a jury our that will not take into consideration his service, respect, familiarity and expertise in the area. his testimony was compelling but may fall short of what zimmerman need to counter the emotional testimony of trayvon martin s mother. the truth, so help you god? yes. you heard screaming or yelling, do you recognize that? ? yes. who do you recognize that to be, ma am? trayvon martin. he considers george zimmerman his son. unlike trayvon martin s mother, he is not family. very close friend. he was able to tie didn t tie the voice on the call and screams on the call, i am not sure if the jury is really going to believe 100% that he can actually identify george zimmerman s voice screaming. reporter: the court has heard from zimmerman s mother and uncle. and john don leap was not the only zimmerman friend testifying he could hear his voice. a body of opinion for the jury
how do you open that? okay, did you look at your briefing card? do you know how the exit opens? i don t know. did you know there was an exit behind you? no. reporter: in 20 second i made three common mistakes that could me and others killed. in little rock, 134 out of 135 people surp vifd. including one man who scrambled out with the seat still on his back. he crawled away from the airplane. it wasn t up tintil he got to t area he realized he hadn t unfastened his seatbelt. when it is taking off and landed. if you do that, and there is an if pact on takeoff or landing. having it belted tightly will keep you from being thrown around. the seat absorbs much of thenner jeep of the impact. minutes after the asiana flight 214 crashed, first responders rushed to help. they saved a lot of lives.
who yelled for help on the 911 call is truly at the center of the trial, center of guilty or innocent or guilt yef verdict. a parade of witnesses, friend of george zimmerman s testified it was george zimmerman not trayvon martin yelling for help on the tape. do you know whose voice that is in the background screaming? yes, definitely. georgie. i thought it was george. george zimmerman s voice. can you identify whose voice that was yelling in the background? george s. how do you know that? i recognize this voice. i have heard him speak many times. i have no doubten ein my mind that s his voice. one witness may have been more significant than any other. our david mattingly reports. reporter: after two weeks on trial for second degree murder, george zimmerman found a friendly ear in more ways than one. the voice screaming on the
tape is absolutely george zimmerman, sir. reporter: john donly, a long time close zimmerman friend and also a former vietnam vet, a combat medding with experience identifying screaming voices. you know the men you are with. you know the men that you eat, sleep with, you know who it is going to be before you get there. you can tell that from hearing their voice screaming for help and comparing that to what you heard in your everyday life with them? yes. reporter: when he turned his ear to the screaming on the 911 tapes. donley testified he heard a familiar voice. that is george zimmerman. and i wish to god i did not have that ability to understand that. reporter: who would begin to question his credibility with screaming men and how they may scream at different pitches. even the heough he has no sigh tiffing training i can t imagine
reporter: we got exclusive access to their training center in 2009 and spoke to nora marshal who led the human performance and factors di vgs of the ntsb. tell me about it and how you want you - tell me about the myth and how you will disspell it. these days one key roone you can make it out. equipment enhancements. we have improved the chance of survival by improving seat strength. by building airplanes that can with stand crash forces. reporter: fake a look at the inside of the asiana plane. damaged seats could protect passengers. another example. little rock, june 1999. landing in a thunderstorm, american airlines flight, 1420 slide off the run way. if pacts a light structure. splits open. fire breaks out. with the fuselage breached. much of the cabin destroyed. many seats remain in tavenlgt even some ripped out by impact.