F900 CREW HAD AN NMAC IN PATTERN AND A GAR ON SHORT FINAL.

Narrative

UPON ARR INTO CLASS D AIRSPACE; TRANSITION FROM APCH AND BEING HANDED OVER TO TEB TWR; ACFT #2 RPTED '1 MI OUT' TO TEB TWR. TWR RESPONSE WAS. '1 MI OUT FROM WHERE?' ACFT #2 SAID 'ARPT.' THE TWR GAVE LNDG CLRNC TO ACFT FOR RWY 19; ACFT #2 REQUESTED RWY 24. TWR CLRED ACFT #2 TO LAND ON RWY 24. AFTER ENTERING DOWNWIND FROM CIRCLING APCH; ACFT #1 CONFIGURED FOR LNDG RWY 19 AT 1500 FT PATTERN ALT. WHILE TURNING BASE LEG AT 1500 FT; STARTING DSCNT FROM PATTERN ALT; A YELLOW TCASII TARGET WITH NO MODE S (ALT TAG) APPEARED AT THE 12 O'CLOCK POS; LESS THAN 1 MI. I MAINTAINED 1400 FT AND INCREASED RATE OF TURN. THE ACFT #2 WENT UNDERNEATH US AT 100 FT. WE RPTED AN NMAC TO TEB TWR (ACFT #1) AND CONTINUED ON VISUAL APCH TO RWY 19. WHILE ON FINAL TO RWY 19 (ACFT #1); ACFT #2 BEING ON A VERY STEEP APCH TO RWY 24; DOVE TOWARDS THE RWY INCREASING RATE OF DSCNT AND GND SPD. MONITORING CLOSURE RATES OF THE 2 ACFT ON INTERSECTING RWYS; SEPARATION DETERIORATED. IT WAS DETERMINED BY ACFT #1 THAT THERE WAS INADEQUATE SEPARATION BTWN THE 2 LNDG ACFT AND ACFT #1 INITIATED A GAR AT 50-100 FT AGL. THERE WAS NO INPUT OR COM FROM THE TWR DURING THE CONVERGENCE. MANY SEQUENTIAL EVENTS HAPPENED: 1) ACFT #2 APPARENTLY ENTERED CLASS D AIRSPACE WITHOUT PERMISSION. 2) ACFT #2 GAVE INCORRECT POS. 3) ACFT #2 WAS AT WRONG PATTERN ALT. 4) ACFT #2 HAD NO MODE S. 5) TEB TWR WAS NOT DILIGENT IN MAINTAINING SEPARATION.