1.   Boeing has been working on a secure cockpit door for the past few years.

2.   Byers said he also was considering ordering airlines to protect pilots by installing secure cockpit doors to isolate the flight deck from the rest of the cabin.

3.   Byers said he was also considering ordering airlines to protect pilots by installing secure cockpit doors to isolate the flight deck from the rest of the cabin.

4.   The union also is exploring new standards for secure cockpit doors to protect the flight crew against attacks.