I have detected an anomaly in the rules. The Technical classes are described as operating the ship's sensors (specifically the Communications officer seems to deal with sensors when it comes to using the teleporter, while the Navigations Officer uses sensors to detect space hazards, and the Technical Crewman does a little bit of both). This is odd, since none of these classes has the Science skill necessary to interpret Sensors. Only the Scientific Officers and Enlisted Men have the necessary skill, yet they lack the class bonuses to use sensors well.
So problem number one; You would expect there to be one single class skilled at using sensors in all situations, but what you find is different sensor uses are spread over multiple classes, none of which actually has the skill required to use sensors.
Moreover, both the Navigations Officer and the Communications officer have Contact as a secondary skill, despite the fact that this skill (at least as it is described in the book) has very little to do with the Navigation Officer's duties. Indeed, the description of the Science skill (interpreting sensor results) seems more applicable to the Navigation Officer (detecting space hazards).
The second problem is that, because the Scientific class skills are limited to the personal-scale, a Scientific character has little to nothing to do during a space battle. Their specialties are contacting alien life and treating the wounded, neither of which are a part of the battle (although they may be important before or after the battle). Where the Technical classes can busy themselves operating the sensors during the fight (something which should arguably be a Scientific class job), the Scientific characters just have to sit on their hands.
I am not sure exactly how to address these issues. I would probably recommend at least changing the Navigation Officer's second skill to Science (Contact seems useless for him). Otherwise, the Contact skill should be expanded to cover both diplomacy AND sensor operations, while the Scientific skill is narrowed to analyzing data that the computer sensors cannot interpret (so that a sensor operator would mainly be using Contact for their duties).
A bigger change might be to fold the Medical Officer and the Biology Officer into one and add the third Scientific Subclass of Physicist (with class abilities for using the Science skill to understand bizarre cosmic and physical phenomena). This might make sense, since McCoy often analyzed of alien flora and fauna, despite being just a medical officer ("Damnit, Jim!").