National Transportation Safety Board investigators reviewing a July Asiana Airlines crash landing at San Francisco International Airport raised concerns about the safety certification of Boeing 777's controls design.
The investigators warn that the plane's automatic protection against stalling does not always automatically engage.
Experts at a hearing Wednesday and an investigative report say when the plane's autothrottle is placed in a "hold" mode, as it was during the Asiana flight, it is supposed to re-engage or "wake up" when it reaches minimum airspeed.
But a primary project pilot who oversaw the Boeing 787 flight tests for the Federal Aviation Administration told the NTSB that both the 787 and the 777 had the same anti-stall protection systems — and that the wake-up system did not always work when tested at minimum speeds.
The Asiana crash left three dead and more than 200 injured.