• This is a partial transcript from "Your World with Neil Cavuto," December 7, 2005, that was edited for clarity.

    NEIL CAVUTO, HOST: With me right now is aviation security expert Charles Slepian.

    Charles, I know you and I have talked many time over the years since 9/11, and you have never rested comfortably that another incident could never happen. Why?

    CHARLES SLEPIAN, CEO, FORESEEABLE RISK ANALYSIS CENTER: Because I think what happened on 9/11 really was unique to those circumstances.

    But what has been happening all along has been the threat of explosives. And we still have not been able to conquer that beast. We still are not comfortable enough to say that you can't get an explosive either through the security station or into checked baggage or put on board from the ramp side of the airplane.

    CAVUTO: But, when you get stuff through security — let's say you're waiting on line, you have got to take your shoes off and do all the nine yards. Is it tough to get explosives through that process?

    SLEPIAN: We have nothing at the screening station that will detect an explosive. We have weapons-detection systems there that detect metals. We have X-ray, which will show you a picture.

    CAVUTO: What about plastic explosives, any of those?

    SLEPIAN: But plastic explosives seem to get through all the time, when the General Accountability Office tests.

    CAVUTO: How do they look when they go through that X-ray?

    SLEPIAN: They usually put it through something in a shield.

    CAVUTO: Yes.

    SLEPIAN: You know, it looks like a film bag.

    CAVUTO: Right.

    SLEPIAN: And you see something, and it's got a lead plate in it. It comes out black. And the screener says, what do you have there? And he says, I have got a film bag. And, indeed, there's a film bag.

    And, frequently, they don't go beyond the film bag to see what else is in the container.

    CAVUTO: But, in other words, how do you trigger that on the flight, you know?

    SLEPIAN: Well, it can be assembled on the flight. And Richard Reid, as you mentioned before, was intent on setting off these plastic explosives in his shoe.

    CAVUTO: He has the thing in his shoe, right.

    SLEPIAN: Yes.

    CAVUTO: So, you're not quite saying when we're over the hump with this sort of stuff?

    SLEPIAN: Oh, I think that we have a long way up the hill yet to go.

    CAVUTO: What do you mean?

    SLEPIAN: We still don't have the capacity to determine whether or not we have got explosives going through the screening stations. That's the number one threat.

    CAVUTO: When you say through the screening stations, this is above and beyond the cargo thing, right?

    SLEPIAN: Yes. Yes.

    CAVUTO: All right. So, explain.

    SLEPIAN: And that's why we are now talking about backscatter machines to see through clothing, to see if an individual has explosives strapped around his or her waist.

    We're not doing that with every passenger. We're doing that principally with passengers who we have profiled to suspect that they may have something on them. So, we have the problem. We are still checking bags that are going through using a puffer machine or a sniffer machine.

    CAVUTO: Right. I have seen a lot more airports using that. What does that do? What does that thing do?

    SLEPIAN: Well, it swabs the top of the bag, the exterior of the container for a residue of an explosive.

    CAVUTO: But it puffs airs at passengers, too, right? What are they looking for us on our bodies?

    SLEPIAN: If there's a residue on your clothing it will detect it.

    But if it's not the work of a sloppy terrorist, if it's tucked neatly into the bag, and the bag is clean, that won't pick it up. And that's still the problem we have. That's the one that devils us.

    Now, there is equipment out there now that can tell you the chemical analysis of everything inside of a container, including a metal container. And some of it is now being used by the military. But it hasn't been adapted yet for the airports. It should be. It must be. That's where the focus has to be, because that's where the threat has always been.

    There's always been explosives. And we still haven't dealt with that problem.

    CAVUTO: I know another thing you said we haven't dealt with. A smart man named Charles Slepian told me this.

    It's not so much the planes within our domestic United States, but those coming in from other countries, where it's a bit of a crapshoot whether the security from that particular country is up to code. Now, Colombia, we know it is very good, that Alvaro Uribe, the president, is being really diligent about this sort of thing. But, others, it's a bit of a crapshoot, right?

    SLEPIAN: But, as good as we are, we still can't do it, so we really can't expect others to do it better. And they're not doing it any better.

    CAVUTO: What's the biggest thing we do wrong?