Question: I was studying for icing and a tailplane stall. I have looked up some internet pages and instrument flying handbook, and found the procedure below.

1. raise flaps to the previous setting. (To reduce down wash from the main wing so that reducing negative angle of attack of the tail and break the stall)
2. apply nose up elevator pressure (I don't get it. The nose up pressure will make the elevator to go up and wouldn't this increase the negative angle of attack and worsen the stall?)
3. do not increase airspeed unless it is necessary to avoid a wing stall. (Why shouldn't we increase airspeed?)

So now I'm trying to understand the reason why should a pilot do such actions. Can you help me out?

Answer: 
There was a NASA report on the [NASA/FAA Tailplane Icing Program Overview](http://ntrs.nasa.gov/search.jsp?R=19990019485&hterms=19990019485&qs=Ntk%3DDocument-ID%26Ntt%3D19990019485%26N%3D0), which covers the points raised by you. It lists certain actions that can be done to recover from a tail plane stall:

> 
> When the full tail stall was experienced during the power transition, the stall recovery procedure was:
> 
> 
> • Reduce thrust (may be airplane specific)
> 
> 
> • Pull back on yoke/ increase $\alpha$
> 
> 
> • Raise flaps
> 
> 
> 

* Raise flaps to previous setting

This is done mainly to undo the changes that caused the stall in the first place (reducing thrust is also done for this reason). The report says,

> 
> The major lesson learned to recover from a tail stall was to undo what was
> just done to cause the event.
> 
> 
> 

* Apply nose up elevator pressure

Basically you are pulling back on the yoke to increase the tail download so that the aircraft nose-down pitching moment is countered. From the report:

> 
> Pulling back on the yoke increased the camber of the tailplane, which provided enough tail download to counteract the nose-down pitching moment and increase the $\alpha\_{tail}$
> 
> 
> 

This sounds counterintutive as the conventional tail produces force in the direction opposite to the main wing. The report notes:

> 
> It was noted that this tail stall recovery procedure is opposite of the recovery from a wing stall. The reason for the difference is the location of the flow separation. In a wing stall, the flow separates from the upper surface of the wing, therefore reattachment is made by decreasing the wing $\alpha$. In a tail stall event, the flow separates from the lower surface of the tail and requires a positive increase in tail to reattach the flow.
> 
> 
> 

* Do not increase airspeed unless it is necessary to avoid a wing stall

The aircraft is already at a nose down attitude. Increasing speed will further excabarate the situation, which may put the corrective action beyond the capability of the tailplane.
I have a theory on applying the backstick on a tail stall induced while lowering the flaps. OP’s comment:

> 
> apply nose up elevator pressure (I don't get it. The nose up pressure will make the elevator to go up and wouldn't this increase the negative angle of attack and worsen the stall?)
> 
> 
> 

If the tail stalls, then the nose pitches forward. The center of rotation is about somewhere near the wing and CG, well forward of the tail. So the tail instantly sees a step increase in AOA, to well beyond the stall AOA. Probably really high AOA. The aircraft develops inertia in pitch too.

At this point, you are doing triage while you lower the flaps and undo what you did. While you’re not getting much lift (downward) from the tail, it is resisting the forward pitch with drag. Letting the stick or yoke come forward would dump this pitch resisting force, and the aircraft would go right over its nose before the flaps could raise.

There’s my theory.