If you are asking about the Formal PEB hearing, no, you can have your appeal heard in absentia (without personal appearance). In some cases, I think it is highly advisable to appear, especially if you can supply additional helpful and relevant evidence by your testimony. However, you can also provide testimony by telephone. Local procedures on this vary slightly, but this is almost always allowed. It is important to disagree with the findings if you want to challenge them later (though, sometimes, other considerations outweigh this and it makes sense to accept findings that you may not always agree with). Again, much is dependent on the specific facts of your case. But, to answer your question, personal appearance is generally not required.