You need to do what you can to get the child. You can call police and see if they will help track him down. Whether you rent a car and drive, or leave and then try to get him to comply, that is a hard question which you need to consider. If you are able to rent a car and drive and be safe, then this might give you more time to locate the child. After that you can file a motion to limit his time and for your costs.
I agree with my colleague. Assuming you have court orders re: custody/visitation, bring a copy of the order to your exchange and, if need be, ask to speak with the airport police, ask them for their assistance and file a report. If he lives local to the airport you are traveling to, similarly you can speak with the local police department. If you have a court order, that will help enforcement. Bring copies of your emails/text messages. I would text/email him before the exchange and explain to him, in no uncertain terms, that he is to comply with the orders. If he doesn't, and you are unable to get your child back, you would be advised to immediately file an ex parte request (emergency request), follow the requirements for service/notice of the ex parte on the father, and seek orders that the child be immediately returned to you, including language that any police or law enforcement officer with knowledge of the order take any and all steps necessary to take the child from father and return him/her to your custody.
In the future, perhaps booking an earlier flight so you have more options would be advisable.
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