B737-300 CREW; WITHOUT SPECIFIC CLRNC TO GIVE WAY TO ACFT AHEAD; CUT THEM OUT AND TAXIED FASTER THAN CONDITIONS WARRANTED.

Narrative

WE PUSHED BACK FROM GATE IN SEA AND CALLED FOR TAXI UPON COMPLETION OF THE PRE-TKOF CHKLIST. OUR INSTRUCTIONS FROM GND CTL WERE 'COMPANY X TAXI TO RWY 16L VIA TXWY B.' AS WE HEADED NORTH ON TXWY B BEHIND A COMPANY Y B737; I NOTICED A COMPANY Z B737 HAD JUST PUSHED BACK AND WAS DISCONNECTED FROM THE TUG. HE WAS ON THE RAMP ABEAM TXWY M. AS WE APCHED HIS 7 O'CLOCK POS; HE STARTED TO TURN L TOWARDS TXWY B. WE WERE ABEAM HIM AT THIS POINT. I NOTICED THIS WOULD BE A CONFLICT; SO I VEERED L FROM THE TAXI LINE ABOUT 3 FT TO ENSURE SEPARATION FROM THE 2 ACFT. WE HAD AT LEAST 30 FT WINGTIP SEPARATION AS WE PASSED; AND MY GND SPD WAS AROUND 20 KTS. AT THIS POINT; THE COMPANY Z B737 CALLED FOR TAXI AND STATED TO GND 'GND COMPANY Z -- TAXI AND I THOUGHT YOU WANTED US TO FOLLOW COMPANY Y.' THE GND CTLR REPLIED 'TAXI TO RWY 16L AND FOLLOW COMPANY. SORRY; BUT COMPANY SNUCK UP ON ME; AND I DID NOT TELL HIM TO FOLLOW YOU TO RWY 16L -- SORRY.' COMPANY Z THEN REPLIED THAT HE FELT THAT THE PASS WE MADE ON HIM WAS IN A DANGEROUS NATURE. I THEN ASKED MY FO TO ASK GND IF SHE WANTED US TO PULL OVER AND FOLLOW COMPANY Z. SHE SAID NO; AND TOLD US TO CONTINUE. SHE ALSO STATED THAT SHE FORGOT TO TELL US TO FOLLOW COMPANY Z. AT THIS POINT; WE SWITCHED TO TWR FOR TKOF. I FEEL THIS ALL COULD HAVE BEEN PREVENTED; IF GND HAD TOLD US ON INITIAL CONTACT TO FOLLOW COMPANY Z TO RWY 16L. AT NO TIME DID WE HEAR THE GND CTLR GIVE COMPANY Z TAXI INSTRUCTIONS PRIOR TO US REQUESTING TAXI. SUPPLEMENTAL INFO FROM ACN 570644: TAXI CONFLICT. FROM GATE; WE RECEIVED TAXI CLRNC FROM SEA GND TO 'TAXI TO RWY 16L.' NO OTHER INSTRUCTIONS BEYOND THAT. ON TXWY B HDG N; WE WERE ABOUT 300 FT BEHIND A COMPANY Y B737; ALSO TAXIING N ON TXWY B. THERE WAS A COMPANY Z B737 THAT HAD ALREADY BEEN PUSHED BACK AND WAS ABOUT 150 FT E OF TXWY B FACING N. THE COMPANY Z JET APPEARED TO BE WAITING FOR TAXI CLRNC AND WAS MOVING VERY SLOWLY PARALLEL TO; BUT SLIGHTLY TOWARDS TXWY B. WE WERE TAXIING FASTER THAN COMPANY Y AND CLOSE TO 50 FT IN TRAIL WHEN AT COMPANY Z 7 O'CLOCK POS. AS WE TAXIED IN BEHIND COMPANY Y; GND CALLED COMPANY Z AND APOLOGIZED FOR LETTING US 'SNEAK IN.' COMPANY Z STATED THAT WE WERE TAXIING FAST AND HAD 'SCARED HIM.' I CALLED GND AND ASKED IF SHE WOULD LIKE US TO PULL OVER TO THE SIDE AND LET COMPANY Z PASS. GND STATED WE WERE OK TO CONTINUE. COMPANY Z CAME BACK AND STATED 'THE DANGER HAS ALREADY PASSED.' I BELIEVE COMPANY Z HAD BEEN GIVEN TAXI CLRNC TO FOLLOW COMPANY Y; BUT WE HADN'T HEARD IT. I THINK GND CTL THOUGHT COMPANY Z WOULD HAVE PLENTY OF TIME TO GET BEHIND COMPANY Y WITHOUT HAVING TO WORRY ABOUT US BEING A CONFLICT. SINCE COMPANY Y WAS TAXIING SO SLOWLY; WE WERE ABLE TO CLOSE THE DISTANCE AND CONFUSION RESULTED. I THOUGHT WE WERE DOING COMPANY Z A FAVOR BY EXPEDITING OUR TAXI; SO WHEN HE CALLED FOR TAXI; WE WOULD BE IN A POS BEHIND COMPANY Y; I WAS SCANNING THE WINGTIPS AS WE PASSED COMPANY Z. WE HAD 30-50 FT WINGTIP SEPARATION. COMPANY Z WAS MOVING AT 2-4 KTS; MOSTLY PARALLEL TO TXWY B. I DID NOT FEEL THERE WAS ANY THREAT OF A CONFLICT. GND DID NOT INFORM COMPANY Z WE WERE BEHIND COMPANY Y; AND WE DID NOT KNOW COMPANY Z WAS CLRED TO TAXI IN SEQUENCE BEHIND COMPANY Y. IN THE FUTURE; I WILL QUESTION GND IF THERE IS ANY DOUBT ABOUT A TAXI SEQUENCE.