Narrative:

On taxi-out, I was running the 'taxi' and 'before takeoff' checklists. Some of which required challenge and response, and others just to verbalize with a response. The captain did not have a headset and was using just one earpiece. Our instructions from the ground controller were to 'taxi to runway 21 via bravo and bravo 6 and you will back taxi on runway 21.' this was due to another aircraft that was blocking access to runway 21 on bravo as he was waiting for a flow control clearance. I understood this as not a clearance to taxi on to the active runway. As I continued to run the checklists, I was distracted by the fact that the captain was not wearing a headset with a microphone. I was wearing one with the left ear uncovered. This made communication extremely difficult and when I verified the instructions with him, he nodded yes. My concerns about this lack of a headset and difficult communication were vocalized to the captain prior to his incident on the trip. While completing the checks, I looked out and noticed the captain was crossing the hold short line on B6. I immediately told him to 'stop, we must call tower first!' he stopped, and stated that no we did not need to call them. At the next moment, ground called and instructed us to do just that. I contacted them and they then cleared us to 'back taxi on runway 22 and you're cleared for takeoff when you're ready.' this problem arose because: captain was using an unapproved headset -- thus -- communication in the cockpit was difficult, vague and unclr verbiage used by the ground controller. Human factors to be considered. Captain had displayed unsound judgement several times prior during this trip. This caused myself to become extra vigilant of the captain's decisions and physical actions. More accurately, I had become hypervigilant. I was paying extra attention to make sure the pre takeoff checks were all completed properly, particularly the items he was responsible for. This environment was ripe with potential distrs which this incident reveals.

Google
 

Original NASA ASRS Text

Title: COMMUTER LTT CROSSES HOLD LINE AND ALMOST ENTERS ACTIVE RWY.

Narrative: ON TAXI-OUT, I WAS RUNNING THE 'TAXI' AND 'BEFORE TKOF' CHKLISTS. SOME OF WHICH REQUIRED CHALLENGE AND RESPONSE, AND OTHERS JUST TO VERBALIZE WITH A RESPONSE. THE CAPT DID NOT HAVE A HEADSET AND WAS USING JUST ONE EARPIECE. OUR INSTRUCTIONS FROM THE GND CTLR WERE TO 'TAXI TO RWY 21 VIA BRAVO AND BRAVO 6 AND YOU WILL BACK TAXI ON RWY 21.' THIS WAS DUE TO ANOTHER ACFT THAT WAS BLOCKING ACCESS TO RWY 21 ON BRAVO AS HE WAS WAITING FOR A FLOW CTL CLRNC. I UNDERSTOOD THIS AS NOT A CLRNC TO TAXI ON TO THE ACTIVE RWY. AS I CONTINUED TO RUN THE CHKLISTS, I WAS DISTRACTED BY THE FACT THAT THE CAPT WAS NOT WEARING A HEADSET WITH A MIKE. I WAS WEARING ONE WITH THE L EAR UNCOVERED. THIS MADE COM EXTREMELY DIFFICULT AND WHEN I VERIFIED THE INSTRUCTIONS WITH HIM, HE NODDED YES. MY CONCERNS ABOUT THIS LACK OF A HEADSET AND DIFFICULT COM WERE VOCALIZED TO THE CAPT PRIOR TO HIS INCIDENT ON THE TRIP. WHILE COMPLETING THE CHKS, I LOOKED OUT AND NOTICED THE CAPT WAS XING THE HOLD SHORT LINE ON B6. I IMMEDIATELY TOLD HIM TO 'STOP, WE MUST CALL TWR FIRST!' HE STOPPED, AND STATED THAT NO WE DID NOT NEED TO CALL THEM. AT THE NEXT MOMENT, GND CALLED AND INSTRUCTED US TO DO JUST THAT. I CONTACTED THEM AND THEY THEN CLRED US TO 'BACK TAXI ON RWY 22 AND YOU'RE CLRED FOR TKOF WHEN YOU'RE READY.' THIS PROB AROSE BECAUSE: CAPT WAS USING AN UNAPPROVED HEADSET -- THUS -- COMMUNICATION IN THE COCKPIT WAS DIFFICULT, VAGUE AND UNCLR VERBIAGE USED BY THE GND CTLR. HUMAN FACTORS TO BE CONSIDERED. CAPT HAD DISPLAYED UNSOUND JUDGEMENT SEVERAL TIMES PRIOR DURING THIS TRIP. THIS CAUSED MYSELF TO BECOME EXTRA VIGILANT OF THE CAPT'S DECISIONS AND PHYSICAL ACTIONS. MORE ACCURATELY, I HAD BECOME HYPERVIGILANT. I WAS PAYING EXTRA ATTN TO MAKE SURE THE PRE TKOF CHKS WERE ALL COMPLETED PROPERLY, PARTICULARLY THE ITEMS HE WAS RESPONSIBLE FOR. THIS ENVIRONMENT WAS RIPE WITH POTENTIAL DISTRS WHICH THIS INCIDENT REVEALS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.