Even better; your pilots like working for you and what you offer in exchange - The way it should be to keep people - You dont need bonds. But they are a legal way of amortising costs if people leave - That should be the sole purpose of a bond. Unfortunately poor employers do use them as a tool to drive down terms. The worst place I ever worked at used a £25,000 bond for 5 years (not for me thankfully), hoping no-one could afford to leave the very poor terms. Dozens did leave, nearly all scarpering and giving two fingers up to the bond (successfully in the end, because the bond was demonstrably excessive). So what did that company achieve? - If they had added the training and productivity losses to the pay packages instead, they would have been better off and kept happy staff.
However, sometimes people have to leave good companies for life reasons (eg spouse relocation), so there needs to be an out for them, and fair bonds ensure they cover costs. They needn't feel bad about it.
A sure fire way of having resentful and poor performing staff is to make them feel they are trapped there.