Washington ( CNN ) -- Fire-protection systems on freight aircraft are inadequate , top U.S. aviation investigators say . The National Transportation Safety Board recommended improvements and rule changes Wednesday based on investigations of three catastrophic cargo plane fires . NTSB Chairwoman Deborah Hersman recommended that the Federal Aviation Administration require better early detection of fires inside cargo containers , development of fire-resistant containers and requiring active fire-suppression systems on all freight airlines . An NTSB report focused on three cargo fire accidents since 2006 . Two of those fires killed the flight crews and destroyed the aircraft , in incidents in Dubai and North Korea . In the third incident in Philadelphia , the crew escaped with minor smoke-inhalation difficulties , and the plane was significantly damaged . `` These fires quickly grew out of control , leaving the crew with little time to get the aircraft on the ground , '' Hersman said in a statement released with the report . `` Detection , suppression and containment systems can give crews more time and more options . The current approach is not safe enough . '' FAA budget cuts would affect fliers . In all three cases , the fires started within the cargo containers aboard the planes , but by the time the plane 's fire warning system alerted pilots to the dangers , there was little time for them to react . Federal regulations require cargo airline fire detection systems to alert pilots within one minute of a fire starting , but the NTSB 's investigation found current systems detected fire and smoke anywhere from two and half minutes to more than 18 minutes after the fire started . The NTSB concluded cargo containers made of flammable materials significantly increase the intensity of the on-board fires because there 's been little focus by manufacturers or regulators to develop fire-resistant cargo containers . Additionally , the NTSB 's report recommended improved fire suppression systems on cargo planes , a recommendation it originally made to the FAA in 2007 . After the 2007 recommendation , the FAA did a cost-benefit analysis of upgrading fire suppression systems and found it to be too expensive , a fact the NTSB highlighted in its report . `` The two catastrophic cargo airplane fires that occurred in less than a year occurred after the FAA 's cost-benefit analysis concluded that the installation of fire suppression systems was not cost-effective , '' the board said . UPS briefed Hersman earlier this week on the shipping company 's efforts to develop improved fire safety standards . Also , FedEx is in the process of installing a fire suppression system on its long-haul fleet , the NTSB said . In an e-mail statement to CNN , FAA officials said the agency `` has long supported improved fire protection on all cargo airplanes through research on new , non-Halon fire extinguishing agents , fire suppression systems directed at individual cargo containers or specific cargo compartment zones , and advanced cargo containers incorporating smoke detection , fire containment , and/or fire suppression systems . '' FAA officials said they would carefully evaluate the NTSB 's recommendations . Way beyond air bags : NTSB wants next-generation safety devices on cars , trucks .
`` The current approach is not safe enough , '' the head of the NTSB says . In '07 , FAA said fire-safety upgrades too expensive based on cost/benefit analysis . NTSB : Industry has focused little on developing fire-resistant containers . *