Narrative:

After we proceeded to spot 2 on the ground of bwi airport, ground called us to hold on the spot, give way to 737, taxi runway 15L, a, J, (I think). I was confused when he said runway 15L since ATIS information was -X 5 overcast 1 - RF 60/60 calm 29.81 29.81 33L/right I should have not accepted the clearance since I did not fully understand the clearance. The captain, so I thought, understood it. I was going to verify the clearance but the frequency became congested. We actually taxied a, B, south, J into ILS critical area. Ground told a dash 8 he would follow us. There were 2 dash 8's. 1 dash 8 was holding short of B on south, the other holding short of south on J. We felt the only way a dash would follow us is if we turned right on B then left on X. While I was making PA when tower told captain we taxied the wrong way, and we were in ILS critical area! He said, however, it was not going to be a problem. I should have written the taxi clearance down, also should not have started to taxi unless we were positive on the route to take. I'm not sure what would prevent this as it was the 4TH day of a 4-DAY trip. I have noticed a much higher a rate of mistakes made on the 4TH day of 4-DAY trips. This 4-DAY trip has duty times of almost 9.5 hours, 13 hours, 10.8 hours and 9 hours on last day. The only other thing would have been to stop and wait until we could verify the clearance.

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Original NASA ASRS Text

Title: COMMUTER LTT TURNS WRONG DIRECTION ON TAXI OUT.

Narrative: AFTER WE PROCEEDED TO SPOT 2 ON THE GND OF BWI ARPT, GND CALLED US TO HOLD ON THE SPOT, GIVE WAY TO 737, TAXI RWY 15L, A, J, (I THINK). I WAS CONFUSED WHEN HE SAID RWY 15L SINCE ATIS INFO WAS -X 5 OVCST 1 - RF 60/60 CALM 29.81 29.81 33L/R I SHOULD HAVE NOT ACCEPTED THE CLRNC SINCE I DID NOT FULLY UNDERSTAND THE CLRNC. THE CAPT, SO I THOUGHT, UNDERSTOOD IT. I WAS GOING TO VERIFY THE CLRNC BUT THE FREQ BECAME CONGESTED. WE ACTUALLY TAXIED A, B, S, J INTO ILS CRITICAL AREA. GND TOLD A DASH 8 HE WOULD FOLLOW US. THERE WERE 2 DASH 8'S. 1 DASH 8 WAS HOLDING SHORT OF B ON S, THE OTHER HOLDING SHORT OF S ON J. WE FELT THE ONLY WAY A DASH WOULD FOLLOW US IS IF WE TURNED R ON B THEN L ON X. WHILE I WAS MAKING PA WHEN TWR TOLD CAPT WE TAXIED THE WRONG WAY, AND WE WERE IN ILS CRITICAL AREA! HE SAID, HOWEVER, IT WAS NOT GOING TO BE A PROB. I SHOULD HAVE WRITTEN THE TAXI CLRNC DOWN, ALSO SHOULD NOT HAVE STARTED TO TAXI UNLESS WE WERE POSITIVE ON THE RTE TO TAKE. I'M NOT SURE WHAT WOULD PREVENT THIS AS IT WAS THE 4TH DAY OF A 4-DAY TRIP. I HAVE NOTICED A MUCH HIGHER A RATE OF MISTAKES MADE ON THE 4TH DAY OF 4-DAY TRIPS. THIS 4-DAY TRIP HAS DUTY TIMES OF ALMOST 9.5 HRS, 13 HRS, 10.8 HRS AND 9 HRS ON LAST DAY. THE ONLY OTHER THING WOULD HAVE BEEN TO STOP AND WAIT UNTIL WE COULD VERIFY THE CLRNC.

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.