INSTRUCTOR PLT OF A C172 TRAINING FLT DIRECTED TRAINEE TO TURN BASE LEG WITHOUT FIRST BEING TOLD TO DO SO BY TWR CAUSING A PIPER NAVAJO; PA31-350; TO BREAK OFF FINAL AT THE DIRECTION OF THE TWR CTLR.

Narrative

I WAS CONDUCTING PLT TRAINING IN THE PATTERN AT NORTH LAS VEGAS; NV; AT APPROX XA00 LCL TIME. WE WERE IN THE DOWNWIND (L) FOR RWY 7 AND HAD NOT BEEN SEQUENCED TO THE ARPT OR TOLD TO EXTEND DOWNWIND (TO MY KNOWLEDGE) AND I HAD NOT ACKNOWLEDGED ANY INSTRUCTIONS; SO WE TURNED A NORMAL L BASE. UPON TURNING BASE MY STUDENT SAW THE PIPER NAVAJO AT THE SAME TIME THE TWR CTLR TOLD THE NAVAJO TO BREAK OFF THE APCH. WE CONTINUED ON THE APCH AND DID A TOUCH AND GO AND CONTINUED IN THE PATTERN TO A FULL STOP LNDG. AFTER WE EXITED THE RWY AND CONTACTED GND CTL WE WERE TOLD TO COPY A TELEPHONE NUMBER AND CALL THE TWR AFTER PARKING; WHICH I DID. THE PROB AROSE DUE TO THE FACT THAT I DID NOT KNOW THAT THE PIPER NAVAJO CHIEFTAIN WAS ON FINAL APCH FOR RWY 7. PERHAPS IT WAS DUE TO THE FACT I WAS GIVING INSTRUCTION AND DID NOT HAVE A PROPER LEVEL OF SITUATIONAL AWARENESS; HOWEVER I WAS NOT SEQUENCED OR TOLD TO EXTEND DOWNWIND (OR AT LEAST I NEVER ACKNOWLEDGED ANY SUCH INSTRUCTIONS). THERE ARE MANY CONTRIBUTING FACTORS WHICH LED TO THIS SIT; BUT I FEEL THE BIGGEST ONE IS HOW BUSY THIS ARPT HAS BECOME OVER THE LAST SEVERAL YRS -- DUE TO THE FACT THAT MCCARREN INTL ARPT HAS BECOME SO BUSY; WHICH HAS CAUSED RECENT CHANGES TO THE ARR PROCS INTO THIS ARPT. THESE CHANGES HAVE BEEN VERY DISRUPTING TO THE TFC FLOW IN AND OUT OF THIS ARPT. I FEEL THAT THE SIT NEEDS TO BE LOOKED AT BEFORE WE HAVE A MIDAIR COLLISION AT THIS ARPT.