UPDATE 3-Boeing inadvertently made 737 MAX alert optional, denies safety risk

CHICAGO/WASHINGTON, May 5 (Reuters) - Boeing Co said on Sunday it had inadvertently made an alarm alerting pilots to a mismatch of flight data optional on the 737 MAX, instead of standard as on earlier 737s, but reiterated that the missing display represented no safety risk.The U.S. planemaker has been trying for weeks to dispel suggestions that it made airlines pay for safety features after it emerged that an alert designed to show discrepancies in Angle of Attack readings from two sensors was