Regional Jet 900 (CRJ900)
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Communication Breakdown
ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Wake Vortex Encounter
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action; Flight Crew Returned To Clearance
Procedure; Environment - Non Weather Related; Human Factors
While being routed in sequence for the EAGUL6 arrival into PHX our aircraft was experiencing severe wake turbulence with banks between 30 and 45 degrees. After two occurrences; we requested ATC for an offset to avoid the wake of the leading aircraft. ATC instructed us to offset to the north and continue the arrival. The Captain and I verified the instruction to offset to the north and continue the arrival. As pilot flying; I put the autopilot in heading mode and set the heading 15 degrees to the right while the Captain programmed the FMS for the north offset by 5 miles. We verified the programming with each other and I placed the autopilot in NAV mode to resume the arrival. Two or three minutes later; ATC said that he instructed us to offset by only one mile and gave us a new clearance to join the BRUSR1 arrival. The Captain and I reviewed the sequence of events; and neither of us recalled hearing or reading back the instructions to include an offset of one mile. No other issues arose and ATC gave no other feedback regarding the instructions or our actions.In hindsight; we may have verified the instructions given to us by ATC although we were unaware of the possible error in the delivery or read back of the instructions.
CRJ-900 First Officer reported a track deviation occurred following a wake turbulence encounter approaching PHX.