Date: 201906
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Light: Dusk
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Flight Deck / Cabin / Aircraft Event Illness / Injury; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Attendant; Person Flight Crew
When detected: Taxi
Result: Flight Crew Returned To Gate; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Environment - Non Weather Related; Aircraft
Primary problem: Aircraft

Narrative: I was Captain on Flight XXXX from ZZZ to ZZZ1. The First Officer and I we were on our last leg of a three-day trip. We blocked out of Gate X (XX:49) and subsequently blocked back into the same gate at XY:09. Due to a short taxi to Runway XXR; I called for both engines to be started upon pushback. After starting the #2 engine the FO called; 'isolate/ventilate' and immediately following his After Start Flow; he asked 'Do you smell that?' I responded with 'What does it smell like?' He stated; 'wet socks.' I immediately instructed him to open his window and stick his head out and [I] did the same. The push crew was disconnected; but I verbally instructed them to standby as we had a situation unfolding. After getting some outside air ventilation through the cockpit I came back in to call the FAs on the interphone to inquire about the situation in the cabin. They stated that the smell/fume was rather intense back there and thus I told them that we're making a gate return. I made as calm and generic of a PA as I could think of to inform the passengers that we were returning to the gate. Upon arrival back at the gate I instructed the FAs to open all doors as soon as feasible in order to ventilate the cabin as much as possible. We did lose an estimated 4-5 minutes waiting for the ramp crew to be in position and the Ops Agent to pull up the jetway. In total we were off the gate for 22 minutes. During the return to gate event we asked for medics to meet us at the gate through our operations frequency. Once back at Gate XX I talked with the Ops Agent and Maintenance about our next course of action. This is also when I first started to see the FA's exhibit symptoms and they did in fact state to me that they were feeling ill. The decision was made to deplane; and I made another fairly generic PA stating that we would be deplaning the aircraft shortly; so that it may be inspected and for the passengers to please remain in the gate area upstairs. As I became rather busy coordinating things; I presume that the Ops Agent completed the deplaning process. During the initial period of the gate return there was a flurry of activity on the aircraft and jetway with me trying to coordinate with the Ops Agent; FAs; Maintenance; ZZZ Airport Representative and the medics. When I had time; I eventually called Dispatch and brought them into the loop. I believe the FO also called Crew Scheduling to advise them of the situation and made a logbook entry of the fumes event. I tried to prioritize communications and duties during this time. After deplaning; the FA's symptoms seemed to be increasing in intensity even though all six of the flight crew were now out on the jetway. By this time the First Officer and I were also feeling symptoms. Eventually the six of us found ourselves sitting in wheelchairs on the jetway being evaluated by medics who subsequently called for ambulances to take us to the hospital. The medics took all of our blood pressures and found all of them to be elevated. We were then moved by the wheelchairs from the jetway into the terminal immediately next to the Ops Agent podium. After a few minutes we were moved to the break room. To elaborate on our collective symptoms; they can best be described as shortness of breath; dizziness; headache; elevated blood pressure; sweating; clammy/flush face; confusion; nausea; feeling 'hypoxic'; vomiting; and a feeling of being 'drunk' insofar as having a noticeably difficult time putting thoughts and words together. To be clear; these symptoms were experienced to varying degrees by the six crew members. Individual medical records would need to be consulted as far as who experienced what and to what intensity. Of note is that the ZZZ Airport Representative that met the flight upon our return to Gate XX also got sick and experienced symptoms to the point of having to get evaluated by the medics on the jetway. My personal symptoms included abnormally excessive sweating; dizziness; a clammy/flush face; significantly elevated blood pressure; headache; the 'drunk' feeling; and eventually confusion and an inability to focus. In particular I remember being on several phone calls (Chief Pilot; [union]; etc.); and having a noticeably difficult time concentrating and formulating thoughts and speech. While the medics arrived at our jetway fairly quickly; given the symptoms that we were exhibiting it did take a rather long time to be loaded into the ambulance(s) and admitted to the ER. Eventually all six of us found ourselves in the same room for medical treatment and evaluation including blood draws. Several hours later the entire crew was discharged.


Second narrative: [Report narrative contained no additional information.]


Synopsis: B737-800 flight crew reported strong 'dirty socks' smell during pushback while completing the engine start. Gate return was executed; and the crew received medical treatment after feeling ill.