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Continental TurboProp crash inbound for Buffalo

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Continental TurboProp crash inbound for Buffalo

Old 16th Feb 2009, 00:06
  #381 (permalink)  
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Mad (Flt) Scientist..Thats a reasonable reply so if you and your listeners dont mind I would like to bring up the center of gravity on the Q400 then I will keep quiet.
IF there are 10 windows forward of the wings which could equate to 40 passengers each sitting 4 abreast AND if each passenger weighs 180 lbs the weight forward of the wings is 7200 lbs plus crew and engines lavatory/water. The plane is nose heavy.

In short I request someone to inspect the cables for the trim tabs on the elevators. I bet those tabs are used constantly when in flight to keep the nose up (trim the plane). Inspect the tension on those cables and check the turnbuckles. This craft is nose heavy and those cables can and do stretch. If theres no trim tabs--well there you have it.007
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Old 16th Feb 2009, 00:14
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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...
I don't fly the Q400 so I can't comment on how its' autopilot works but the medium and heavy jets I fly use the elevators to control pitch and then use the trim system to remove those inputs. I've yet to see any guidance from my company, my certifying authority or the manufacturer of my type to suggest that I should disconnect the autopilot in icing conditions - should I be concerned?
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Old 16th Feb 2009, 00:32
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how could the nose come up? was the plane's cargo suddenly shifting rearward?

had any flights been cancelled and a double load of luggage from the day before placed on board and not accounted for?

what are the non ice contaminated stall characteristics of this plane? if a plane has a shaker and a pusher it must not be conventional.
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Old 16th Feb 2009, 00:40
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Latest news, was on autopilot in icing - not confirmed by FDR as yet
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Old 16th Feb 2009, 00:57
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If anyone wants to get a powerpoint presentation on a system that would have told the crew of the exact situation about icing on the tailplane, please pm me.
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Old 16th Feb 2009, 01:01
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Ice Protection REF Speed Switch?

Just throwing this out there, if you reference this picture of the overhead panel. Photos: De Havilland Canada DHC-8-402Q Dash 8 Aircraft Pictures | Airliners.net

There is a switch on the Ice Protection sub panel that says "REF SPEEDS" I'm curious as to how much this would alter the speeds in this setting's and hypothetically left in the normal or off position could this have been a factor in this accident.
I'm sure the good people down at the NTSB will be looking into this eventually but are there any Q400 Drivers on here that could shed some light?
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Old 16th Feb 2009, 01:35
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Security 007:

You can't assume that an aircraft is inherently nose or tail heavy just by looking at its outward physical appearance or seating configuration. The aircraft's loading (and the resulting COG location) is carefully calculated before each flight.

On any given flight, an aircraft may be slightly nose or tail heavy in relation to its "standard" CG, but it a regulatory requirement that the loaded COG must fall within well-defined limits that would prevent any situation where excessive control surface deflection or trim inputs would be required to keep the aircraft flying level.

That's not to say that mistakes don't happen. Several years ago, a DC-8 freighter crashed on takeoff in Miami because an improperly-secured load broke loose and slid aft when the nose was raised, causing a loss of control.

Crashes due to out-of-limit CG conditions are (unfortunately) not uncommon in small, privately owned aircraft, but very rare in commercial operations.

It would be incorrect to say that the Q400 is by its nature a "nose heavy" aircraft. If it were, it would never have been certified.

At the latest NTSB press conference, they said the the FDR data shows no unusual trim inputs were being commanded by the autopilot, which would tend to rule out CG issues as a contributing factor.

In any case, I'm sure that the NTSB will look closely at the calculated loading for this particular flight - fuel, passengers and baggage.

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Old 16th Feb 2009, 01:52
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Crashes due to out-of-limit CG conditions are (unfortunately) not uncommon in small, privately owned aircraft, but very rare in commercial operations.
There was Air Midwest 5481 back in 2003.

ASN Aircraft accident Beechcraft 1900D N233YV Charlotte-Douglas International Airport, NC (CLT)

However, that was on take-off and needed more holes in the cheese than just a CG a bit aft of the limit.
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Old 16th Feb 2009, 01:56
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Was there any mention in the latest briefing as to how long this crew had been on duty the day of the accident ?
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Old 16th Feb 2009, 02:17
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After investigating this balloon concept to deice the wings theres doubt in its design and how it will continue to function as it was intended. In short--here is what I have initially concluded (in part).

This inflatable membrane concept has several drawbacks that may cause it not to function as intended.
I have to point out that this “membrane concept” has been in service since the 1930s, and that all this drama over it has only occurred in the past few years. It is a proven technology with a long history.
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Old 16th Feb 2009, 02:46
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airspeed pitot/static probe heat flybe BE688

Airspeed indications could be extremely important here.
As somebody stated earlier it seems very unlikely both pilots would let a plane get so slow in such a critical phase of the flight.
Reminded me of the Flybe incident where the IAS and altitide indications became erroneous due to the pilots forgetting to activate the pitot/static probe heat.
In the report it is stated that even the standby IAS indicator
failed -Luckily the flybe crew had altitude and therefore time to diagnose the problem and take action(see report below)however this could have been another story had the airspeed anomalies started to happen on final approach while low, slow and vulnerable.

