Interesting Stall Information
 

I'm not speculating on the cause of yesterdays crash but i started reading up on different scenerios to try and learn. I was completely shocked at what i read about tail stalls. i felt i should pass this information on to my fellow pilots as i was completely unaware of the effects of a tail stall and had i been put in this kind of situation the outcome would have been dire. hopefully spreading a little knowledge will help us feel better... again im not playing NTSB, i just thought this information would be useful to some.


In this scenario, with the added airspeed on approach, a tail stall is more likely than a wing stall. If there is any ice on the wing, there may be far more on the horizontal stabilizer -- and the pilot may not know ice is building until the airplane's configuration is changed. On approach, with flaps extended and the airplane close to the ground and close to its performance limits, recovery is very difficult.

Even a small amount of ice on the leading edges can cause flow separation and a sudden change in attitude when different inputs are applied, says Rieke. It's critically important to remember that what works for wing stall may intensify a tail stall. In a wing stall recovery, the pilot relaxes back-pressure or pushes the yoke forward to reduce the angle of attack and increase airspeed and regain control.

Responses associated with tail stall recovery are counterintuitive to what student pilots are taught. The stall symptoms are similar, but the recovery is absolutely different: Pull the yoke back (which might take great force); raise the flaps, if lowered; and reduce or be judicious with the power. The NASA pilots say a tail stall talks to you through the yoke; a wing stall you feel in the seat of your pants.

Tail stalls almost always occur with flap extension or at the high speed limit for flap extension.
And a tail stall can sneak up on you. Icing doesn't always show up on the windscreen. If you feel buffet in the yoke and a lightening in the controls that leads to PIO, you most likely have tailplane ice. "It's possible to have very little ice on the wing and significant accumulation on the horizontal tail," says Rieke. "Any ice will affect how the airplane flies; to what degree is unknown."

tzadik -

Thanks for posting this information. I'm not familiar with Tail Stall and I have very little experience flying in moderate or worse icing conditions; so you have acheived your objective. You've educated at least one pilot out there.

USMCFLYR

I think this is an interesting topic, and lets try and keep it away from Colgan 3407 for right now until we have more details. I'm all up for learning new things, so lets talk about this.



I can say I didn't know much about icing (or tail stalls), other than what I was taught in the books during my flight training. Growing up in the south I never experienced icing until I actually started flying the jet at work. Since then I've gone back and read up on more information, and of course I learn the most while actually experiencing it.

One thing that bothers me about the CRJ is the fact there is no anti-ice on the tail. Bombardier says it's aerodynamically impossible to get icing on the tail, and that may be true to an extent, but I'm not 100% confident in it. I guarantee if you put me in tail icing right now I probably wouldn't know what was going on. I'd really like to know more (have always wanted to) about that sort of icing, what effects it has, how you can tell, and what you need to do about it.

Like I said - interesting topic. I try and learn as much as I can, but this is something I'm not very familiar with at all. I know as much as most people do about wing stalls, but not tail stalls.

the worst thing about the Tail Stall is the recovery procedure is the complete opposite of that of a wing stall, and anytime the nose points down we have been DRILLED to reduce the angle of attack and MAX POWER.........

I flew Beech 1900's for the USAF. While I was there, an air directive came out about tail icing. I believe this was in response to the ATR crash that was holding for approach in Chicago. There was also a video we watched from the FAA which was created by NASA.

Essentially what TZADIK posted is spot on. For T-Tail aircraft, due to the flow of air over the wing which effects the flow of air over the T-Tail, this can lead to significant ice build up on the T-Tail. In fact, if you see a little ice on the wings or cockpit, you already have TOO MUCH ice on the tail. NASA showed video of the wing and T-Tail of a plane that was flown into heavy icing. Even though the wing had maybe an inch of ice on the leading edge, the tail had 4 times as much! They also showed recovery techniques which are the same as given above and are opposite for a normal wing stall recovery.

This air directive changed how often and when to blow the boots on the Beech 1900 and the procedure was changed in our manuals.

I have to admit, I am kind of surprised that this is something new for the guys who are flying T-tails. If you don't know it.

-Fatty

you are reducing angle of attack when you pull up during a tail stall, just on the tail.

Anybody watching the NTSB briefing going on right now? Initial data analysis is making this thread sound awfully pertinent.

Flaps 15 selected 40 seconds prior to end of recording, with "severe" pitch and roll excursions immediately thereafter.

Just watched the briefing, thread sounds very pertinent. Sounds like whatever occurred happened really fast. 40 seconds is pretty darn quick.

yeah I understand that............ I meant reduce the AOA of the WING, not the tail

and i thought we were going to keep the speculation out of this thread!!! Well any way nice post Tzadik I appreciate the info.