As a result of this

This thread started

there was a landing accident in one of the passenger aircraft where in spite of losing lateral control, pilots tried to land with alternating throttle, succeeded partly, another freighter was hit by a missile they succeeded completely. as a result PCA came about.

Propulsion-Controlled Aircraft (PCA) system. Utilizing the pre-existing auto-throttle and engine-pressure-ratio trim controls of the airplane, the PCA system provides pitch and roll control for landing an airplane safely without using aerodynamic control surfaces that have ceased to function because of a primary-flight- control-system failure. The installation of the PCA does not entail any changes in pre-existing engine hardware or software, pilot controls the aircraft as if he is applying conventional controlling inputs, the FBW (Fly By Wire) takes care of the rest.

There is good in everything

This reminds me of something I had read and was amazed at :

http://en.wikipedia.org/wiki/United_Airlines_Flight_232

Never new you could fly these big ones and some how land with no hydraulics and control surfaces... just using differential thrust.

precisely, united 232 that's what i am talking about.

here is the real landing video



Thanks to PCA it is the thing of the past

Even in many cases pilots were successful landing aircraft in one piece after loosing all control surfaces
for eg:- http://en.wikipedia.org/wiki/American_Airlines_Flight_96
             http://www.airsafe.com/events/models/boeing.htm  (look at china airlines 1982)
our captain says its purely luck and weather condition! to land a aircraft using PCA ,
first thing throttle response is very slow in jetengined aircraft to counteract for sudden changes in attitude at low altitudes and low speeds!
second thing slow response to changing winds (in other words "Wind Shear")

wind shear ? even fighter aircraft have been lost due wind shear, obviously with the controls gone you will have to divert to an airfield where the weather is fairly ok. even then CAT (Clear Air Turbulence) will be problem. On the simulator though PCA, in good weather condition is not too difficult.

thats what im saying in ,good weather conditions many of them have made it ! but at last, "wind and weather" will  never be at your favour! aircraft approaching using PCA even 10knts mild crosswind will be catastrophic!!!!!!! thats what happened to united 232 !!!
in simulator everything is possible ! but coming to practical everthing shifts approx 180 deg!( emergency conditons)

totally, i remember one such occasion in my life. CAT outta nowhere

On the model side, this is already being done, where you have those two motors which you control to turn and gain or loose altitude.

@flyingboxcar 
its used in small foamy aircraft! (as far as i know)
have u seen in any bigger balsa or composite models?

Praveen, do not know about models (balsa or composite) but I think A/c's like, Su 30, Harrier, YF 22 etc do utilize thrust vectoring apart from conventional control surfaces.
In my opinion these would we fit to be classified as propulsion control aircraft   

if i remember correctly its "Thrust Vectoring" not propulsion control ,in thrust vectoring u vary the angle of thrust , not amount of thrust!

But is it not that you are controlling the aircraft by manouvering the propulsion plant. If you see a Harrier landing vertically not only is the thrust angle changed but also the amount of thrust.
And going a step beyond, there is a saying in full scale circles, "Its the throttle which controls the alltitude and elevator the attitude". So by that maxim, its the mode of propulsion which is controlling the aircraft in conjugation with the control surfaces, which in a way takes us back to my post number 7 about small foamys :-)