Flight Sim HUD (cont.)

This is a continued question from the old boards. I already got some replies there and I have some more questions.
I’m trying to do a HUD for a flight simulator and someone told me I could do it with gluOrtho2D but that didn’t work well. Anyways, I tried doing it by having a camera location and a HUD location which was located initialy in front of the camera. Everything was fine at first, it showed what I wanted, but when the plane started to fly, the HUD didn’t fly with it (it moved, but not exactly like the plane, it moved slower)even though I did the exact same calculations for the HUD as for the plane.
The way I make the plane fly is by having roll, pitch and heading angles and using glRotate for these, and then
So in short, the problem is that the HUD is moving much slower than the plane so it doesn’t stay in the center of the screen.

Thanx in advance for any help.