Narrative:

While descending into ord at night; in rain we encountered multiple anomalies which lead to a minor flight path deviation. In anticipation of challenges associated with the new traffic flow at ord; we thoroughly briefed possibilities and contingencies for an arrival as early as denver. We programmed an arrival to runway 28C (new runway) as the pilot bulletins and notams indicated this was the new arrival runway. This was further reinforced by the chicago dispatcher's notes on the sabre flight plan that indicated 28C was the expected landing runway. We discussed the BENCKY2 arrival and reviewed all of the step downs and speed restrictions. We did consider that we might be assigned a different runway; as 28C; 27L and 27R were all in use. But; as per SOP's; we briefed only one runway until assignment; 28C; with the caveat that we would brief the new runway if changed. While descending at 300 KTS assigned; ATC modified all of the fix altitudes and speeds on the BENCKY2. We programmed these initially without problem. When ATC offered a new altimeter; I announced I would be getting a new ATIS. While using the misc as (comm) function to obtain ATIS; the system locked up. I tried twice; trying to get a send prompt. My FMS then went into standby mode; which I announced to the flying first officer. She would have to enter her own crossing restrictions; while I obtained new ATIS via radio. We were assigned runway 27L at a point I believe was approaching ashtin. While programming the new runway on autopilot; the plane began to make a hard right turn; as if it were returning to BENCKY2. First officer disengaged ap and manually corrected back to track. During this we were in weather; at night; flying the requested higher speeds and descending to 9000 feet. We inadvertently maintained the higher speed to 9000; correcting prior to level off. Here is where I introduced further error into the operation. I made an incorrect inference that the north prong of the BENCKY2 arrival served both north (27R; 27L) runways. The FMC would not (and properly so) offer the north fork routing to runway 27L. While struggling with this misinterpretation; approach control (thankfully) issued a vector. At some earlier point; I should have asked for a vector and speed; but in an effort to be helpful to O'hare's new runway flow; I tried to keep on task with programming. To further our contrition; ATC admonished us for not responding to their calls; which was deserved as we were trying to figure out what the FMC was trying to do. I believe the following are the contributing factors. The BENCKY2 arrival has myriad fixes and speed and altitude constraints; including at and above and below at bylaw. Both the first officer and I generally fly the pacific and though we welcomed the change to domestic; it presents its own new challenges. The FMC dropping into standby mode during this busy arrival began the sequence of events; which I did not handle well. The high speed assignments; altitude variations; weather; and errant FMC were all contributing. I must state that this failure was not for a lack of effort; or any disrespect for ATC; as we planned early. It was a chain of circumstances that ultimately led to the deviations. I accept full responsibility for these deviations; and in review the only thing I would do differently is: get a better understanding of the last section of the BENCKY2 and ask ATC for a vector despite their busy controlling. I thought approach; with the exception of a late runway assignment (which may be beyond their control); though terse; handled their end very well.

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Original NASA ASRS Text

Title: A B777 crew describe their difficulty reprogramming the BENCKY 2 RNAV after a runway change from the planned 28C to 27L when the FMC and ACARS both temporarily malfunctioned which required ATC vectors.

Narrative: While descending into ORD at night; in rain we encountered multiple anomalies which lead to a minor flight path deviation. In anticipation of challenges associated with the new traffic flow at ORD; we thoroughly briefed possibilities and contingencies for an arrival as early as Denver. We programmed an arrival to Runway 28C (new runway) as the Pilot Bulletins and NOTAMs indicated this was the new arrival runway. This was further reinforced by the Chicago Dispatcher's notes on the SABRE Flight Plan that indicated 28C was the expected landing runway. We discussed the BENCKY2 arrival and reviewed all of the step downs and speed restrictions. We did consider that we might be assigned a different runway; as 28C; 27L and 27R were all in use. But; as per SOP's; we briefed only one runway until assignment; 28C; with the caveat that we would brief the new runway if changed. While descending at 300 KTS assigned; ATC modified all of the fix altitudes and speeds on the BENCKY2. We programmed these initially without problem. When ATC offered a new altimeter; I announced I would be getting a new ATIS. While using the Misc AS (COMM) function to obtain ATIS; the system locked up. I tried twice; trying to get a SEND prompt. My FMS then went into standby mode; which I announced to the flying First Officer. She would have to enter her own crossing restrictions; while I obtained new ATIS via radio. We were assigned Runway 27L at a point I believe was approaching ASHTIN. While programming the new runway on Autopilot; the plane began to make a hard right turn; as if it were returning to BENCKY2. First Officer disengaged AP and manually corrected back to track. During this we were in weather; at night; flying the requested higher speeds and descending to 9000 feet. We inadvertently maintained the higher speed to 9000; correcting prior to level off. Here is where I introduced further error into the operation. I made an incorrect inference that the north prong of the BENCKY2 arrival served both north (27R; 27L) runways. The FMC would not (and properly so) offer the north fork routing to Runway 27L. While struggling with this misinterpretation; Approach Control (thankfully) issued a vector. At some earlier point; I should have asked for a vector and speed; but in an effort to be helpful to O'Hare's new runway flow; I tried to keep on task with programming. To further our contrition; ATC admonished us for not responding to their calls; which was deserved as we were trying to figure out what the FMC was trying to do. I believe the following are the contributing factors. The BENCKY2 Arrival has myriad fixes and speed and altitude constraints; including at and above and below at BYLAW. Both the First Officer and I generally fly the Pacific and though we welcomed the change to domestic; it presents its own new challenges. The FMC dropping into standby mode during this busy arrival began the sequence of events; which I did not handle well. The high speed assignments; altitude variations; weather; and errant FMC were all contributing. I must state that this failure was not for a lack of effort; or any disrespect for ATC; as we planned early. It was a chain of circumstances that ultimately led to the deviations. I accept full responsibility for these deviations; and in review the only thing I would do differently is: Get a better understanding of the last section of the BENCKY2 and ask ATC for a vector despite their busy controlling. I thought Approach; with the exception of a late runway assignment (which may be beyond their control); though terse; handled their end very well.

Data retrieved from NASA's ASRS site as of July 2013 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.