Colgan 3407 NTSB Animation

[Raskal]

I've read some pretty dumb things on this thread, but you take the cake with this comment. Had the pilot of this aircraft been monitoring his airspeed, there wouldn't have been accident to be discussing right now.

Agreed, I have no problem when FO's do the "speed checks" call and I'm occasionally guilty of saying it myself (it was a callout at my previous job). Especially when tired sometimes helping yourself and the other guy out by verbalizing what you're doing is beneficial and can prevent the stupidity we're all occasionally guilty of.

Another example is I'll usually call "anti-ice coming on" so the FO knows what I'm up to when flipping switches outside of normal flows. Is this an official call in the FOM? No. If an FO reached up and turned anything on without letting me know what he's up to am I going to react? Damn straight.

 

[PeanuckleCRJ]

Raskal- well said. That is just good cockpit coordination and communication. He calls for something, I repeat the command back as I'm doing it.... I'm select the engine anti-ice on, I'm calling out that it's coming on.

It's just basic CRM.

 

[Be 23]

ooops

 

[igneousy2]

As far as I can tell it seems many of you are being too hard on the FO for putting the flaps back up. The FAF is the point in time where the PNF is the most task saturated. At a previous 121 carrier I was taught that if you move something and everything gets f-upped...un-f*** it by changing it back. My guess would be that the FO was heads down, sensed something was wrong and looked at the first instrument that you go to which is the Attitude Indicator. She notices that she is rolling through knife edge and retracts the flaps, probably thinking she had an asymetrical flap deployment. It takes a few seconds to go from PNF to FP. Even longer if you're brand spanking new and not 100% confident at what you are looking at.

Although many of the other criticisms are valid, my impression is that the Captain froze and the First Officer was trying to find "A way" all the way to the ground....she just didn't have enough experience to recognize what was going on-quick enough to do anything about it. I do agree with the statment that was made that had she been at the controls this probably would have had a much happier ending.

 

[imacdog]

The captain didn't freeze - he did worse by making the wrong corrective inputs.

 

[Lampshade]

Low airspeed, stick shaker and stick pusher but you think the FO though it was asymmetric flaps?

 

[Crossky]

I have never heard of retracting the flaps during a stall recovery. What kind of plane are you talking about? When you retract the flaps, you effectively increase the wing's angle of attack. This of course is not desirable in a stall recovery. It kinda goes along the same lines as a windshear recovery. Max thrust and don't touch the configuration until you are clear of it.

Can't believe no one corrected your post till now. Please, go read an aerodynamics textbook before commenting on anything technical.

Retracting flaps REDUCES the angle of attack, and extending flaps INCREASES AoA. The Angle of Attack (AoA) is the angle between the relative wind and the chord line of the wing. The chord line is the line between the leading edge and trailing edge. The trailing edge changes when the flaps are extended or retracted. When flaps are extended, the trailing edge lowers relative to the existing chord line, the chord line steepens relative to the relative wind, and the AoA increases.

BTW lift and drag increase with flap extension as well, lift more than drag at first, then drage more than lift as flap extension reaches full.

Also, flaps are always retracted during a stall recovery, if they were extended. This of course has to be done at a safe airpeed and AoA during the recovery procedure.

The FO should have NEVER retracted the flaps until commanded to do so by the CA. The FO should have called out 'AIRSPEED' long before the shaker occured because the CA let it get way too slow. The CA let the plane get way too slow, overcontrolled, and did not perform a proper stall recovery.

peace out.

 

[ultrarunner]

Low airspeed, stick shaker and stick pusher but you think the FO though it was asymmetric flaps?

With all the crap those two were yapping about on the way up from ERW, what on earth makes you think she was AT ALL in the game of acting as an SIC...

$hit, she wasn't thinking at all!

 

[FlyinFife]

The FO should have NEVER retracted the flaps until commanded to do so by the CA. The FO should have called out 'AIRSPEED' long before the shaker occured because the CA let it get way too slow. The CA let the plane get way too slow, overcontrolled, and did not perform a proper stall recovery.

While I don't disagree with anything you have said, I believe the REF & APP speeds were bugged at 114 & 119 (As per the CVR transcript). At my company we don't necessarily have to make an airspeed callout until REF +10. Taking that into account, I don't find it odd that there were not any airspeed callouts.

