OPERATOR ERROR BTWN ACR X AND ACR Y.

Narrative

ACR X (MD-11) WAS CONFIGURED IN FINAL 35 DEG FLAP AND GEAR DOWN AT THE FAF ON ILS RWY 06. THE CREW COMPLETED ALL CHKLISTS WITH OPS NORMAL. A LNDG CLRNC HAD NOT BEEN GIVEN AT ABOUT 7 MI OUT. ACR Y (B747) HAD BEEN GIVEN A CLRNC TO TKOF DURING THE APCH. AS ACR X PASSED ABOUT 800- 600 FT A GAR WAS CONSIDERED BY CREW; AS ACR Y WAS STILL ON THE RWY. A GAR WAS NOT MADE FOR CONCERN OF A POSSIBLE MID-AIR WITH ACR Y. TWR INSTRUCTED ACR X TO CONTINUE THE APCH. I ASKED TWR IF WE WERE CLRED TO LAND YET. ON SHORT FINAL TWR CLRED ACR X TO LAND. ACR Y WAS WAY DOWN THE RWY AND SHOULD HAVE ROTATED. ACR X AGAIN CONSIDERED A GAR BUT CREW WAS CONCERNED OF HITTING ACR Y AS THEY WOULD BE FLYING. ACR X TOUCHED DOWN. RIGHT AFTER TOUCH DOWN ACR Y CALLED A REJECT. TWR INSTRUCTED ACR X TO GAR BUT FLT WAS COMMITTED TO STOP. BOTH PLTS APPLIED MAX BRAKES AND REVERSE THRUST. A REAR -END COLLISION WAS AVOIDED WITH BOTH ACFT ON THE SAME RWY. TWR CTLR APOLOGIZED TO FLT AS ACFT CLRED RWY. I BELIEVE THIS INCIDENT WAS CAUSED BY VERY POOR TWR MGMNT AS THIS WA NOT A BUSY TIME AT THE ARPT.