DublinFlyer

See now this just scares me. And there is really nothing we can do about it once it gets on there. Alright so let me make sure this is right - Bombardier said it would be possible to accumulate icing on the tail.... but it just wouldn't affect the characteristics of flight? God I feel stupid because I just don't get that.

bubi352

Let's put it another way. NASA did several test flights on tail stalls and proper recovery techniques. I remember the test pilot saying how abrupt the pitch went down. It took if I remember correctly 300 feet for the recovery (don't quote me on this). This being said, they knew it was coming and were prepared for it.

There is nothing like aerobatics to prepare you for an upset or put you in a certain comfort zone. How many pilots in here have even flown once inverted?

KC10 FATboy

Bubi352, you make a good point. All the military pilots would have flown aerobatics, but I would say that very few civilian pilots have. However, they should have been given upset recovery training in the sim. Yes, I know its not the same, but, I guess thats the best you can do without spending $1-2 million dollars per pilot for pilot training. Only uncle sam can afford such nice things.

Your post made me flashback to my first ride in UPT. I was a T-34 guy at Whiting and the instructor flew me to the area and said, "are you ready for the aircraft? You've got it in 3, 2, 1!!!" Suddenly the aircraft departed controlled flight. He had set the trim in all three axis to full travel in one direction and had been holding it until he gave me the aircraft. Good times.

-Fatty

JoeyMeatballs

Aircraft Icing Training -Great Website-

Aircraft Icing Training - A Pilot's Guide to In-Flight Icing

Lowlevel

This is the dvd that I talked about in a previous post

http://www.sportys.com/acb/showdetl....roduct_id=6429

Cheap and it has an interesting Tailplane icing section

I bought it back when I flew Part 135 cargo into ice all the time in NY and PA. It is worth the money.

The Duke

Yes, this is good stuff...I think someone also mentioned that the NASA video resulted in an altitude loss of 300', this after they were anticipating the tail stall as this was what they were specifically testing. In the video, the flaps are immediately returned to previous setting and strong back pressure was applied to prevent further alt. loss.

Maybe this question has already been addressed and I missed it, but does a tail stall result in a stick shaker and stick pusher in the Q400? I doubt it because pitching down would exacerbate the tail stall, but just ignorant and curious.

I know the Dash 8 Q200 will sense a main wing stall and will activate the shaker. It does not have a pusher, though.

bubi352

I have not flown the Q400 but most transport aircraft stall warning device are based on their AOA indicator not actual induced airflow separation. Makes it a lot harder to detect a potential tail stall. Based on NASA, I think it comes back to basic stick and rudder recognition but this is better said than done.

Blue Side Up

In the interest of furthering some more discussion and clarifying some questions, the following is adapted from the Flight Safety Q400 Flight Crew Operating Manual (Jan 2008)

On the Q400 the stick shakers (L & R) are controlled through their respective Stall Protection Modules (SPM). The SPM's uses the following parameters to calculate when the aircraft is near stall and activate the shaker:
-Angle of attack data (from heated AOA vanes)
-Flap position
-Mach number
-Engine torque
-REF SPEEDS switch position

The single Stick Pusher uses data from both SPM's and averages the AOA data. It uses all the parameters from above plus the Power Lever and Condition Lever Angles to activate the pusher.

An active Stick Shaker will cancel all GPWS "Pull Up" audible alerts.

The Stall Protection System is not fully operable below 200 ft. AGL (not sure if fully inhibited or not)

The pusher clutch can be manually overridden by pulling approx. 80 lbs. on the control column.

The Pusher can be shutoff by pressing a latchable switch on the glare shield.

Killer51883

fat boy---I am just thinking that with ice the actual stall speed could easily be greater than your 1.3vso/ref speed. Using your 100kts vso and a ref of 130 with a v-approach of ref+10 or 140 in an accelerated condition with ice the stall speed could be very very close almost resulting in a coffin corner type situation. I would like to add that I am by far an aerodynamic expert so this is all just a random theory I am coming up with.

The comment about aeroabatics is very true. Thankfully my college had a very good aerobatic trainer that was used to teach upset recovery and basic aerobatics in. The flying that has exposed me to taught some invaluable lessons wich i reccomend every pilot should make a chance to get.

Also I remember while I was training in a glider that you could tail stall the glider rather easily. Maybe some one with more glider time than I have could comment on that.

captain152

I was thinking the exact same thing about a coffin corner situation.

Coffin corner is always talked about up at the higher altitudes, but I think that very soon there is going to be 2 coffin corners.

In this situation, the crew described what they called "significant" ice build up on the wings (not uncommon coming in and out of BUF during winter I will add). If this were true it would have increased stall speed by a good margin. And if they did in fact encounter a tail stall, in which the recovery procedure is to pitch up, reduce power, and retract the flaps ... well if you've got ice on your wings, that's just about the LAST thing you're going to want to do because it's going to flat out kill what little airspeed you have left when you're slowing for approach and landing. And, just from watching the NASA Tailstall icing video, you've gotta pull back on the yoke pretty damn hard to get that plane to come back up ... in doing so, the airplane could have easily lost more than enough airspeed and went directly from one stall to another. And we ALL know the recovery procedures for a normal wing stall ... we've had that beaten into our heads from day 3 of Private.

In the CNN news broadcast the people said they heard the engines making unusual sounds. My guess is that if they did go from one stall to another, knowing Marvin the way I did, and it being his leg, he had damn near (if not completely) fire-walled the power levers and was causing the engines to basically scream for power and doing everything he could to keep that aircraft in the air. Unfortunately, they were at a very low altitude and had almost zero time to react.

Again, if this speculation holds true ... I think we just found a second definition of Coffin Corner.

I would like to add on a happy note that this is one of the BEST threads hands down that I have ever read here. Thank EVERYONE for their contributions.

Godspeed to 3407, RIP. Best wishes to their families