Date: 202105
Local time of day: 1201-1800
Location: LAX.Airport, CA
Light: Daylight
Aircraft: B737-700
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B LAX
ATC / advisory: TRACON SCT
Second aircraft: B777 Undifferentiated or Other Model
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Communication Breakdown
Second reporter function: Pilot Not Flying; First Officer
Anomaly: ATC Issue All Types; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Illness / Injury; Inflight Event / Encounter Wake Vortex Encounter
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Became Reoriented
Contributing factors: Environment - Non Weather Related; Procedure; Human Factors
Primary problem: Human Factors

Narrative: We had been cleared the ILS 25L Approach while on the ANJLL Arrival and assigned 250 knots. At about 12;000 feet; we got a call from the cabin that the passenger we had called STAT-MD for earlier in the flight; was feeling worse. I asked the First Officer to call OPS for medical assistance to meet us at the gate. When he returned back to the ATC frequency; we were approaching 10;000 feet and hit wake turbulence sufficiently strong to cause the airplane to go into control wheel pitch and roll. I redirected the aircraft to KRAIN; re-engaged LNAV and VNAV; and asked ATC what we were following.  I was told we were following nothing. This didn't make sense since we had just hit very strong wake turbulence. While established on final; ATC told us to slow to 170 knots. This surprised both of us; because the last speed assignment we recalled being given was 250 knots. 170 knots would be a huge speed reduction and we were still about 25 miles out. ATC then asked us if we were at 210 knots. We told the Controller no; and that we had been assigned 250 knots. He told us we had been instructed to slow to 210 knots back when we complained about the wake turbulence (approaching 10;000 feet). We were now overtaking a B777 ahead; so our approach clearance was canceled. We were given vectors for spacing and vectored back onto the localizer and then re-cleared the ILS 25L. Neither the First Officer no I recall hearing the 210 knot speed assignment. We had only heard 250 knots and read that back. The 210-knot speed assignment probably occurred about the time the Flight Attendant called us about the passenger feeling ill again and just as we hit the wake turbulence.


Second narrative: A bunch of things happened at once which led to us missing a slower speed assignment. On the arrival to LAX; cleared the approach to 25L and told to maintain 250 knots. The flight attendant called up and said that our previous medical issue in the back (we had earlier talked to STAT-MD and gotten clearance to continue) was not feeling well again; and asked for paramedics. As the Pilot Monitoring; I called OPS at LAX; to arrange for emergency personnel - meaning I was off frequency. At the same time; we encountered wake turbulence; strong enough to knock the aircraft out of both LNAV/VNAV. The Captain; Pilot Flying; reported the wake turbulence to Approach; after getting the aircraft established on profile; apparently ATC told us to slow to 210 knots. Neither of us heard or read back the speed change. A few miles later Approach canceled our approach clearance and said we were too fast. We responded that we were assigned 250. They said no; we were given 210.


Synopsis: B737-700 flight crew reported missing an ATC speed assignment on arrival into LAX when they were distracted by a wake turbulence encounter in trail of a heavy B777.