If this is a generic, "what if I can't make it to work, if....." question, than the answer is just get out in front of the problem and contact CRS asap so you don't create a bigger problem for the company. Sh** happens all the time, and some could have been avoided with being less optimistic about getting to work and some is just, well, acts of God. Don't sweat it, this happens way more than most of us know. Just don't be the guy who had a scheduled DH to Europe and planned to show hours before the operating leg, lied about being in position to VIPS, and now is stuck somewhere because his commercial flight failed to get him where he expected. If you did the right thing in trying to get to work, had some plan B, and still couldn't make it work, you will be all right. Will probably still have a letter in your file, but it will go away. Just try not to let this happen anytime soon after wards.