alan diehl, we welcome you to the program. it was daylight. the weather was mostly clear.hat do you focus on as you try to understand what happened to this airplane? >> well obviously there are three potential areas if you eliminate weather. you have to look at human error, mechanical problems and you can't discount some sort of criminal act, although i know everybody is downplaying that and, of course it is very strange. but this is such a high-speed impact, that's the thing that is so surprising the fact that they descended. well, you could have a minor problem and get busy and not tell the controllers keeping your speeds up over 500mph in the mountains, that is incomprehensible if you're actually in control of your own faculties and the aircraft. >> woodruff: why incomprehensible? >> well, i've had to make a force landing in the mountains, incidentally, judy, in a light plane the first thing you do when you get down below the level, you want the start slowing down to look for a place to set it down but it appears there was no indication of any kind of maneuvering. i kno

now i want to bring in alan diehl, author of "air safety investigators" and also matthew l. wald aviation expert and jim hall a former chairman of the ntsb and juliette kayem, and david soucie author of malaysian flight 370 and now, if someone is in the cockpit preventing him to getting in, would that be recorded somewhere on the flight data recorder? >> only in that if they put the code in, it is going to put in a buzzer, and the buzzer is going to ring for 30 seconds, unless something is done, and they would pick it up on the cobckpit voice recorder. >> i want everyone to pay attention to this, because it is a airbus safety video, and it talks about what we are talking about. take a look. >> on the code pad, he presses the emergency code and enters the hatch key, and the green code will flash indicating imminent unlocking. in the cockpit, the light will will flash continuously indicating imminent unlocking, and then the door will go into unlocking sequence for five seconds. the green light on the code pad remains steady. the open light comes on for five seconds during the

alan diehl is a former faa and u.s. air force crash investigator, also an aviation psychologist at faa headquarters. doctor, thank you so much for joining us. >> thanks for having me. >> i would like to start by asking you what are the questions at the forefront of your mind right now? >> well, why the system didn't catch the obvious flags. of course we really don't know, this is all very tentative data but he got through a lot of screening programs. i used to watch the lufthansa pilots train in phoenix and i know they were very heavily screened in those days. this was several years ago. but somehow, this guy and we know this can happen people, psychopaths, whatever, can conceal these problems. they are very skilled at doing that. and this guy somehow managed to do it. >> doctor as you know now investigators have discovered the note the doctor's note that this co-pilot had saying that he is quote, not fit to work. of course there is the doctor/patient confidentiality clause in all of those types of relationships. i'm gu

some of these images we're looking at easier to take but we appreciate your time this morningp alan diehl thanks, folks. >> let's get a check in on the markets just about two hours into trading. we're still in negative territory on the major averages but we are well off the lows of the session. some would say we're looking forward the flat line with the s&p down by just about 1.5 points right now. we saw, jon, the ibb, the biotech index, down nearly 5% yesterday, go into positive territory at least twice this morning. so it does seem like investors are starting to put a little bit more money back into the market although with some trepidation? >> yeah. we were down triple digits and now just about 21, 20 points on the dow. >> that's right. >> all right. well, should silicon valley still be on bubble burst watch? several successful investors are predicting a death for many of the unicorn private companies that have been garnering sky high valuations. some others say there is no bubble. venky ganesan is managing director with menlo ventures. we had an interesting discussion yesterday about

alan diehl, former ntsb investigator. he wrote a book, air safety investigators.ere terrific yesterday. let's start with the simple. what main question do you have today based on what we know? >> where is the flight data recorder. i understand they found the voice recorder. that data recorder will be the other key to solving this mystery. bill: the loss of oxygen has been suggested that perhaps that is a reason that explains why this plane went down. do you think we have enough information now to determine that? >> no. clearly there's several scenarios. that's one of them. the so-called payne stewart scenario. we seen this happen before in other airliners. we also know that there is an aeronautical directive on the airbus sensors that, they're called angle of attack sensors. in the past they have caused airbuses to start descending uncontrollably and the pilots had to disengage the computers. so there, everything is still on the table. remember, there is always four basic areas that air safety investigators look at at first. one is human error. two is mechanical.

alan diehl, thank you so much. >>> so to recap what we do know a new timeline has been pushilied by aof the last moments of flight 9525. there are also some new reports on the medical condition of co-pilot andreas lubitz. and lufthansa airlines is telling nbc it knew of no medical problems for lubitz. recovery efforts and search for the flight data recorder continue. >>> to air canada now. a flight skidded off the runway early this morning as it attempted to land in heavy snow at the international airport in nova scotia. that plane was carrying 133 passengers and 5 crew members. here's how one passenger described what happened. >> we were coming into land. there was a big flash. there was guys on that side of the airplane who said we cut off a power pole. that's what took all the power out in the airport. when that happened the plane just came down and went bang. >> at least 25 people were taken to local hospitals. only one of them remains hospitalized at this hour. >>> in other developing news less than three days left for the negotiators in switzerland to accomplish what has vexed t