Date: 201310
Location: C90.TRACON, IL
Flight conditions: IMC
Weather elements / visibility: Rain
Light: Night
Aircraft: B777 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class B ORD
ATC / advisory: TRACON C90
Aircraft component: FMS/FMC
Component problem: Design; Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Workload; Troubleshooting; Human-Machine Interface; Distraction; Confusion; Communication Breakdown
Second reporter function: First Officer; Pilot Flying
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Overcame Equipment Problem; Flight Crew Took Evasive Action
Contributing factors: Aircraft; Procedure; Weather
Primary problem: Ambiguous

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.


Second narrative: On descent into Chicago; O'Hare on the BENKY 2 RNAV Arrival; we had a minor flight path deviation and delay in slowing to 250 knots below ten thousand feet.Due to anticipating an involved RNAV arrival with multiple speed and step-down restrictions; landing on new Runway 28C; and newly imposed taxi-flow procedures we began reviewing and briefing for the approach as early as Denver. Our brief; as per SOP; was in anticipation of landing on 28C; however we did discuss the possibility of a runway change to 27R or 27L. I; as the Pilot Flying; also briefed that I would be using the autopilot on the STAR to reduce workload during the arrival. Anticipated weather conditions were night; light rain; quartering crosswind of approximately 15-20 knots on landing.Prior to BDF we were assigned 300 knots and two modified altitude restrictions prior to BENKY. We crossed BENKY at 12;000 feet and 300 knots as requested. Inside NEWRK; ORD Approach issued a new altimeter setting. When the Captain attempted to get the ATIS via ACARS it locked up and the SEND command became frozen. It required him to get the ATIS via VHF. I believe it was near ASHTN that we were assigned Runway 27L. Several things occurred at this point. When attempting to re-program the FMC to 27L the aircraft made a hard right turn over PETAH as if returning to BENKY. As the Pilot Flying; it required disconnecting the autopilot to make an aggressive turn back toward PETAH. The Captain informed ATC we were turning back toward PETAH which ATC acknowledged. In addition; during this time period and for no apparent reason; the FMC went into STANDBY mode. I was descending to nine thousand feet and it was the last thousand feet to nine thousand that I realized I was late slowing to 250 knots.The Captain and I both erroneously believed we were to head north toward KURKK for the 27 runways. It was at this point while the FMC was in standby mode that ATC issued direct MONKZ. Shortly after being given a vector and I believe after a frequency change; ATC told us we had missed a couple of their radio calls. Once on vectors and the FMC out of STANDBY mode; we extended 27L and landed uneventfully.I believe the contributing factors were:-Multiple ATC altitude and speed adjustments to the BENKY2 RNAV arrival. -VNAV having difficulty keeping up with 300 knot descents on a RNAV arrival.-ACARS and FMC malfunction including difficulty programming.-Late runway assignment requiring FMC program changes over a waypoint (PETAH) that forks into two different directions for different runways.-Standard taxi flow instructions not readily available on 10-7 or 10-9 pages.-Unfamiliarity with new O'Hare runway flow procedures.


Synopsis: 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.