WASHINGTON (CNN) -- If one hardened cockpit door is good, would two barriers be even better?



Many airline pilots believe the answer is "yes," and are hoping to reinvigorate efforts to require so-called "secondary barriers" on every commercial plane in the country.



Pilots praise the hardened cockpit doors mandated after 9/11, saying they have done as much as anything to protect aircraft from terrorist assaults. But planes remain vulnerable for short periods of time during some flights when pilots go to the lavatory, get meals or, on long flights, change out crews.



Currently, flight attendants sometimes block the aisle with beverage carts to prevent possible terrorists from rushing the cockpit. But pilots believe the barriers -- relatively inexpensive gates that would be deployed before pilots come out of the cockpit -- would solve that vulnerability.



"This is an absolute no-brainer," Capt. Bob Hesselbein of the Air Line Pilots Association said. "Of all the things we could do, the most cost-effective thing we could do right now is put the device in."



ALPA this summer published a position paper calling on the U.S. and Canadian governments to require secondary flight deck barriers on all airliners by January 1, 2010. The barriers would be designed to delay anyone trying to attack the cockpit by at least five seconds, giving pilots time to retreat to the cockpit, ALPA said.



Hijackers have attempted to gain access to flight decks on planes overseas four times in the past year, according to ALPA.



The airline industry has fought efforts to require the barriers, saying airlines should be allowed to decide for themselves if the barriers would improve security. The barriers would not be useful on short hauls where pilots don't ordinarily leave the cockpit, and the airline industry claims other layers of protection are sufficient on longer flights.



Hesselbein disagrees.



"You can never guarantee that you're going to have an armed pilot protecting that cockpit from inside that cockpit. You can never guarantee that you're going to have a federal air marshal, or federal air marshal team, in the cabin to defend that cockpit.



"But the secondary barrier, once installed, will always be there," Hesselbein said.



The government has classified the number of federal air marshals and armed pilots, but it is widely known that they cover a small percentage of flights in the U.S.



In a June 2005 report to Congress, the Transportation Security Administration said the barrier "appears to be a simple solution that offers greater security at a relatively low cost."



"Valuable time is gained in deterring the movement of an unauthorized individual towards the flight deck," the report said.



But the TSA recommended against mandating secondary barriers, citing "the costs of engineering and installation that would be incurred by the [airlines] to retrofit" aircraft. "The economic fragility of the industry due to increasing costs, including persistently rising fuel prices, makes this a decisive recommendation."



The Air Transport Association, which represents the nation's major airlines, said hardened cockpit doors and other measures provide effective security and that mandating other measures should not be done "in the absence of appropriate risk analysis."



Rep. Steve Israel, D-New York, said he is again introducing a bill to require barriers on passenger planes.



"Everybody recognizes the vulnerability," he said. "The airline industry recognizes the vulnerability and thinks that the federal government ought to pay for the secondary barriers. The federal government recognizes the vulnerability and thinks that the airline industry should pay.



"Meanwhile, for as long as the debate continues, the flying public is less safe." E-mail to a friend
Which industry fights mandatory secondary barriers? Do pilots support the mandation of secondary cockpit barriers? Who did the pilots praise? How many mandating secondary barriers do we need? What do many pilots support? Who recommends against mandating secondary barriers?
airline "yes," the hardened cockpit doors mandated after 9/11, saying they have done as much as anything to protect aircraft from terrorist assaults. two "secondary barriers" airline industry
question: Which industry fights mandatory secondary barriers?, answer: airline | question: Do pilots support the mandation of secondary cockpit barriers?, answer: "yes," | question: Who did the pilots praise?, answer: the hardened cockpit doors mandated after 9/11, saying they have done as much as anything to protect aircraft from terrorist assaults. | question: How many mandating secondary barriers do we need?, answer: two | question: What do many pilots support?, answer: "secondary barriers" | question: Who recommends against mandating secondary barriers?, answer: airline industry