At the same time, that could explain the FO's "Uhhhhh" comment just as the stick shaker was occuring: she's busy, makes the switch to tower, makes the call, selects the flaps, and looks down at the airspeed just a few seconds too late and sees their airspeed coming up to the red tape which in her mind is not supposed to be there. She says "Uhhhh", the stick shaker goes off, and the rest is history.

That being said, either one of them should have seen the red tape approaching before it got to that point.

 

[LazyLightnin']

With all the crap those two were yapping about on the way up from ERW, what on earth makes you think she was AT ALL in the game of acting as an SIC...

$hit, she wasn't thinking at all!

She wasn't really the one doing the yapping. It was mostly el capitan in the left seat spouting off the entire flight. Most of her comments were "uh huh" and "yeah". As in, "I hear ya, but still don't give a shlt"

 

[Lilah]

Can't believe no one corrected your post till now. Please, go read an aerodynamics textbook before commenting on anything technical.

Retracting flaps REDUCES the angle of attack, and extending flaps INCREASES AoA. The Angle of Attack (AoA) is the angle between the relative wind and the chord line of the wing. The chord line is the line between the leading edge and trailing edge. The trailing edge changes when the flaps are extended or retracted. When flaps are extended, the trailing edge lowers relative to the existing chord line, the chord line steepens relative to the relative wind, and the AoA increases.

Do you want to get technical? I don't think it's as simple as you make it out to be. Every time you change configuration, you also get a whole new airfoil, complete with a new critcal AOA. The camber is effectively increased with flap deployment in most cases.

I suspect lowering the flaps at a given weight, in level flight, at a given speed will increase your AOA, but also given you a greater margin to your critical AOA. This obviously comes at a price, greater drag, especially with final flaps in most planes.

Consider a regional aircraft in it's landing configuration, that gets too slow. If you retract the flaps, it WILL lower the AOA, but you probably won't have enough lift from the resulting configuration to maintain level flight. Is reducing the AOA by retracting flaps always the best course of action?

Fly Safe,

Lilah


Edit: Crossky, I don't really think you OR embpic1 were advocating retracting the flaps as a first step of stall recovery, I just think you were a little harsh on his comment. To me, he clearly implied that retracting the flaps would bring you closer (or exceed) your critical AOA if you were trying to maintain level flight.

 

[Crossky]

Do you want to get technical? I don't think it's as simple as you make it out to be. Every time you change configuration, you also get a whole new airfoil, complete with a new critcal AOA. The camber is effectively increased with flap deployment in most cases.

I suspect lowering the flaps at a given weight, in level flight, at a given speed will increase your AOA, but also given you a greater margin to your critical AOA. This obviously comes at a price, greater drag, especially with final flaps in most planes.

Consider a regional aircraft in it's landing configuration, that gets too slow. If you retract the flaps, it WILL lower the AOA, but you probably won't have enough lift from the resulting configuration to maintain level flight. Is reducing the AOA by retracting flaps always the best course of action?

Fly Safe,

Lilah


Edit: Crossky, I don't really think you OR embpic1 were advocating retracting the flaps as a first step of stall recovery, I just think you were a little harsh on his comment. To me, he clearly implied that retracting the flaps would bring you closer (or exceed) your critical AOA if you were trying to maintain level flight.

It might or might not, that depends on the airspeed and load factor/G, I suppose. If a wing is already below the stall speed for a lower flap setting than what the flaps are at, that's a nail waiting to be driven in the coffin. And I think that's what happened here. However, with the same relative wind and body angle, the AoA always decreases with a flap retraction.

I don't want to get too technical, I'm just for pure understanding and application of aerodynamics, that's all.

In this accident, it's clear that the shaker went off artificially, because of the automatic 20 kt increase in Vref speeds when wing anti-icing is on.

Sure, the critical AoA changes with a flap position change, but I don't know how much or which way. My point was the AoA immdiately increases with flap extension and immediately decreases with flap retraction. In response to a flap change, a pitch and power change will have to occur to change the AoA back toward where it was before.

The shaker activated at about 130 kts, the A/C pitched up, slowed much further, banked steeply, and flaps were retracted. All these things made the situation worse and brought the plane much closer to a wing stall. The worst thing about retracting flaps at too low a speed is that stall speed increases as flap extention decreases, of course.

I think we're speaking the same language, just vastly different dialects. Sorry if I was harsh to embpic1.