thousands of hours, and flew this plane for the last four or five years for a fractional ownership company. The parents of some passengers were fractional owners, and the pilot was also a family friend.
I hope to never experience icing conditions that severe. I have had only one icing experience, and that was enough.
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Icing could compromise Pitot/static and stall warning
Icing could compromise Pitot/static and stall warning. Fast and thick ice buildup could fool the pilot by gumming up the pitot/static and stall indicators. The heating equipment could not keep up perhaps. If you also cannot see out the windows, had changes in airframe behavior because of ice buildup, and perhaps had thrust reduction, all at the same time, and maybe just put down the flaps....
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The pilot was doing a visual approach
The pilot was doing a visual approach. He twice asked to divert to Butte. His last transmission was that he had "One more cloud to get around".
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NTSB press briefing on Tuesday afternoon
As found in AvWeb.com eletter dated March 26, 2009:
Mark Rosenker, NTSB's acting chairman:
"There's a lot of questions, but it begins with that question." The pilot, Ellison "Bud" Summerfield, did not declare any emergency. Rosenker said Summerfield's voice betrayed no sign of stress when he spoke with ATC about the diversion. Investigators will be retrieving more ATC tapes from Salt Lake City and they may request cellphone records for the airplane's passengers to see if they can find any clues for the reason the pilot diverted. Rosenker also said an engine performance recorder was found in the wreckage, but added that it might not offer much help. "It will tell us about the engine and how it's doing, [but] it is not designed for accident investigation," he said. NTSB spokesman Keith Holloway said the safety board already has examined the issue of a known problem with the aircraft's elevator controls, which was addressed in an FAA Airworthiness Directive in March, and determined it had nothing to do with Sunday's crash. Although the 10-seat airplane was carrying 14 people, and icing was reported in the area, neither weight-and-balance issues nor icing factors seem to be standing out as likely causes to the NTSB. Seven of those on board were small children, and the airplane was certified for flight in icing conditions. "Nothing is off the table in this investigation," Rosenker said. "But nothing also, at the same time, is leading us to specific working theories."
The NTSB also said on Tuesday that the airplane's flaps were in the up position, and the landing gear was extended. Also, the airplane's position seemed to be neither on a final approach to the airport's northerly runway nor in a standard traffic pattern, but well off to the side of the runway. That could suggest that the pilot may have attempted a steep turn to enter the downwind leg of the runway approach -- a maneuver that could be especially dangerous if the airplane was heavy or off-balance, or if there was ice.
Mark Rosenker, NTSB's acting chairman:
"There's a lot of questions, but it begins with that question." The pilot, Ellison "Bud" Summerfield, did not declare any emergency. Rosenker said Summerfield's voice betrayed no sign of stress when he spoke with ATC about the diversion. Investigators will be retrieving more ATC tapes from Salt Lake City and they may request cellphone records for the airplane's passengers to see if they can find any clues for the reason the pilot diverted. Rosenker also said an engine performance recorder was found in the wreckage, but added that it might not offer much help. "It will tell us about the engine and how it's doing, [but] it is not designed for accident investigation," he said. NTSB spokesman Keith Holloway said the safety board already has examined the issue of a known problem with the aircraft's elevator controls, which was addressed in an FAA Airworthiness Directive in March, and determined it had nothing to do with Sunday's crash. Although the 10-seat airplane was carrying 14 people, and icing was reported in the area, neither weight-and-balance issues nor icing factors seem to be standing out as likely causes to the NTSB. Seven of those on board were small children, and the airplane was certified for flight in icing conditions. "Nothing is off the table in this investigation," Rosenker said. "But nothing also, at the same time, is leading us to specific working theories."
The NTSB also said on Tuesday that the airplane's flaps were in the up position, and the landing gear was extended. Also, the airplane's position seemed to be neither on a final approach to the airport's northerly runway nor in a standard traffic pattern, but well off to the side of the runway. That could suggest that the pilot may have attempted a steep turn to enter the downwind leg of the runway approach -- a maneuver that could be especially dangerous if the airplane was heavy or off-balance, or if there was ice.
Last edited by avionimc; 26th Mar 2009 at 11:10.
