Translate Cockpit view backward issue

I have been trying to set up cockpit camera views to tour the inside of an aircraft. All the translate camera commands seem to work with the exception of translate camera backwards. I set Alt + Cntl + B and the camera will only go back to the pilot seat. Tried other key combinations and same effect. The camera won’t move to the back of the aircraft. What am I missing? Thanks in advance for any help.