Armed sky marshals and bullet-proof flightdeck doors are two of the solutions being urgently considered

US airlines, manufacturers and the Air Line Pilots Association (ALPA) are working with the US Federal Aviation Administration and Department of Transport (DoT) on an urgent programme to develop and implement enhanced security measures, including bulletproof flightdeck doors and bulkheads and on-board armed "air marshals".

On 16 September Transportation Secretary Norman Mineta established two rapid response teams made up of representatives from the industry to work on improvements to national aviation system security. One is focusing on aircraft, the other on airport security. Both must report by 1 October.

ALPA president Duane Woerth says the priority is the armoured flightdeck door - an idea which the pilot's union had previously opposed. Woerth says: "I want a certification process approved by the FAA, the manufacturer and ALPA." Industry vendors in several countries, including Israel, the UK and the USA are considering partnerships in view of the sheer scale of the prospective retrofit market.

United Airlines began the process within 48h of the attack, asking suppliers for immediate solutions that could be implemented within 30 days, and longer-term security solutions involving more significant redesigns of bulkheads, doors, forward fuselage interiors and cabin systems. The FAA is expected to issue emergency airworthiness directives to support the action.

Known vendors of armoured or strengthened doors include the Israel-based suppliers of double doors to El Al, and a UK company that provided titanium cockpit doors for Swissair Boeing MD-11s designated to carry gold bullion. The Swissair aircraft also had cabin cameras fitted among several other security measures. Flight Structures, a B/E Aerospace company in Arlington, Washington, also supplied Kevlar-based bullet-proof flight deck doors to South Korean airline Asiana.

Although the 11 September terrorists used knives and cutters as weapons, the barrier is "...not to stop the hijacker's bullet, but the bullet from the air marshal". The team is considering weaponry for pilots as well as providing armed air marshals for flights - the FAA is already advertising to recruit them.

Short-term fixes being studied within the industry include the attachment of composite or Kevlar cross-weave layers to flightdeck doors and bulkheads. Longer term solutions under study involve totally redesigned bulkheads, El Al style twin flightdeck doors and built-in cabin security cameras.

Certification concerns include depressurisation vents in the doors, and the use of Kevlar and other bulletproof composites in a cabin environment. Aside from additional weight and consequent payload loss, the airlines face the high cost and disruption of the retrofit.

Source: Flight International