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The 2 Pilatus and the Buffalo Bombardier -8 were T-tails
The two Pilatus accidents - Butte Montana March 2009, and Bellefronte Pennsylvania March 2005 have something in common with the Buffalo New York Bombardier -8 accident January 2009, besides icing conditions. All three aircraft were T-Tail Turboprops with high wing loading. All three appear to have stalled close to the ground and nosed in on approach. Perhaps the T-tail configuration is more susceptable to tail-stall with icing. T-tails are also susceptable to shadowing by the main wing in nose-high attitudes, or fast sink-rates
The Buffalo crash was a commercial flight and the flight recorder has now shown that the plane slowed to 150 kts, and the stick shaker activated. This meant a stall was imminent. Then, a 25 lb force was applied to the stick to RAISE the nose. This is counter to what you would do in a stall situation. The female First Officer sounded tired in her communications with ATC. Could she have been in control and confused? 25 lbs is quite a bit of force. Perhaps the resultant elevator input and attitude change at just under 150 knots stalled the tail if it was iced. The windshield deicing could not keep up and they could not see forward. Perhaps the tail leading edge deice also couldn't keep up. The flaps had just been un-deployed, so perhaps she was countering the effect of the flaps automatically, in spite of the stick shaking. Loss of the lift from flaps could have been a factor at this point. Then again, it seems the autopilot was on, so perhaps this was also a coarse attempt to disengage it.
What would the non-iced stall speed be without flaps, with gear down? Would it be just under 150 kts?
A discussion of the Buffalo accident and the NTSB findings from flight recorder is at:
Daily Herald | Evidence points to crew error in Buffalo plane crash
A very good discussion of icing and turboprops like the Dash 8 is at:
Did Regulatory Inaction Cause or Contribute to Flight 3407 Crash in Buffalo? Nolan Law Group
It still seems to me that Icing was a factor in the Butte crash with a pilot who was so very familiar with his aircraft in normal conditions (2000 hours in type, and four to five years in PC-12's. Would he push it beyond expected limits? He was said to have been a very safe and deliberate pilot. Still, 13 passengers?
The Buffalo crash was a commercial flight and the flight recorder has now shown that the plane slowed to 150 kts, and the stick shaker activated. This meant a stall was imminent. Then, a 25 lb force was applied to the stick to RAISE the nose. This is counter to what you would do in a stall situation. The female First Officer sounded tired in her communications with ATC. Could she have been in control and confused? 25 lbs is quite a bit of force. Perhaps the resultant elevator input and attitude change at just under 150 knots stalled the tail if it was iced. The windshield deicing could not keep up and they could not see forward. Perhaps the tail leading edge deice also couldn't keep up. The flaps had just been un-deployed, so perhaps she was countering the effect of the flaps automatically, in spite of the stick shaking. Loss of the lift from flaps could have been a factor at this point. Then again, it seems the autopilot was on, so perhaps this was also a coarse attempt to disengage it.
What would the non-iced stall speed be without flaps, with gear down? Would it be just under 150 kts?
A discussion of the Buffalo accident and the NTSB findings from flight recorder is at:
Daily Herald | Evidence points to crew error in Buffalo plane crash
A very good discussion of icing and turboprops like the Dash 8 is at:
Did Regulatory Inaction Cause or Contribute to Flight 3407 Crash in Buffalo? Nolan Law Group
It still seems to me that Icing was a factor in the Butte crash with a pilot who was so very familiar with his aircraft in normal conditions (2000 hours in type, and four to five years in PC-12's. Would he push it beyond expected limits? He was said to have been a very safe and deliberate pilot. Still, 13 passengers?
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The two Pilatus accidents - Butte Montana March 2009, and Bellefronte Pennsylvania March 2005 have something in common with the Buffalo New York Bombardier -8 accident January 2009, besides icing conditions. Perhaps the T-tail configuration is more susceptable to tail-stall with icing.
I attended a briefing by Pilatus engineering personnel on the known icing certification program for the PC-12 a couple of years ago. It was an eye opener in terms of the comprehensiveness of the test program. Probably the most thoroughly evaluated FIKI certification for an acft of this class to that time. While it is remotely possible that ice was a factor at Butte, IMO it is the least likely of the scenarios put forward to date.
