SINGAPORE (Reuters) – Boeing Co said an alert for angle-of-attack (AOA) sensors on its 737 MAX jets was “not activated as intended” for some customers, responding to reports it failed to tell Southwest Airlines Co and the U.S regulator that the optional feature was deactivated before a crash in Indonesia in October.

FILE PHOTO: An aerial photo shows Boeing 737 MAX airplanes parked on the tarmac at the Boeing Factory in Renton, Washington, U.S. March 21, 2019. REUTERS/Lindsey Wasson/File Photo

Erroneous AOA sensor readings that led to aggressive nose-down inputs by a computer have been linked to deadly 737 MAX crashes in Indonesia and Ethiopia, according to preliminary reports from investigators.

Boeing offered customers two optional paid features relating to AOA. The first was an