Continental TurboProp crash inbound for Buffalo
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looks like the WSJ might have gotten something from a controller:
(The aircraft) had veered to the left of the final approach path to the runway at Buffalo Niagara International Airport and was in a steep right turn when it disappeared from air traffic controllers' radar screens, according to people familiar with early details of the investigation.
The plane was roughly six miles northeast of the airport when air traffic radar showed that it was slightly to the left of the final approach course. It began a right turn, but instead of straightening when it picked up the radio signal from the airport's instrument landing system, it continued turning right almost 180 degrees and disappeared from radar, said a person familiar with the situation.
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@Robert Campbell:
While I was never privileged to fly the DC-3/4 I started flying turboprops a few years before the FAA de-/anti-icing review following the Roselawn accident. Waiting for ice to build up was what we were taught and did.
After the FAA review we "switched" to switching on the boots when entering icing conditions. While flying along and over the alps all year long I never saw any "bridging" and switching on the prop heat right away saved the pax a lot of "banging" from chunks of ice suddenly hurled against the fuselage.
The FAA review specifically differentiated between suction-powered "low power" boots on older piston A/C (some of them without ridges as far as I remember) and bleed-powered systems on turboprops the FAA found to be powerful enough to avoid bridging.
I too found the Dash 8 to be very capable in icing conditions and never encountered a situation where I would have been unable to continue on course due to icing.
While I was never privileged to fly the DC-3/4 I started flying turboprops a few years before the FAA de-/anti-icing review following the Roselawn accident. Waiting for ice to build up was what we were taught and did.
After the FAA review we "switched" to switching on the boots when entering icing conditions. While flying along and over the alps all year long I never saw any "bridging" and switching on the prop heat right away saved the pax a lot of "banging" from chunks of ice suddenly hurled against the fuselage.
The FAA review specifically differentiated between suction-powered "low power" boots on older piston A/C (some of them without ridges as far as I remember) and bleed-powered systems on turboprops the FAA found to be powerful enough to avoid bridging.
I too found the Dash 8 to be very capable in icing conditions and never encountered a situation where I would have been unable to continue on course due to icing.
I REALLY SHOULDN'T BE HERE
Uncle Jay,
Having flown the type in question I can say that your "inviolate rule" is an inappropriate way to fly this particular aircraft except under completely smooth air conditions. It is not speed stable even with the flap in the 35 position. As you get into the lower power settings the TLA varies the propellor pitch and has a marked effect on the overall drag of the aircraft, especially at the standard 1020rpm landing setting.
A few further points:
Generally there are plenty of visual cues to when the airframe is icing up, namely the wiper spigot, under the wiperblade itself, the leading edge and the spinners all show ice up nice and clearly. As has been mentioned, the aircraft has a very good (flashing amber on the ED) attention getting display if ice has been detected by either ice detector and stall reference speed switch has not been selected on. This switch however is not in any way linked to the actual operation of the de-ice/anti-ice system; it reschedules the trigger alpha for stick-shaker and pusher.
The AOM mandates the disconnection of the AP under severe icing conditions to prevent any possibility of inappropriate trimming by the AP.
The de-icing system, though not perfect is very good at least at letting you know when there is a problem with it.
sr
Having flown the type in question I can say that your "inviolate rule" is an inappropriate way to fly this particular aircraft except under completely smooth air conditions. It is not speed stable even with the flap in the 35 position. As you get into the lower power settings the TLA varies the propellor pitch and has a marked effect on the overall drag of the aircraft, especially at the standard 1020rpm landing setting.
A few further points:
Generally there are plenty of visual cues to when the airframe is icing up, namely the wiper spigot, under the wiperblade itself, the leading edge and the spinners all show ice up nice and clearly. As has been mentioned, the aircraft has a very good (flashing amber on the ED) attention getting display if ice has been detected by either ice detector and stall reference speed switch has not been selected on. This switch however is not in any way linked to the actual operation of the de-ice/anti-ice system; it reschedules the trigger alpha for stick-shaker and pusher.
The AOM mandates the disconnection of the AP under severe icing conditions to prevent any possibility of inappropriate trimming by the AP.
The de-icing system, though not perfect is very good at least at letting you know when there is a problem with it.
sr
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NTSB reports excellent data on data and cvr. The gear had been lowered a minute before the data ended, and as it began large excursions, attempts were made to raise the gear and retract flaps 15.
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NTSB reports (from initial FDR and CVR readout) that plane was at FL160 and requested descent to FL120 to clear haze. ATC cleared them to FL110. Pilots discussed significant ice buildup on the wings and windshield. Aircraft deice was selected just prior to these comments.
1 minute prior to the end of recording, landing gear was selected down. 20 seconds later, flaps 15 were selected. Immediately following flaps to 15, a series of violent pitch and roll excursions occurred. The pilots tried to raise the gear and flaps prior to impact.
1 minute prior to the end of recording, landing gear was selected down. 20 seconds later, flaps 15 were selected. Immediately following flaps to 15, a series of violent pitch and roll excursions occurred. The pilots tried to raise the gear and flaps prior to impact.
Last edited by Flight Safety; 13th Feb 2009 at 20:38.
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From the NTSB brief:
Both the FDR and CVR are in excellent shape and have had an initial read in Washington.
The crew discussed significant ice buildup on the descent, airframe deice was selected on.
About one minute before the end of the recording, gear was selected down, 20 seconds later flaps 15 was selected, severe pitch and roll excursions started almost immediately after the flap selection.
The gear and flaps were raised and the recording ended soon afterward.
The briefing is being conducted by Steve Chealander, a former American Airlines captain and USAF Thunderbird.