It seems more plausible that someone could forget to flick the probe heat switches than for a certified icing system which we know was switched on to cause any problems in moderately cold conditions.Looks more like a standard stall due to a faulty IAS indication and subsequent lack of airspeed.
The pitot heat switches dont have much throw as shown in the AAIB Flybe report and could be mistaken for all switches on despite all 3 actually being off.

A FlyBE Dash 8-400, registration G-JECG performing flight BE688 from Edinburgh to Belfast City with 71 passengers and 4 crew, encountered multiple instrument failures shortly before reaching FL160 after takeoff while climbing through heavy precipitation in icy conditions, the failures consistent with freezing of the pitot/static ports
Full Report -very interesting
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Old 16th Feb 2009, 02:50
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Link to NTSB Briefing Video

wgrz.com | Buffalo, NY | Video
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Old 16th Feb 2009, 02:51
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The following excerpt is from

Bombardier Q400 Flight Evaluation

I leveled at 15,000 feet to perform some clean stalls. Our weight was now 52,480 pounds, and I slowed until the stickshaker activated at 107 KIAS. Stall buffet occurred at 102 KIAS. A stickpusher will be installed on the Q400, but because the stall testing was still ongoing, the system was not yet operational.
Next I performed a stall with 15 degrees of flaps and a 20-degree bank, and the stickshaker activated at 91 KIAS. In the next stall--performed with gear extended, flaps at the landing setting of 35 degrees and Vref at 112 KIAS--the stickshaker activated at 80 KIAS.
In all the stalls, the aircraft was very responsive, and control was positive in both pitch and roll. The aircraft tends to wallow a little as the power comes up, which is typical for a turboprop airplane as the propellers speed up unevenly. The flaps extend smoothly without much ballooning and have very little rumble even when fully extended to 35 degrees.
In the last stall--performed at a flap setting of 15 degrees with the gear down and Vref at 117 KIAS, the stickshaker activated at 93 KIAS. This Vref speed did not have a 5-knot safety factor.
For a single-engine approach, a flap setting of 15 degrees is used to ensure adequate climb performance in the event of a go-around. I set up an approach with a Vref of 117 KIAS, flaps 15, and gear down. I started a go-around, and Warner pulled an engine to zero thrust. The Q400 was very controllable and required a determined lowering of the nose to maintain V2 in the climb. We were climbing at 900 fpm single-engine, and I did not have to apply excessive force to the rudder.
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Old 16th Feb 2009, 03:17
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Lightbulb Appropriate links

If any of you have not seen the NASA position on Tail Plane icing here it is.

Tailplane Icing

For those of you still pushing ice bridging this should put that theory to rest.

Commercial & Business Aviation Advisory Circulars

These were sent to me by a very well qualified individual.

Hope this helps.
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Old 16th Feb 2009, 03:19
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Mad (Flt) Scientist wrote

Electric deicing is not superior to boots - it has a number of problems of its own, including the power required to get equivalent performance, and the need to generate that power from somewhere.

The most effective system around today is almost certainly bleed air used to heat the surface
Consider that the Boeing 787 (will) use electric heating in the wings for both de-ice and anti-ice, not bleed air. Boeing expects this technique to be both superior and energy saving.
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Old 16th Feb 2009, 03:43
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From the AP:

The plane was about six miles from the runway when it started lurching dramatically, pushing passengers into their seats with twice the normal force of gravity, and was only about 1,600 feet above the ground, too low and possibly too slow to regain control, according to preliminary information from investigators.

Icing on the windshield and the front edges of the wings, which was reported by the crew, is suspected of having been a factor but is far from proved.

Continental Connection Flight 3407, from Newark Liberty International Airport, crashed into a house in Clarence Center, N.Y., killing all 49 people on board and one man inside the home.

Closer examination of the cockpit voice recorder and the flight data recorder from the plane, a twin-engine turboprop Bombardier Dash 8 Q400, shows that 26 seconds before the recordings were stopped by the impact, a warning alerted the crew that the plane might lose lift and fall out of the sky, and an automatic system tried to push the nose down to gain airspeed. But soon the nose climbed to 31 degrees, far steeper than the steepest normal climb. Suddenly, the nose plunged to a downward angle of 45 degrees, almost like a fighter plane breaking off to dive. Then it rolled to the right, beyond 90 degrees, all the way to 106 degrees.

Steven Chealander, the member of the safety board assigned to the investigation, also said that the crew had turned on the plane’s sophisticated de-icing system shortly after leaving Newark, long before the crash. Such systems can sometimes be ineffective if they are turned on too late, but that does not appear to have been the case here.

