welcome back. the downing of flight mh-17 has many wondering if anything can being done to protect commercial planes from missile attacks. and a number of things are being suggested. our brian todd talked to a weapons expert and found out that technology exists to do this to passenger jets, it s just not all that practical. reporter: as crews cysift through the wreckage of flight mh-17, pressure is mounting for this u.s. senator mark kirk is worried about the safety of american passengers, calling on the faa, quote, to install counter measures on commercial planes. those systems could have prevented this, a november 2003 attack on a dhl cargo plane over baghdad. it managed to land safely.