TRAINING IN PROGRESS; TRAINEE HAS AN SMA DEPARTING AND ANOTHER SMA LNDG RESULTING IN LTSS.

Narrative

AT THE TIME I WAS TRAINING A TRAINEE WITH OVER 40 HRS OF TRAINING. IT WAS NOT VERY BUSY; THE SIT WAS NOT COMPLEX; AND THE TRAINEE HAD DEMONSTRATED PREVIOUS ABILITY TO HANDLE SIMILAR SITS WITHOUT ANY DIFFICULTY. SMA X; WITH A STUDENT PLT AND AN INSTRUCTOR; WAS PERFORMING TOUCH- AND-GOES IN L TFC TO RWY 29. SMA X CALLED READY TO GO; FULL LENGTH RWY 29. SMA Y WAS GIVEN CLRNC TO TAXI INTO POS AND HOLD. AS THE TRAINER; I LOOKED UP AND SAW THAT SMA X; WHO HAD BEEN CLRED FOR THE TOUCH-AND-GO; WAS STILL IN THE DOWNWIND. I THEN LOOKED AWAY BELIEVING THAT THE SIT WAS WELL IN HAND. THE NEXT THING I KNEW; THE TRAINEE CALLED MY NAME; THE TONE INDICATING THAT SOMETHING WAS WRONG. SMA Y WAS GIVEN TKOF CLRNC AND SMA X WAS FLYING OVER THE SMA Y TO THE DISPLACED LNDG THRESHOLD OF RWY 29 IN A STEEP DSCNT. THE TRAINEE THEN IMMEDIATELY TOLD SMA Y TO CANCEL TKOF INSTRUCTIONS. I THEN INFORMED THE TRAINEE THAT THE SMA X HAS TO BE SENT AROUND. THE TRAINEE WHO HAD DONE SUCH AN EXEMPLARY JOB OF CANCELLING SMA Y'S TKOF CLRNC NOW EITHER FROZE OR SAW THAT THERE WAS NO CHANCE OF THE 2 ACFT COLLIDING AND DID NOTHING. HOWEVER; AS SOON AS THE SMA X WAS OVER SMA Y AND PUT HIS WHEELS ON THE RWY; AN OPERROR HAD OCCURRED. AS THE TRAINER; I ALLOWED MYSELF TO BE LESS THAN FULLY VIGILANT OF WHAT WAS GOING ON AND LOOKED AWAY; CONFIDENT THAT THE TRAINEE HAD EVERYTHING WELL IN HAND. MY TONE NEVER IMPLIED HOW IMPORTANT IT WAS FOR THE TRAINEE TO SEND THE ACFT AROUND. MY CALM MANNER PROBABLY RELAXED THE TRAINEE TO THE POINT WHERE THERE DID NOT SEEM TO BE AN URGENT NEED TO SEND THE SMA X AROUND. AS A TRAINER; THIS INCIDENT HAS TAUGHT ME NEVER TO TAKE ANYTHING FOR GRANTED. UNTIL A TRAINEE BECOMES CERTIFIED ON A POS; THAT TRAINEE IS TO BE WATCHED VIGILANTLY; EVEN IF THEY DEMONSTRATED COMPETENCE IN SIMILAR OR EVEN LESS COMPLEX SITS. MAY WE ALL LEARN FROM OUR MISTAKES.