GPS
Yes some companies do have it fitted and used it for unreliable airspeed proceedures before the accident.
Flew the route with full enlarging crew - two captains. Copilots and engineers.
Always one captain in the flight deck and sometimes the resting captain would join us for the ITCZ transit.
Cheap option one captain - blame the companies and regulators.
As to the lack of airmanship from the captain!