ACR X POTENTIAL LTSS FROM ACR Y. OPDEV POTENTIAL SYS ERROR.

Narrative

ACR X ARRIVED IN DALLAS (DFW) ON TIME; WERE VECTORED TO A VISUAL APCH RWY 18R. DURING OUR LNDG ROLL THE TWR CTLR TOLD US TO TURN L AT THE APCHING HIGH SPD; USE TAXIWAY 27; CLRED TO CROSS RWY 18L; CONTACT GND .8! THE FO ROGERED AND READ IT BACK! WE WEREN'T EVEN INTO TAXIWAY 27 YET; WHEN I HEARD THE TWR CLR ACR Y FOR TKOF RWY 18L. WITH THIS I LOOK UPFIELD TO SEE IF ACR Y WAS STILL ON A TAXIWAY AND NOT READY TO GO; MAYBE THE TWR WAS JUST GETTING AHEAD. MUCH TO MY DISBELIEF THERE WAS ACR Y LIGHTS ON AND BLACK SMOKE POURING OUT THE BACK OF BOTH ENGS; HE WAS ON HIS WAY! I BROUGHT MY ACFT TO AN ABRUPT STOP ON TAXIWAY 27 AND WAITED FOR ACR Y TO GO BY. AFTERWARDS; I TOLD THE TWR WE WERE HOLDING SHORT RWY 18L ON 27 DUE TO THE FACT THAT WE HADN'T GOT ACROSS BEFORE ACR Y ROGERED. I DON'T THINK HE REALIZED WHAT HAD HAPPENED. THE WX WAS GOOD. I WAS LISTENING CLOSELY TO THE RADIO THIS DAY; HOWEVER; HAD THERE BEEN FOG; RAIN; ETC; OR HAD WE BEEN DOING OUR AFTER LNDG CHKLIST AT THAT MOMENT; THE POTENTIAL FOR DISASTER WAS THERE.