On page 41 of the preliminary report (pdf), third paragraph, begins with "se detectó...", says "
there was detected a non-authorized en-route habilitation session. One "crew member" acted as co-pilot, with Commander's surveillance until he (the Commander) asked for the control. The aeronautical authorities were given word of this".
This means a THIRD CREW member was in the cockpit at the moment of the TO procedure, acting as co-pilot and made the TO procedure actions until the PIC asked for the controls of the AC.
This was confirmed in a press conference in Mexico and is published in several media:
https://elpais.com/internacional/201...32_422381.html
http://www.eluniversal.com.mx/carter...-de-aeromexico