Israeli authorities plan to issue a new anti-hijack identification system to incoming aircraft which they say is foolproof, but some experts are not convinced it will plug all the security holes on the horizon.
Starting next year, Israel will require pilots who fly to its airports to use the Security Code System (SCS), a local invention designed to ensure planes that have been commandeered for al Qaeda-style attacks are spotted in time.
Israel plans a trial run for the system, using a credit card-sized keypad, next month, in co-operation with five airlines from the United States, Europe and Africa. About 10,000 of the units will ultimately be issued, with Israel bearing the cost.
Pilots who fail the authentication test when they approach Israeli airspace will be denied entry. Should a plane go ahead, ignoring further warnings, Israel will consider it hostile and scramble fighter planes for an interception.
In the worst case, that could mean an aircraft is shot down. "You can't bluff this system," Dani Shenar, chief of security for Israel's Transportation Ministry, told Reuters.
"It provides a higher level of confidence that the aircraft is being controlled by the right people, which is a huge asset in terms of avoiding unnecessary security alerts." He said the system knows how to differentiate between "a classic hostage-taking hijacking and a 9/11-style hijacking".
Shenar and the company that developed SCS, Elbit Systems, declined on security grounds to give details of the technology and procedures involved. Several experts familiar with Israeli methodology say the system - also known as "Code Positive" - is based on the assumption that a hijacking will take place in one of two ways.
Hijackers could either kill the pilots and take control - as is believed to have been the case in the September 11 attacks on the United States. Or they could force pilots to issue a compliant response to the system in the hope of buying enough time to reach Israel and crash the planes into a target on the ground.
In the first case, the hijackers would fail the security check as they entered Israeli airspace, giving military authorities about 15 minutes to launch a response.
In the second, Shenar said, pilots would be expected to relay a "May Day" alert. He declined to say how they would do this during a hijacking. Omer Laviv, an aviation security expert with the Israeli company Athena GS3, said some pilots may be reluctant to signal their predicament.