The Duh in Aerodynamics
An airliner on departure, climb, cruise, descent, approach and landing is like a symphony orchestra, with all the components working in concert. The conductor can be the FMS, Fright Management System, or the aircraft commander.
It's all seamless and symphonic until a component hits a sour note. Then you really see the contribution of the other components and what is driving them.
It's basic to conventional airplane dynamics, as taught in Langewieche's "Stick and Rudder" and hundreds of other instructional manuals:
Pitch controls airspeed.
Power controls altitude.
The A330 Flight test accident in 1994 uncovered the flaw in Airbus logic. The plane was on autopilot in Altitude Capture mode when the pilot pulled the power on one engine. The AP responded to lack of power by pulling the pitch up to over 30 degrees. Instead, it should have kept the pitch at desired speed, and told the pilot, "We can't do that."
The TK951 B737 approach accident at AMS in 2007 revealed the same flaw. An undetected erroneous input to the A/T caused it to go to Flight Idle. The autopilot tried to stay on Glideslope by pulling the nose up and trimming to lower speed to make up for lack of power. Instead, it should have kept the desired speed, and let the plane sink below glidepath. If the pilot hadn't caught that, he would have heard, "TOO LOW! GLIDESLOPE." Firewalling the throttles would have stopped the sink, and not have caused such a pitchup, as the elevator would still have been trimmed for the correct speed. The pilot could have intentionally traded some airspeed for altitude, and without fighting full aft trim.
How does this apply to 447? We'll see. Trying to control altitude with pitch is a loser, regardless.