A B757-200 crew incurred on bos runway 4L while starting an engine during taxi.

Attributes
ACN	643465
Time
Date	200501
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bos.airport
State Reference	MA
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	ground : taxi
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : cfi pilot : atp
Experience	flight time last 90 days : 100 flight time total : 13000 flight time type : 3000
ASRS Report	643465
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	incursion : runway non adherence : clearance non adherence : far
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance controller : issued advisory
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Company Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

After pushback; we started just the left engine. We commonly taxi on 1 engine to save fuel. Ground gave clearance to taxi to runway 9; hold short of runway 4L. I read back 'hold short runway 4L.' while I was starting the #2 engine; ground called and asked; 'are you crossing runway 4L?' the captain was taxiing aircraft. I looked up and we were 1/2 way across runway 4L. I stated; 'er; yes -- sorry.' controller said; 'ok; just snag it up behind the aircraft in front of you' to clear the runway. No conflict with landing traffic. The captain stated he knew as soon as he started across he screwed up. I was unaware we were crossing as my head was down starting the second engine. I prefer to start both engines at gate so I can be 'outside' along with the captain. Also contributing would be screwy intersection at runway 4L and runway 9 at bos.

Original NASA ASRS Text

Title: A B757-200 CREW INCURRED ON BOS RWY 4L WHILE STARTING AN ENG DURING TAXI.

Narrative: AFTER PUSHBACK; WE STARTED JUST THE L ENG. WE COMMONLY TAXI ON 1 ENG TO SAVE FUEL. GND GAVE CLRNC TO TAXI TO RWY 9; HOLD SHORT OF RWY 4L. I READ BACK 'HOLD SHORT RWY 4L.' WHILE I WAS STARTING THE #2 ENG; GND CALLED AND ASKED; 'ARE YOU XING RWY 4L?' THE CAPT WAS TAXIING ACFT. I LOOKED UP AND WE WERE 1/2 WAY ACROSS RWY 4L. I STATED; 'ER; YES -- SORRY.' CTLR SAID; 'OK; JUST SNAG IT UP BEHIND THE ACFT IN FRONT OF YOU' TO CLR THE RWY. NO CONFLICT WITH LNDG TFC. THE CAPT STATED HE KNEW AS SOON AS HE STARTED ACROSS HE SCREWED UP. I WAS UNAWARE WE WERE XING AS MY HEAD WAS DOWN STARTING THE SECOND ENG. I PREFER TO START BOTH ENGS AT GATE SO I CAN BE 'OUTSIDE' ALONG WITH THE CAPT. ALSO CONTRIBUTING WOULD BE SCREWY INTXN AT RWY 4L AND RWY 9 AT BOS.

Data retrieved from NASA's ASRS site as of January 2009 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.