SMT X LNDG ON OCCUPIED RWY HAD LTSS FROM SMT Y. SYS ERROR.

Narrative

I OBSERVED THE TWR CTLR ALLOW 2 ACFT TO OPERATE ON THE RWY AT THE SAME TIME WITH LESS THAN PRESCRIBED RWY SEPARATION. THE CTLR HAD SMT X ON FINAL APPROX 2 MI OUT AND PUT SMT Y INTO POS AND HOLD; PENDING A PREVIOUS ARR CLRING DOWN FIELD. HE THEN ANSWERED ANOTHER ACFT INSTEAD OF CLRING SMT Y FOR TKOF. WHEN HE FINALLY CLRED SMT Y FOR TKOF; HE FAILED TO USE THE PHRASE 'IMMEDIATE' AND WAS VERY NONCHALANT IN HIS DEMEANOR OVER THE RADIO; EVEN THOUGH BOTH THE CAB COORDINATOR AND THE TWR SUPVR WERE CUING HIM TO REACT IN A MORE EMPHATIC MANNER. THERE WERE APPROX 3500 FT BTWN THE TWO ACFT AND THE PRECEDING SMT Y DEP HAD NOT ROTATED WHEN SMT X FLARED OVER THE RWY NUMBERS. 4500 FT IS THE REQUIRED DISTANCE; AND THE PRECEDING DEP MUST BE AIRBORNE. AS STATED BEFORE; THE SUPVR OBSERVED THE ENTIRE OP AND TREATED IT AS IT WAS A JOKING MATTER. I WOULD NOT HAVE SUBMITTED THIS RPT HAD THIS BEEN A FIRST OCCURRENCE ON BEHALF OF EITHER THE CTLR OR THE SUPVR. IN FACT; THIS IS THE THIRD SIMILAR INCIDENT IN 6 MONTHS WITH THIS PARTICULAR CTLR; AND THE SUPVR HAS TOO MANY DEFICIENCIES TO GO INTO THIS RPT.