You can also attempt to use this case law, it only allow for you waiving your right and in this case the officer claimed a family emergency and also being on vacation.
In Commonwealth v. Hightower 438 Pa. Super. 400 652 A.2d 873, (1995) In appeals from summary proceedings arising under the Motor Vehicle Code (Title 75 of Pennsylvania Consolidated Statutes) or local traffic ordinances, other than parking offenses, the law enforcement officer who observed the alleged offense must appear and testify. Unless the presence of the law enforcement officer is waived in open court by the defendant, the failure of the officer to appear and testify shall result in a dismissal of the charges.
That is a long shot, because there is no rules or guidelines for the initial summary hearing, these are for appeals and the local magistrates tend to use these rule due to lack of guidance otherwise.
But you can also try this one
http://members.aol.com/StatutesP1/42PA5553.html
They have 30 days to hold the hearing, so if the officer is not there you could trying arguing they are in violation of the about statue.
The down side to this, is the judge could order you to sit there all day until the officer shows or have you come back each day until he does show.
It could be worth your time to move ahead without the officer and argue for a dismissal due to lack of evidence, because there is a number of things the state must show in addition to the ticket to up hold a conviction and since the officer is not there to put this evidence forward, they can not uphold the citation.
Obviously the more you know about your rights the better you can do in situations like this.
I beat a ticket because two of the 3 officers did not show and the try pulling the continuance card and it argue against it and the judge agreed. and dismissed due to lack of evidence.