Interlock for a drill rig and method for operating a drill rig

An interlock for a drill rig, comprising:

• a drawworks comprising a drum operably connected to a drive system and a brake;
• a cable that extends from said drum of said drawworks to a block and tackle arrangement holding a traveling block, wherein operation of said drawworks causes said drum to release or retract said cable;
• a tong;
• a means for sensing a position of said tong;
• an interlock signal generated by said means for sensing said position of said tong, wherein said interlock signal is reflective of said position of said tong;
• and
• a lock operably connected to said drawworks, wherein said lock receives said interlock signal and disables operation of said drawworks if said interlock signal meets a predetermined criterion, wherein said predetermined criterion indicates that the tong has been at least partially extended.

A method for operating a drill rig, comprising:

• operating a drawworks to raise and lower a drill string;
• operating a tong;
• sensing a position of the tong;
• generating an interlock signal that reflects the position of the tong;
• and disabling the drawworks if said interlock signal meets a predetermined criterion, wherein said predetermined criterion indicates that the tong has been at least partially extended.