Nigeria, March 13 -- The United States Federal Aviation Administration (FAA) has insisted there was "no basis" to suspend commercial flights on Boeing 737 MAX 8, the model that crashed in Addis Ababa, Ethiopia, on Sunday.

The U.S. aviation authorities' defiance lingers despite several countries grounding the plane amidst fresh revelations that several American pilots had for months lodged complaints that the MAX 8's manual was insufficient for their understanding, according to the Dallas Morning News in Texas.

The pilots' complaints, which included a lack of adequate information on how to handle MAX 8's autopilot during a sudden nosedive, were logged in a public database for in-flight concerns. The pilots' concerns were similar to the s...