BBC News World America Eyewitness
As one of the lucky survivors of the WTC tragedy, I feel I have to convey my thoughts
We (a colleague and I) flew into NYC on Monday evening for a range of client meetings on Tuesday - the first being 8 am, Tower 2 WTC.
We were on the 72nd floor of WCT2 when the first plane hit tower 1. We heard the bang, and saw debris, and thank god, the client that I and my colleague were visiting had the sense to realise what was going on and told us to get out of the building. We were not so "street wise".
'The whole building rocked'
We walked down the stairs - 72 floors seems like one hell of a long way to have to go - afraid, but not really sure why - we really did not know exactly what had happened
The evacuation was very orderly, people were great - no panic.
As we got to around floor 50, a message came over the tannoy, telling us that there was an isolated fire in tower 1, and we did not need to evacuate tower 2. Again, thank god we continued down, others didn’t.
As we reached around floor 38, the second plane hit - the whole building rocked, I guess like a building must shake in an earthquake - although we had no idea what had happened.
We were, in fact blissfully ignorant as to what was going on - and because of that, other than momentarily, no one panicked - if we had known what I later saw on TV, I fear things may have been very different.
'Once out of the building, we ran'
As we eventually reached the lower floors - there was a greater sense of urgency - clearly people at the bottom knew what had happened. People told us to get out of the building. People began to run, the feeling changed, people were clearly more scared, not least because we feared the risk of being hit by further debris falling from above.
Even then, we had no idea that a second plane had hit our tower - (although there was already speculation that the first explosion was a plane - people around me were assuming an accident.)
Once out of the building, we ran - not sure where, but to what we thought was relative safety. We stopped to catch our breath, and after 5 minutes or so, tower 2 collapsed - we heard the noise, saw the smoke and dust, and ran for our lives again.
We escaped - we were very lucky - many many others, I know were not so lucky.
As we ran, the vivid picture of streams and streams of firefighters travelling towards the scene will stick in my mind, I think forever. Even then, we knew that as we were escaping, they were heading straight towards a total disaster area.
I think even then, we realised that many of those men and women would probably not return from the scene alive.
'I am lucky - others are not'
Only when we returned to Manhatten in the evening did we stop to see TV pictures - and only then did it really begin to sink in - the enormity of what had just happened.
We were still high on adrenaline, and trying to be very resolute, but waking up the next day, the real sense of what had happened hit. And the real feeling of sadness - for those who did not get out alive, and for those rescue workers, who basically gave their lives to save many, many people.
I will never forget the 11th September 2001 - the feelings - the mixed emotions of euphoria at being alive, followed by immense sadness for what has happened. And still it is not over.
It is almost impossible to stop replaying the scene - with different scenarios - each time I have a realisation that we were so so lucky - and that things could so easily have been different.
I am also amazed by the calmness of the individuals who evacuated with us, and in awe of the efforts of the emergency services, right from the start.
I am lucky - others are not, and my heart goes out to the families of each and every person who has not made it through this most horrendous experience.