The use of box cutters was key to the 9/11 plot’s success as they were easy to carry on to domestic flights in the USA undetected, but deadly and threatening enough for determined hijackers to subdue passengers and gain control of an aircraft. 

It was me, Anthony C Heaford, who told Khalid Sheikh Mohammed’s terror cell that hijacking a plane with box cutters was a viable attack method. I had first perceived of a 9/11 style attack on the 11 June 1997 whilst on a flight from Logan airport Boston to Toronto Canada, as detailed here, and I gave my first warning about such an attack on 12 June in Toronto, as detailed here.

Three months after I had warned of a 9/11 style hijacking my employer sent me to install a machine in Yemen, in a factory that turned out to be Khalid Sheikh Mohammed’s terror cell’s front company, as detailed here. During that visit a Pakistani machine operator I was training asked me about visiting New York as a tourist and I repeated the 9/11 style attack warning I’d given in Toronto in June. The next day the other Pakistani machine operator I was training asked me about my warning, a conversation I outlined here, but without the level of detail I am now providing below.

In my conversation with the first machine operator on 22 September 1997 I had very specifically said that hijackers could carry Uzi submachine guns on to a flight from Logan airport because when I’d passed through Logan airport on 11 June 1997 there were literally no security checks. The next day the second Pakistani machine operator confirmed the travel warning I’d given his colleague before asking me the following questions:

Question: What if the hijackers couldn’t smuggle firearms on board?
I pointed to the box cutters in my tool case, said that I had accidentally carried them on at least two domestic flights in the USA without being stopped, and said they were enough to hijack a plane.

Question: How could you hijack a plane with box cutters?
I said that I worked with box cutters almost everyday as part of my job but that I was still ‘terrified’ of accidentally slicing my hand or fingers each time I used them. I speculated that holding the blade of some box cutters to a cabin crew member’s throat would be enough to subdue the passengers and take control of the aircraft.

Question: What if the passengers resisted?
I explained that certain flights (planes repositioning, etc) had minimal passenger numbers and describing the layout of a plane’s seating I said the passengers would only be able to resist a hijacking one at a time because of the width of the aircraft aisles.

Question: What if the passengers were able to overcome the hijackers?
I said that so long as the hijackers had managed to take control of the cockpit, then the plane would still likely crash and from a hijacker’s perspective that would still be a success.

Question: Where would they put the bomb?
I looked at him with frustration and said the plane - a fully fuelled large passenger plane - was the bomb.

Question: Do you think a plane could knock down the a World Trade Center tower?
I said I had read (after the 1993 WTC bombing) about the flimsy construction of the towers and that the impact of a large plane traveling at hundreds of miles per hour would likely demolish a tower, but even if it didn’t the ‘terror’ aspect of a civilian airliner striking the most prominent buildings in the world would still be considered a ‘success’.

Those are all the questions I remember - a conversation of a few minutes - and the machine operators did not raise the topic again. Why did I give such a detailed description of such an attack?

1. The customer in Yemen had purchased a machine made in Manchester England at a trade show in Chicago via a purchase agent based in London - to my mind this made them ‘allied’ to the West. I could not conceive that enemies of the West would operate in such a way.
2. The two Pakistani machine operators told me they were chemical engineering graduates, and as they were working overseas for a prestigious company as I was, I considered them equals.
3. They had asked me about visiting New York as tourists - my description of such a hijacking was not a plan, it was a travel warning. I told them that if they were hijacked in the USA that they should resist the hijackers due to the likelihood of it being a suicide attack.
4. They challenged the validity of my warning with their questions. I guess my detailed description of how such an attack could succeed was a matter of pride, to convince them of the very real danger of such an attack.

Did I repeat the detail of box cutters to anyone else? No. Despite giving my first 9/11 warning on 12 June in Toronto and again during a business trip to Brooklyn New York in December 1997 I did not say I had accidentally carried my box cutters on several domestic flights. I left out that detail for selfish reasons - I did not want to highlight that I had unintentionally broken the law and therefore risk losing my ability to fly to and travel in the USA. I did intend to tell the authorities about the box cutters and that’s why when I gave my warnings in Toronto and New York I very specifically asked the people I warned to get their security services contacts (which both men said they had) to contact me. I thought that telling security officials directly about my accidentally carry box cutters on board domestic flights would be better than a third party telling them.

I was never contacted by the security services so I never had chance to give them a piece of detailed information that could have / should have ensured that a) the existing US law that small knives could be carried on US domestic flights would be changed, b) airport security could be warned to lookout for boxcutters in hand luggage, and c) aircrew could be warned of such an attack method and cockpit security could be improved.