B767 Captain reported a track deviation occurred departing IAD when a wake turbulence encounter interrupted the flight crew's workflow.
Synopsis
B767 Captain reported a track deviation occurred departing IAD when a wake turbulence encounter interrupted the flight crew's workflow.
Narrative
Hand-flying the JCOBY4 RNAV departure out of IAD. Leveling off at 10;000 [ft.] and accelerating to 280 knots. Departure clears direct GRIIM; I begin the turn towards GRIIM by hand. FO selects GRIIM in FMC and executes; just as we hit moderate wake turbulence. I was task-saturated with the acceleration; turn and reacting to the wake turbulence; and do not know if FO ever engaged LNAV. I stopped [the] turn at what I believed pointed at GRIIM; but must have been about 30 degrees short. Shortly after; departure issued a 'Turn immediately to 150 deg. I made the turn; and during the turn got a TCAS TA. We determined that the traffic was no longer a threat; and I engaged the autopilot. Departure asked if we could go directly to GRIIM; and we replied 'Yes.' I then watched FO bring GRIIM to the top of the FMC; execute; and I engaged LNAV. The plane began to turn the wrong way; so I went to Heading Select and turned back towards GRIIM. I asked the FO to hand-type GRIIM back into the FMC and; since we were very near the way point; sequence the next way point. He was trying to re-enter the whole departure; I looked at the Jepp and determined that SOOKI was there; after a discontinuity. I removed the discontinuity; executed; engaged LNAV; and the plane made the proper turn. No further difficulties encountered for the rest of the flight."
Second reporter narrative
While departing IAD on the JCOBY4 Departure we inadvertently left the desired track. We were initially being radar vectored after departing 30 on a heading 360 proceeded by a clearance to RIGNZ in a climb to FL100; I selected the fix and the CA confirmed. I executed the command and reached over to engage LNAV. The CA made a comment that he will want the fix double clutched. I do not recall if I verified the LNAV FMA. Upon turning and rolling out to RIGNZ the CA commented that it looked OK. I therefore did not re enter the fix in the FMC. We continued the climb and leveled at FL100. We discussed accelerating to 280kts; which was accomplished. The CA was hand flying and I believed we were in LNAV at FL100 on the departure; I proceeded to accomplish FMC tasks; determining time for the oceanic clearance; etc. while completing these tasks we received an urgent heading to 150 which I responded and the CA accomplished followed by a TA caution. We subsequently were given a clearance to GRIIM which was selected verified executed but dropped out. Requiring me to reference the SID and hand type the fix. We were also given a clearance to climb to FL 190. We now had a discontinuity which required verification of fixes against the SID chart. We subsequently got the departure correctly sequenced and the AP on and in LNAV and initiated the climb without further complication.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.