First condolenses all round. There but for the grace of god go we all. Especially on the sh*tty days, whether we are PAX, Crew or Baggage handlers.
Doc, Ace,
Just to pick up on transmission times. I just don't know how fast the extended nosewheel strut would trigger the transmission, it could be as little as 1/10th sec. but probably not more than 1 sec. - help somebody here.
I also don't know exactly what the message actually contains - but my IT background tells me the following:
One of the slowest transmissions on the planet today is your handy, mobile phone, phobile moan, GSM, or Nokia/Motorola/Ericsson thingy. Data and things like that (SMS's, etc.) today usually still go at 9600 bps (bits per second). A character is basically 8 bits, but with control overheads lets be generous and call it 9.6 - so you get 100 characters per second.
If we now guesstimate that we need the planes ID or Flight number at 10 digits/characters, a Timestamp with date at another 10-12 characters worst case, or 5-6 best case, and a transaction type indication at another 5-10 characters. - OK lets say 30-50 characters or 1/3 to 1/2 second.
To whatever that turns out to be we now add 60 nanoseconds per 1'000Km of distance and 60 or 80 nanoseconds per switching station (and here we may need to guess a bit more). 2 switching stations is minimum (1 in LIN & 1 in CPH), if land lines are used, be mean and add another 5 that will normally take you anywhere in the world. So worst case use 2000km = 120 ns. + 7 x 80 ns. = 680 ns. That to laymen is around 2/3rds of a sec.
So the whole transmission, even if its at these slow speeds is in the 1-2 sec. range - even if it has heaps of addressing and packing information around it, to get it safely where it needs to go.
Personal gut feel says 2 secs. after liftoff CPH was processing the message.
Now calculate how far the plane travelled from the time the nosewheel strut was load free. I'm going to get this wrong so somebody correct my math - but here goes:
V1 speed ca. 200Knts = 400Kmh = 400'000m.p.h = 111 m.p.sec.
So 2 secs is anywhere between 100-300 meters depending on what is and what isn't on the ground - allowing acceleration or creating extra drag and friction.
Now how long was it from initial impact to building impact. The damage on secondary impact was high so - speed was also. From the shots I've seen that must have been the longest 5-10 secs. that none of us ever want to have to live through.
Captain you are so right - avoid it before it happens - your chances of very much influence once s**t has started is OH so low... How sad, what a waste... RIP
[ 11 October 2001: Message edited by: gofer ]