An attack by a co-pilot on the captain of Flydubai flight FZ 1073 has raised concerns about cockpit access rules after passengers helped an injured pilot keep the aircraft from crashing. The Dubai-to-Tel Aviv service was carrying more than 170 people, most of them Israeli. The stabbing appeared to be an effort to bring down the plane, but the motive remains unknown as an investigation begins.

The incident has drawn attention to cockpit doors that can be secured from within, a safeguard introduced after the Sept. 11 hijackings in the United States. Experts differ over the policy, which is intended to keep intruders out but can also prevent access during a threat inside the cockpit. More details are expected as the story develops.