Both the FDR and CVR are in excellent shape and have had an initial read in Washington.
The crew discussed significant ice buildup on the descent, airframe deice was selected on.
About one minute before the end of the recording, gear was selected down, 20 seconds later flaps 15 was selected, severe pitch and roll excursions started almost immediately after the flap selection.
The gear and flaps were raised and the recording ended soon afterward.
The briefing is being conducted by Steve Chealander, a former American Airlines captain and USAF Thunderbird.
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NTSB briefing:
crew briefed ils approach to 23 Buffalo
discussed vis 3m snow and mist
at 16000 vis hazy so requested 12000
shortly after cleared to 11000
FDR showed airframe de-ice selected on, followed by a cockpit discussion of significant ice on windshield and leading edge of wings
final events timeline:
end-of-recording minus 1 min: landing gear selected down
eor minus 40 secs :flaps 15 selected
"within seconds of flap selection": "series of severe pitch and roll excursions"
"shortly after that" : crew attempted to raise flaps and gear "just before the end of the recording"
crew briefed ils approach to 23 Buffalo
discussed vis 3m snow and mist
at 16000 vis hazy so requested 12000
shortly after cleared to 11000
FDR showed airframe de-ice selected on, followed by a cockpit discussion of significant ice on windshield and leading edge of wings
final events timeline:
end-of-recording minus 1 min: landing gear selected down
eor minus 40 secs :flaps 15 selected
"within seconds of flap selection": "series of severe pitch and roll excursions"
"shortly after that" : crew attempted to raise flaps and gear "just before the end of the recording"
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Approach speed and conditions
Looking at the posts, and after hearing the NTSB presser, had a few q's.
- Are the ice detector or stall ref speed switch two of the parameters recorded on the FDR?
- What are the approach speeds for no icing vs. icing conditions in this aircraft?
- Is the pitch and roll "excursion" reported by the NTSB after flaps 15 a typical indication of an icing related stall event?
Sound similar to another turboprop accident in (Ohio?) a few years ago originating at DTW that I believe was caused by a misconfigured aircraft flying too slowly in severe icing...
- Are the ice detector or stall ref speed switch two of the parameters recorded on the FDR?
- What are the approach speeds for no icing vs. icing conditions in this aircraft?
- Is the pitch and roll "excursion" reported by the NTSB after flaps 15 a typical indication of an icing related stall event?
Sound similar to another turboprop accident in (Ohio?) a few years ago originating at DTW that I believe was caused by a misconfigured aircraft flying too slowly in severe icing...
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Sounds like the Roslawn American Eagle ATR 72 accident!
The NTSB report exessive pitching and roll before this Q400 crash. The same thing happend to the ATR!! NTSB says it happend after selection or retraction of flaps. The same happend in Roslawn. The first roll came after the copilot selected a lower flap setting. ATR has since recommeded flying manually in severe icing, and if roll accurs, select more flaps.
The ATR also has a ice detector, and on that accident the equipment was on and working. The ATR, however, has a so called 'critical wing', which can lead to ice buildup behind the boots. ATR has after the Roslawn accident recommended all operators to install a new larger boot on the wings.
Q400 pilots; do the Q400 have a critical wing?
Caution!! This is just my speculation! Obviously we must wait for the final report!
The NTSB report exessive pitching and roll before this Q400 crash. The same thing happend to the ATR!! NTSB says it happend after selection or retraction of flaps. The same happend in Roslawn. The first roll came after the copilot selected a lower flap setting. ATR has since recommeded flying manually in severe icing, and if roll accurs, select more flaps.
The ATR also has a ice detector, and on that accident the equipment was on and working. The ATR, however, has a so called 'critical wing', which can lead to ice buildup behind the boots. ATR has after the Roslawn accident recommended all operators to install a new larger boot on the wings.
Q400 pilots; do the Q400 have a critical wing?
Caution!! This is just my speculation! Obviously we must wait for the final report!
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Ice induced stall?
My prediction, based on what is known, is this Dash 8-400 iced up bad while on approach (with on auto-pilot on) then outright stalled, probably as it leveled off to it's assigned altitude. The engine power isn't coupled to the autopilot. The tail section is intact on the ground and the debris is hardly spread out.
Cause of the stall? Faulty deice boots on the tail or wing(s). Crew didn't
select wing/tail anti-ice. With integrated windshield heat nowadays always selected on, you don't necessarily suspect ice accumulation unless you turn on the wing inspect lights and have a look at the leading edges.
Having said this, question was asked if it may have hit migratory birds bad enough to cause a double engine out; although not probable it can't be
totally discarded. If we could see the props in all the pictures it would
confirm this right away.
Glad they recovered both the CVR and FDR to get to the bottom of it so we don't have to speculate too long. I'm sure Bombardier is in white knuckle mode. This airframe was a late serial number, i.e. fresh off the production
line.
Cause of the stall? Faulty deice boots on the tail or wing(s). Crew didn't
select wing/tail anti-ice. With integrated windshield heat nowadays always selected on, you don't necessarily suspect ice accumulation unless you turn on the wing inspect lights and have a look at the leading edges.
Having said this, question was asked if it may have hit migratory birds bad enough to cause a double engine out; although not probable it can't be
totally discarded. If we could see the props in all the pictures it would
confirm this right away.
Glad they recovered both the CVR and FDR to get to the bottom of it so we don't have to speculate too long. I'm sure Bombardier is in white knuckle mode. This airframe was a late serial number, i.e. fresh off the production
line.
Gender Faculty Specialist
WilliJet, The Increased Ref switch increases the low speed awareness cue by 20 knots, so the approach speed is also increased by 20 knots.