stops circulation down in that compartment. if you did smell the smoke first thing would be to put on your oxygen mask which includes the goggles. you have to use a different mike switch on your yoke to communicate. it's a lot of confusion. >> as a pilot do you have an immediate sense of how serious the fire is? i know alarms are going off. but are they accurate in terms of how big the fire is, or do you just smell smoke? >> oftentimes you'll smell something. a lot of times with us it turns out to be something they're burning in the galley behind us. so we don't immediately jump to the oxygen mask. it could have been insidious, slowly seeped its way into the cockpit. >> mary, how effective are on board systems against fires? >> that's the problem. because of the crash of value jet flight 92 back in 1996 we have fire detection suppression equipment in the cargo holds of wide bodied planes and others.