I had been in NYC with my dad, flew back on 10 September. On 09 September, before I headed for the airport, we went to WTC, up to Windows on the World, did some shopping in the mall, the usual. I was 25, my dad was there on work, and it was great to be with him, getting to have a much nicer experience than my J1 student visa experience 5 years previously! He took a photo of me outside, I've a grumpy face on me because he was very annoying taking photos and they were always awful (my poor dad).
On 11 September I was back in work, and after lunch, one of my colleagues phoned me and said, 'were in you in the WTC when you were in NY?', I replied, that I had been, two days before, and he then let me know that a plane had flown into one of the Twin Towers. I remember we were really quite unconcerned initially, we assumed it was a small aircraft, and I remember saying as we gathered in our conference room watching it on TV, do you think anyone will be injured? (Sounds so ridiculous now, but we had no frame of reference for this, we believed the towers were so iconic and permanent, no particular damage was possible).
Suddenly, the first tower to collapse fell before our eyes and I can remember the utter panic - and only then did I think about my dad. I wasn't very concerned as although he was still in NY, he was not due to be anywhere near there. As it happened, he had left that morning, just as the attacks took place, on a train to Connecticut, and was unaware of the attacks until he got there. His work was with a university, and I remember talking to him the next day, when the rest of world was in complete shock and nearly at a standstill, and he said that apart from a few mentions, the work had continued as normal, they met their US counterparts, did some visits / tours, had a meal, all the normal elements of a working visit. I found that so strange at the time, wondering if they didn't care because it was New York and they were in Connecticut but I realise now they probably were in complete shock and didn't know how to process what had happened so just kept going.
I always think of the people I would have incidentally interacted with that day e.g. the staff in Windows in the World, and the possibility less than 48 hours later they might have lost their lives.