if the halon extinguishes the fire but hydrochloric acid and the sulphuric acid in vapor form still continue to exude. if those batteries were stored in the front i'd be looking for evidence of that. those two gasses together could be deadly. >> in supplement to what david is saying, if it got into the e and e compartment, lower compartment that has all the avionics and so forth, that doesn't have halon to it. it has a system that automatically -- if it senses smoke it will reverse the air flow. now if the pilots put on their oxygen mask, the problem is if they don't recognize they have a toxic situation they might not go and select the emergency button which puts oxygen in their face at high pressure and may be sucking in ambient air. >> let me go to miles o'brien. what do you make of this theory? >> this theory is as good as any theory we've heard. and there's another thing, too. there was an emergency air in