Originally Posted by daOldMan

Some airlines have a box that you will need to check that asks you if you have ever started training at a 135/121 carrier and did not complete it. Personally, I started with a 135 outfit about 25+ years ago, and the job went away before I finished training. I have had to check yes to that box, and I think it did hurt me. I had to explain my way out of it a few times.

In other words, many companies offer you the option to quit during training rather than being fired. If you leave during training, it may look like you were not cutting it and were asked to quit. In the end, it can hurt you down the road if you quit during training.