Flight crew misunderstood taxi clearance and continued taxiing onto an active runway.

Attributes
ACN	315470
Time
Date	199509
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : bos
State Reference	MA
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : bwi
Operator	common carrier : air carrier
Make Model Name	MD-88
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	ground other : taxi
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Beechcraft Twin Turboprop Jet Undifferentiated or Other Model
Operating Under FAR Part	Part 135
Flight Phase	landing other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : flight engineer pilot : instrument
Experience	flight time last 90 days : 180 flight time total : 8200 flight time type : 180
ASRS Report	315470
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 9000 flight time type : 1800
ASRS Report	315471
Events
Anomaly	conflict : ground critical incursion : runway non adherence : clearance non adherence : published procedure other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	Other
Miss Distance	vertical : 150
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Intra Facility Coordination Failure Operational Error

Narrative:

Holding short (#1) of runway 22R, bos tower instructed us to cross runway 22R and taxi to runway 22L, then immediately canceled those instructions and told us to taxi into position and hold on runway 22R. As we were pulling onto the runway, tower then instructed us to cross runway 22R, and taxi into position and hold on runway 22L. 'You will be going right out.' we crossed runway 22R and while taxiing to runway 22L, checked the weight and balance data for the new runway. Just before reaching runway 22L, tower gave us a frequency change and I checked in with the new frequency tower controller stating we were pulling into position and hold for runway 22L. Tower then said hold short runway 22L. By this time we were already on the extended overrun (displaced threshold) of runway 22L and I saw a beech commuter go over us and land in the normal touchdown zone of runway 22L. I acknowledged the hold short clearance and immediately tower came back with clearance onto the runway and hold. This whole sequence of events took place in about 1 min. There were no subsequent radio transmissions to indicate that anyone had noticed a conflict. I think the main cause was a late frequency change to the new (22L) runway tower frequency. Had it been given with the runway change instructions, there might have been time to clarify conflicting instructions. Supplemental information from acn 315471: the cockpit environment was busy checking the takeoff data for a new runway and making updates to the FMC to reflect the new runway. I am not sure anyone noticed how close and insidious this scenario was because of the rapid change in runway instructions and the fact the runways' controllers were on separate frequencys. This hindered our ability to have better situational awareness of arriving aircraft. I did not make a visual check to see if an aircraft was on short final as I was thinking about getting my aircraft ready to takeoff in a short period of time.

Original NASA ASRS Text

Title: FLC MISUNDERSTOOD TAXI CLRNC AND CONTINUED TAXIING ONTO AN ACTIVE RWY.

Narrative: HOLDING SHORT (#1) OF RWY 22R, BOS TWR INSTRUCTED US TO CROSS RWY 22R AND TAXI TO RWY 22L, THEN IMMEDIATELY CANCELED THOSE INSTRUCTIONS AND TOLD US TO TAXI INTO POS AND HOLD ON RWY 22R. AS WE WERE PULLING ONTO THE RWY, TWR THEN INSTRUCTED US TO CROSS RWY 22R, AND TAXI INTO POS AND HOLD ON RWY 22L. 'YOU WILL BE GOING RIGHT OUT.' WE CROSSED RWY 22R AND WHILE TAXIING TO RWY 22L, CHKED THE WT AND BAL DATA FOR THE NEW RWY. JUST BEFORE REACHING RWY 22L, TWR GAVE US A FREQ CHANGE AND I CHKED IN WITH THE NEW FREQ TWR CTLR STATING WE WERE PULLING INTO POS AND HOLD FOR RWY 22L. TWR THEN SAID HOLD SHORT RWY 22L. BY THIS TIME WE WERE ALREADY ON THE EXTENDED OVERRUN (DISPLACED THRESHOLD) OF RWY 22L AND I SAW A BEECH COMMUTER GO OVER US AND LAND IN THE NORMAL TOUCHDOWN ZONE OF RWY 22L. I ACKNOWLEDGED THE HOLD SHORT CLRNC AND IMMEDIATELY TWR CAME BACK WITH CLRNC ONTO THE RWY AND HOLD. THIS WHOLE SEQUENCE OF EVENTS TOOK PLACE IN ABOUT 1 MIN. THERE WERE NO SUBSEQUENT RADIO TRANSMISSIONS TO INDICATE THAT ANYONE HAD NOTICED A CONFLICT. I THINK THE MAIN CAUSE WAS A LATE FREQ CHANGE TO THE NEW (22L) RWY TWR FREQ. HAD IT BEEN GIVEN WITH THE RWY CHANGE INSTRUCTIONS, THERE MIGHT HAVE BEEN TIME TO CLARIFY CONFLICTING INSTRUCTIONS. SUPPLEMENTAL INFO FROM ACN 315471: THE COCKPIT ENVIRONMENT WAS BUSY CHKING THE TKOF DATA FOR A NEW RWY AND MAKING UPDATES TO THE FMC TO REFLECT THE NEW RWY. I AM NOT SURE ANYONE NOTICED HOW CLOSE AND INSIDIOUS THIS SCENARIO WAS BECAUSE OF THE RAPID CHANGE IN RWY INSTRUCTIONS AND THE FACT THE RWYS' CTLRS WERE ON SEPARATE FREQS. THIS HINDERED OUR ABILITY TO HAVE BETTER SITUATIONAL AWARENESS OF ARRIVING ACFT. I DID NOT MAKE A VISUAL CHK TO SEE IF AN ACFT WAS ON SHORT FINAL AS I WAS THINKING ABOUT GETTING MY ACFT READY TO TKOF IN A SHORT PERIOD OF TIME.

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.