I live like 15 minutes from the site. I dont understand why it crashed. De-icer?? I heard a couple freaky stories about it too. I just thought I would see everyones thoughts.

 

From my understanding the de-icing system on this plane uses expandable rubber boots to remove ice from the leading edges of the wings AFTER ice starts to accumulate. Ice builds up, the boots are inflated and ice gets broken off. The system is then turned off (deflated) and the process repeats.

One theory is that the pilot turned on the de-ice system too soon, ice built up on the inflated boots, rendering the system useless since it can no longer expand to break up the ice. Everything is a theory at this point although it certainly appears that ice played a part somehow. Inexperience of the pilot in this type of plane may also be a factor. Low altitude, low speed, darkness, limited visibility, and so forth are probably all contributing factors.

Take it from me, ice can not only affect the flying characteristics of the plane (think driving your truck on flat tires), it will also mess (mentally) with your ability to fly the plane - especially a plane that has NO de-icing system other than getting below the freezing level.

 

Jim,

Here's my understanding, with a disclaimer that I am NOT pointing my finger at anyone involved with the aircraft, the pilot, co-pilot and crew.
My post is for conversational purposes, only.
I'm not a pilot, but, I know a little about aircraft and I'm very interested in them.


From what I've heard, the pilot only had like 300 hours in that 'type'.
(Not a lot of time, IMNSHO.)
The plane was on auto-pilot. (Some say that it should've been flown manually in that much 'icing' conditions.)
I don't know whether or not the plane should have been manually.
The aircraft was doing 'fine' until the landing gear was lowered and the flaps were lowered.
Plane too slow for icing condition, it looks like.
More speed to compensate for lack of lift?
I'm hearing that the pilot may have used the procedure for a previously flown aircraft type, when the plane went into a stall.
Over-correction to 'stick shaker' and 'stick pusher' impulse.
With that said, the reports say that the plane nosed over, then banked to approximately 45° to the left, then sharply 105° to the right, which is/was several degrees beyond where 'lift' stopped/ended.
The plane lost 800 feet in mere seconds, from the news reports.
If the pilot recovered (which all indications show), he may have just ran out of airspace before getting that aircraft back to a high enough altitude to land at the airport.

Sad. Very sad.

 

300 hours should be enough in a type to know how to fly it correctly BUT his First Officer had several times more experience in the Dash-8 and had she been flying it, who knows.

Company policy and NTSB RECOMMENDATIONS dictate that the Autopilot should have been OFF in icing conditions.

If things got bad for the pilot, instinct probably did take over causing him to revert back to what he knew best which may have been another type of plane. Low wing and high wing planes do handle differently.

The cause of many aircraft accidents has been "insufficient altitude for the maneuver being attempted".

 

From what I've heard they put the least experienced pilots in these planes. My brother in law told me that the woman whose house it landed on could hear screaming when the plane hit. That gives me goose-bumps. Man you have to cherish everyday you got!!

 

well autopilot only hides the sluggish control inputs - it wont affect icing.

aircraft fly at a certain angle of attack (AOA) which is nose up, to land such that you can see the runway, the nose has to come down, plus you have to have the ability to enter a glideslope - flaps do this and bring the nose down by changing the chording of the wing.

gear down pulls the nose even further.

the ice will accumulate on the negative pressure portion of the wing chord, when flap come down and the AOA lessens, the negative pressure area is now positive pressure and its shape is changed, which in effect lifts air from the ailerons. deicing boots will not affect his area of the wing

prop planes are especially vulnerable compared to jets - the props push air over the wing much faster than what a jet experiences, hence the negative pressure area next to the wing root is larger, and more ice can form at higher ambient temps. At the time of this crash, it was above freezing in the area! (my car said 39* but Im south of them, but in the same weather system)

I was driving in that weather at the time of the crash - the area is by nature very 'squally' and with the week of warm temps, most of erie is ice free - hence a lot of airborne moisture.

go back to the american eagle ATR-72 crash about 10 years back - those pilots were in command from 8000ft on down.

if the dash 8 is adjucated the same as the -72 to be questionable in cold weather - this is gonna put a lot of regional airports or feeder route out of bizness.

 

I'm wondering if you understand what you wanted to say and just said it wrong or what but I'd like to attempt to clarify a couple things.....

Of course the use of AP won't affect whether the plane gets ice or not - that is the very reason NTSB recommends (they can't require) and why the company policy was to disengage AP in icing conditions. Even so, the AP should have disengaged automatically as soon as the controls were moved beyond a certain amount against the autopilot by the human pilot.

Planes don't have to fly nose up to land except for the last few feet of altitude, when they flare. The flaps are used to give the plane more lift at lower airspeeds. You don't need to change angle of attack, or more accurately the pitch attitude, to see the runway at all. In fact, in an instrument approach you may not even see the runway until the last couple hundred feet or less. Intercepting a glideslope has absolutely nothing to do with flaps or nose up or down attitude. On a high wing plane. adding flaps will bring the nose up. On a low wing, flaps will bring the nose down. Either way, corrections are made to maintain desired airspeed.

Ice at the wing root is the best place for it. At that point on the wing a stall is least dangerous as it is close to the axis of rotation - shorter moment-arm than if it were at the tip of the wing.

If it was 39° where you were on the ground, it was probably well below freezing at the altitude they were flying at. The ice was probably on the aircraft as they descended, adding flaps and gear "dirtied" the aircraft and may be what caused the loss of control. It is also entirely possible that the ice formed on the tail which could also explain the loss of control and extreme rolls and pitch changes.

I agree with you 100% though regarding the Dash-8 and ATR. There are a lot of Dash-8's out there. Prohibiting them from flying anywhere near icing conditions would be a huge hit to the aviation industry.

 

Gotta remember that wind speed makes a huge effect on water vapor. I've gotten in my truck to head to work in slightly above freezing weather, and had the windshield ice over before the end of the road. Sit there for a couple minutes, and it all melts right off.
I remember hearing of problems with pneumatic de-icers years back, and though I heard they were going to be phased out.
A part of the problem was definitely airspeed, icing usually increases the stall speed. Drop the landing gear, and the extra drag drops your airspeed. The flight recorder indicates a textbook stall, if a bit asymmetrical.

 

a glide slope is easier to hit with a pitch closer to zero (pitch might be zero, but once gliding downward the AOA is high again), or else the aircraft behaves like a lift body (see shuttle), which would be ver ver bad for a high tail aircraft and in the event of a go around, it is very hard to accelerate when nose up (see: deH comet)

while its true that plans can fly trimmed nearly level or slightly nose down(see: p51 on ground patrol) it is very wasteful on fuel and requires more throttle to have the same lift as reduced power settings.not to mention if you are nose level, the addition of flaps (they extend very outward and down aft, and slightly down front) would require a plane to fly trimmed nose down.

the flare out at the end of an approach, is a return from nose down/level to nose up, not the other way

please note, to have untrimmed zero pitch on a fixed wing aircraft, assuming it was at constant altitude, the AOA would be very small and thusly lift, unless a lot of power was applied to keep speed up.

but anyways, I was talking on a pilot site earlier, some have mentioned the pitching indicates a tail stall due to ice.