Today's topics answered by Peter Cox, who is a 737-800 Captain for a major UK leisure airline are: Dangerous airports, do they really exist? The emergency oxygen, where does it come from and how long does it last? I’ve seen engineers putting silver masking tape on a plane, what is this, is it safe? Can parts of the plane be broken but still be allowed to fly? Why during landing does it sound like the engines are revving up and down continuously? What is the shudder/shaking noise when the wheels retract on some aircraft? How does the wing remain capable of keeping the aircraft in the air when it dismantles itself for landing (flaps fully extended and passengers being able to see through the wing)?