Mark,
I agree with you on two points. I assumed that there was an employment contract, but in fact it does appear that it is at will, and I further agree that your hypo introduces a change of circumstances, that is further consideration, as you suggest, and will support the new training contract. However, in your hypo, the situation has changed due to an external circumstance, a factual impossibility that impairs performance, that neither party could foresee or control, and consequently requires both parties to make adjustments, and agree on them, in order to continue onward in the relationship. Going forward, there will only be a jet flown with the company, and no more props, for example. But, this terminates the prior agreement, and requires both to renegotiate. In the current post however, the pilot is being asked to do the same thing before and after, he has not agreed to do anything differently, except suffer additional detriment, but only at the prospect of being fired. If he were allowed to continue in a similar role not requiring training, or in a perfect world, not take the job in the first place (if the training contract were offered at hiring as it should have been), he would have free will, the basis for contracts, and the contract would be valid. The pilot in this post, is being asked to promise that he will do something further, based on past performance, training that he has already recieved. Past performance is not valid consideration. In your situation, the obligations have changed as per a new set of circumstances, after the original agreement, sufficient enough for you to argue that positions have been changed in reliance, hence they both suffer a legal detriment. The pilot is being asked to do something different, fly another jet, or pay back his costs.
Furthermore, aside from the consideration argument, I would argue that the real contract in the post is void, if it is not delivered at a time concurrent to the initial hiring (whether non-compete, or other condition that employment is subject to), and that means usually within days of signing on with the company, if not sooner. That seems to be supported in a majority of states. And finally, I would still assert that this employee had significantly performed in reliance of the original agreeement (that did not require the detriment in the form of reimbursal), and it is likely that he did not freely bargain for the second agreement, hence he signed under duress. He may have been worried that despite good performance with the company, and good standing, his job will be in jeapordy if he does not sign it, hence the only reason that he would sign, is to preserve his job. The failure to sign the agreement is a valid reason for not continuing the hiring process, but not for firing an at will employee, who is otherwise performing congruent to the arrangements at the time of hiring. I fully believe that my argument would suffice, even in light of an at-will arrangement.
To offer a contrary hypo to explain, Scientist X is regularly working in an at-will environment, on projects that don't require a confidentiality agreement. X's boss comes in and says, we are starting work on a new project (that he has never worked on before), and if you choose to partake in it, we must have you sign a confidentiality agreement. If the employee says, I don't want to, the company will keep him on the existing projects, or fire him, but it is likely that they would not have offered him a new project if he were truly a poor employee worthy of firing. So, he can stay, but, remember, he has made the decision prior to the new performance. If this Part 135 training agreement were offered before the training, but the pilot were allowed to continue in a flying role that did not require the new training should he elect not to sign the contract, I think it would be upheld as a valid contract. Otherwise, I would argue that the pilot, if fired, were entitled to at least damages shown in reliance with the first agreement. Back wages, moving expenses (if employment had just started), etc.
So, as I said before, no one is really right, until the trier of fact decides, but I definately think, on the limited facts, that he has a case. Problem is, I don't know all the facts yet. So, this is all conjecture.
CB