And the weather conditions, as they were described to the crew before takeoff and as the captain and first officer discussed en route, did not appear atypical for a winter night in the Buffalo area. “We don’t know that it was severe icing,” Mr. Chealander said. “They didn’t say that it was severe icing,” he said, referring to the cockpit crew, and “the weatherman didn’t say that it was severe icing.”

If the trouble began with a huge upward jump of the nose, then another hazard of turboprop aircraft, ice buildup on the tail, was probably not an issue.

Sometimes ice limits the ability of the tail to perform its main function, which is to control the up-and-down movement of the nose. Normally the tail exerts a downward force, moving the nose up as pushing down on one end of a seesaw will raise the other end. Sometimes if ice builds up, the tail will still function well enough for a plane to cruise in flight, but will not work well enough when the crew makes a change in the configuration of the airplane, by, for example, lowering the flaps before landing.

The plane started losing control as the crew lowered the flaps and the landing gear.

Asked why the nose rose, Mr. Chealander said, “There’s a lot of possibilities.” The safety board usually takes a year to 18 months to reach a conclusion, although often within a few days of a crash, the general outlines are clear. That is not yet the case here.

The accident was the first fatal crash of a scheduled airline flight in the United States since 2006, and the deadliest since November 2001, when American Airlines Flight 587 crashed in Belle Harbor, Queens, killing 265 people.

The crash of Flight 3407, particularly because the crew had reported icing conditions, has reignited a debate about the use of the autopilot. The safety board, following a crash in 1994, pointed out that using the autopilot in icing conditions can mask the problem. The plane can fly along the desired path without giving any sign that the controls are becoming sluggish or hard to manipulate, both signs of icing. A human who was flying the airplane manually might feel those effects.

The Continental Connection crew used the autopilot until it shut itself off, about 26 seconds before impact.

But Mr. Chealander on Sunday read from the airplane flight manual, written by the manufacturer, Bombardier, and adopted by Colgan Air, the operator that Continental contracted with. It allows for use of the autopilot unless the plane faces “severe icing conditions.”

“Thus far we haven’t determined that it was severe icing,” he said. A weather team is examining that question.

Another issue for regional airlines like Colgan is that they tend to employ entry-level airline pilots. Mr. Chealander said the captain, Marvin Renslow, 47, had 3,379 hours of flying experience, which is fairly high, but he had been flying the Dash 8 only since December. The first officer, Rebecca Lynne Shaw, 24, had 2,244 hours, which Mr. Chealander said was “experienced as well.” She had 774 hours in the Dash 8.
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Old 16th Feb 2009, 03:54
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Would be good to know the crew duty day and FDT that the crew performed prior to this.
Could have been a very important factor.
But its only been a few days, surprised the NTSB has released so much information this soon.
Sure we will all see it in a CRM recurrent in the future.
No one thing causes an accident, its usually a combination of things that contribute to the problem.
Way too early for this.
Prayers for the family and crew.

Last edited by Earl; 16th Feb 2009 at 04:17.
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Old 16th Feb 2009, 04:28
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The thing that gets me is that the determination of "severe icing" seems to be subjective, and up to the crew to decide.

Therefore, one crew's assessment of conditions described as "severe" might be interpreted by another as "moderate" when flying through the same airspace, and vice versa.

It's kind of like assessing windshear, turbulence and even visibility. There are no hard and fast rules...
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Old 16th Feb 2009, 04:30
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Mad (Flt) Scientist While you want to know the AS for reconstruction, you also want to know what the crew saw. Having only (for example) standby IAS recorded would make it impossible to know what the crew were actually flying in terms of AS
Never flown turboprops as such, but in the jet that I fly we also have independent [GPS/IRS] ground speed and wind vector [speed & direction]displays which are included in the instrument scan during final approach.

StudentInDebt ". . . I've yet to see any guidance from my company, my certifying authority or the manufacturer of my type to suggest that I should disconnect the autopilot in icing conditions - should I be concerned?"
I think that you do have some guidance; because there must be something in your manual somewhere that says that you are not constrained from using common sense, and that not all situations, abnormalities or emergency situations can be addressed in your QRH.

As to icing "conditions" it may not be cause for disconnecting your A/P, but if you're "iced up" [Leading edges, window frames . . .] it's cause for increasing airspeed and delaying flap extension and an understanding that your A/P does not "know" how sluggish your airplane has become. Just as your auto brakes do not "know" when you're sliding off the centerline and potentially off the pavement.
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Old 16th Feb 2009, 04:31
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Some of the post on here are way out on the definition of icing.
Anti ice is usually for the engines, most airlines for example are 8-10 degrees TAT (total air temperature ) and visible moisture, with some other limitations usually based on the engine manufacturer.
De-Ice systems are after entering icing conditions such as wing de-ice etc.
Big difference between the two.
Sorry just had to put this in as I read a few post that showed many did not understand the difference.
Wait to the final report, speculation is useless at this point.
I would like to hear more about crew duty time limitations for this flight.
Perhaps more to this accident with other factors.
Maybe nothing but worth looking at.

Last edited by Earl; 16th Feb 2009 at 05:05.
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