2010-10 · NASA ASRS report 915229
An Embraer flight crew deviated from the assigned DFW SID following a wake vortex encounter; but improper autoflight programming also played a part.
I was Captain and the pilot flying; [and we were] assigned a Clare 2 departure from Runway 17R. We completed all required checks and checklists prior to departure. Departure; runway; first fix; Q value; confirm GPS not in HDG mode. The takeoff roll was normal; V1; Rotation; Positive Rate; Gear up. Then about 200 to 300 FT there was a wake turbulence encounter from the previous departure; a Boeing 737. The aircraft buffeted; rolled left and pitched up. I placed my right hand on the thrust levers prepared to command Max Thrust if required; pulled the aircraft nose upward to exit the wake turbulence. We exited the wake turbulence successfully. I scanned the aircraft instruments to ensure that the aircraft was stable and on track. The EHSI was in Terminal Scaling; the CDI showed a slight left course deviation; (the aircraft was to the right of the course; the course was to the left of the aircraft) approximately 2 CDI needle widths to the left of the CDI centered position. The CDI was still over the aircraft symbols left wing; the left wing tip was displayed to the left of the CDI needle. About this time; the First Officer observed; and stated that the aircraft was still in Roll mode; the First Officer selected NAV and the Command Bars '[we] bobbled' left; then right; then showed a slight left turn. Then we received a radio call from ATC asking 'Are you on the RNAV Departure?' After confirming the aircraft's track on the left and right CDIs and MFDs the First Officer responded 'Affirmative'. ATC then inquired 'Do you see the MD-80 at 1:00?' Again the First Officer responded 'Affirmative.'NOTE: The MD-80 appeared to be in the normal position for a departure off Runway 18L; it did not appear to be any closer than normal. ATC said nothing more about the event;or loss of separation; there was no heading issued; no collision avoidance instructions were issued. Two (2) Center frequencies later a Controller said 'Possible Pilot Deviation; call [phone number].' (You may consider asking ATC to delay this radio call until the flight is on the ground because upon its receipt; both pilots were engaged in trying to understand the event and aircraft control and monitoring may have suffered.) Upon landing I called the number and spoke with an individual; [and] I was advised that he would be filing an alleged pilot deviation. The wake turbulence event occurred below the floating altitude waypoint 1;080 FT. It is very possible that the aircraft was blown/drifted to the right (west) prior to reaching the floating altitude waypoint. Preliminary information: seeing that the No Transgression Zone is approximately 2;300 FT wide and begins approximately 800 FT to the right of the Runway 17R centerline there is no margin for error in the DFW RNAV departures. Looking at the CDI Scaling in Terminal mode; 2 Dots = 1 mile; 1 Dot = 1/2 mile; 1/2 Dot = 1/4 mile; 1/4 Dot = 800 FT. The deviation displayed on the Captains CDI indicated a deviation of less than 800 FT. From this position; having not reached the floating waypoint; the aircraft may have already deviated from the RNAV Departure; continued to climb to the Floating Altitude Waypoint 1;080 FT where the FMS would then command a turn towards the first waypoint; TREXX.
This event occurred because the NAV mode was not selected after takeoff to comply with the RNAV departure procedure. The airplane was on a 174 degree heading; which is runway heading; and stayed on that heading because it remained in the ROL mode. This was the case until I realized that we were slightly off course and immediately selected the NAV mode. There was a slight wind from the east; or the left side of the airplane; that apparantly blew us slightly to the right of course. The NAV mode was selected late because the Captain never called for selection of the NAV mode and I didn't query him about this due to the distraction from the wake turbulence. In addition; I was tasked with monitoring the altitude to call out acceleration altitude and then running the After Takeoff Flows and Checklist. As a result; I was performing other tasks and had my head down reading the checklist before noticing the deviation from course and the incorrect lateral mode selection. This was also my first flight with this Captain. I have never flown with this Captain before and later discovered that his recent flying experience was minimal as he stated this was only his third trip in the past few months due to an illness. He was not very standard or consistent with callouts; standard operating procedures; or checklist usage. I queried him about several revisions that we had recently implemented. He claimed that he had the revisions but had not really looked them over yet. This became a recurring issue between us for the rest of the trip. He appeared to be distracted for the rest of the trip; causing an increase in my awareness of our working environment. Lastly; I later discovered that during the takeoff; there was an apparant loss of separation between our aircraft and the MD80 departing from the west side of the airport. The DFW Tower nor the controller working Regional Departure ever stated this to us on frequency and never issued a traffic alert; never attempted to vector us; or never attempted to level us off at a lower altitude to correct the separation problem. We never knew there was a sparation problem or a possible deviation until we were told by Fort Worth Center to give Regional Departure a call on the ground after landing. At this point; my mind was not thinking about the rest of the flight ahead and I became even more distracted as a result.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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