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Weight and Balance were not issues.
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flaps being up.
I've flown turboprops (twins, many years ago) and one technique I used in mountainious areas was to descend with just gear down. Mind you, I didn't plan to make the approach in that configuration, but descending with gear down increases the rate of descent, while keeping the plane pretty level.
with flaps down the nose is usually down.
has anyone figured out the sun angle? could it have been flicker vertigo?
I've flown turboprops (twins, many years ago) and one technique I used in mountainious areas was to descend with just gear down. Mind you, I didn't plan to make the approach in that configuration, but descending with gear down increases the rate of descent, while keeping the plane pretty level.
with flaps down the nose is usually down.
has anyone figured out the sun angle? could it have been flicker vertigo?
Last edited by protectthehornet; 31st Mar 2009 at 15:10.
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Not really new information, but confirms previous reports
Apr 2, 9:46 AM EDT
Report: Pilot asked to divert, gave no reason
By JOAN LOWY
Associated Press Writer
WASHINGTON (AP) -- A preliminary report on the Montana plane crash that killed 14 people two weeks ago says the pilot twice asked air traffic controllers to divert from the flight's original destination but gave no reason either time.
The National Transportation Safety Board's report was released Thursday. It said an eye witness told investigators he saw the single engine turboprop west of the runway centerline at the Bert Mooney Airport in Butte, Mont., when the aircraft banked to the left and flew farther west of the runway, then it rolled, pitched down and descended out of view.
The report said the pilot of the Pilatus PC-12/45 twice asked air traffic controllers for permission to divert from the flight's original destination of Bozeman to Butte.
© 2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. Learn more about our Privacy Policy.
Apr 2, 9:46 AM EDT
Report: Pilot asked to divert, gave no reason
By JOAN LOWY
Associated Press Writer
WASHINGTON (AP) -- A preliminary report on the Montana plane crash that killed 14 people two weeks ago says the pilot twice asked air traffic controllers to divert from the flight's original destination but gave no reason either time.
The National Transportation Safety Board's report was released Thursday. It said an eye witness told investigators he saw the single engine turboprop west of the runway centerline at the Bert Mooney Airport in Butte, Mont., when the aircraft banked to the left and flew farther west of the runway, then it rolled, pitched down and descended out of view.
The report said the pilot of the Pilatus PC-12/45 twice asked air traffic controllers for permission to divert from the flight's original destination of Bozeman to Butte.
© 2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. Learn more about our Privacy Policy.
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two things
1. additional passengers were taken on at the last stop before the crash. so the previous loading and handling of the plane would have been changed.
2. and I think this is the most important part...why would someone ask twice for a diversion? Once, with a proper acknowledgement would be enough unless:
radio problems/reception problems
or, and this is what concerns me...some mild impairment of the pilot.
2. and I think this is the most important part...why would someone ask twice for a diversion? Once, with a proper acknowledgement would be enough unless:
radio problems/reception problems
or, and this is what concerns me...some mild impairment of the pilot.
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Another 'one more thing'.......
Flight crossed some fairly high terrain with a strong crossing jet stream at FL250. You know what that could mean. (Bumpy).
Anyone ever travel in a car with a back seat full of kids and one of them starts barfing? Can you imagine a close full cabin full of kids that started barfing? And how easily that smell/sight gets contagious?
Pilot goes on oxygen to stave off contagious smell, and requests divert. With descent as well, thought is to get on ground ASAP. Butte was closer, plates were already out, it made sense to go there first. Can you imagine 25 minutes of that going on?
Who knows what kind of shape you or I would be in and try to fly/communicate/land.....
Anyone ever travel in a car with a back seat full of kids and one of them starts barfing? Can you imagine a close full cabin full of kids that started barfing? And how easily that smell/sight gets contagious?
Pilot goes on oxygen to stave off contagious smell, and requests divert. With descent as well, thought is to get on ground ASAP. Butte was closer, plates were already out, it made sense to go there first. Can you imagine 25 minutes of that going on?
Who knows what kind of shape you or I would be in and try to fly/communicate/land.....
