B757-200 FO FAILS TO ENGAGE HEADING SELECT WHEN ISSUED VECTORS AND ALT CLB BY ZBW RESULTING IN A ZBW CHALLENGE AND TFC PASSING AT SAME ALT AND 5 MI.

Narrative

WHILE CLBING THROUGH APPROX 13000 FT MSL ENRTE DIRECT BAF VOR; WE WERE GIVEN INSTRUCTIONS TO CLB TO FL230 AND TURN L TO HEADING OF 280 DEGS. I PUT BOTH NUMBERS INTO THEIR RESPECTIVE POS IN THE MODE CTL PANEL; BUT FAILED TO IMMEDIATELY SELECT 'HEADING SELECT' ON THE HEADING SWITCH. CONSEQUENTLY; THE AIRPLANE CONTINUED DIRECT BAF VOR. APCHING APPROX 17000 FT MSL; THE CTLR ASKED IF WE WERE HEADING 280 DEGS. AT THAT TIME I SELECTED 'HEADING SELECT;' INITIATED THE TURN; AND OBSERVED ON TCASII AN ACFT AT APPROX 4 O'CLOCK POS AND 5 MI; 1600 FT MSL BELOW OUR ALT. I'M NOT CERTAIN IF THE TFC I OBSERVED WAS THE PROXIMATE TFC WHICH NECESSITATED THE VECTOR; OR IF THAT TFC AT ANY POINT DREW CLOSER THAN WHEN I OBSERVED IT ON TCASII. BEFORE REACHING A HEADING OF 280 DEGS; CTR DIRECTED US TO PROCEED DIRECT BAF VOR. THE ERROR WAS CAUSED BY MY FAILURE TO REMEMBER TO PUSH THE 'HEADING SELECT' SWITCH AFTER DIALING IN THE HEADING; AND MY FOLLOW-ON FAILURE TO VERIFY THAT 'HEADING SELECT' WAS INDICATED ON THE ATTITUDE DIRECTION INDICATOR; VERIFYING THE AIRPLANE WAS DOING WHAT I WANTED IT TO DO. THE MOST APPARENT SOLUTION IS TO EXERCISE THE DISCIPLINE TO ALWAYS CHK THE EXPECTED RESULT OF AN INPUT TO THE AIRPLANE'S AUTOMATION. SUPPLEMENTAL INFO FROM ACN 583577: THE HEADING WAS NOW SELECTED. CTR CALLED OUR TFC AT OUR CURRENT ALT; 2 O'CLOCK POS AND 5 MI. WE DID NOT SEE IT. MY PARTNER MADE A PROCEDURAL ERROR IN THAT HE DID NOT ACTIVATE THE 'HEADING' MODE. I ALSO FAILED TO BACK HIM UP TO CONFIRM THE ACTIVATION. OUR AIRLINE HAS DONE A GOOD JOB OF TRAINING ITS PLTS TO 'DOUBLE POINT' AT THE ALT AND HEADING WINDOWS WHEN SET. WE NEED TO ALSO ENSURE THAT THE ACFT DOES WHAT WE THINK WE TOLD IT TO DO.