The decision should be a 'guideline' left to the crew to determine after assessing each situation. (This is assuming the laywers are letting them in the vehicle in the first place)
If the child is easier to assess and manage with the parent there, then they should go, and be in the compartment with the patient.
If the child is more upset with the parent there or if the parent is too emotional and not easy to control then they need to ride up front, or not at all.
Critically ill kids tend to be unconcious so their emotional state is not the concern. The issue becomes with what Eric mentioned; what if the child has a poor outcome? One train of thought says "Let the parent see it all so they can know and understand that the crew was competent and caring and all that could be done for their little one was done." This is a huge part of the grieving process. This may not be physically possible depending upon space and configuration of the vehicle. An advantage of ground transport is that we can stop and remove the parent from the area if need be. I don't fly much, but asking a parent to leave the helicpter may not go over well with the bosses.
Note: I have a lot of experience with this and I've found that talking very straight to the parents and setting ground rules prior to leaving the facility avoids many headaches down the road. A conversation may go like this. "You're little boy/girl is very sick. This transport carries a lot risks with it, but he/she needs resources that just aren't availble here. You may ride with us in the back of the ambulance, BUT, if your child becomes unstable during the trip, his/her life depends upon you staying out of our way and listening to every word we say. Do you understand this?" Then follow it up with something a bit more lighthearted if you feel the situation warrants it. You didn't catch the social worker part of the job description when you signed up, did you?
This is why crews need to be well trained and adapt to each patient and situation accordingly. I don't know if this helped answer your initial question.
One more note before I get even more long winded. Some kids out there have some exotic stuff going on. It's impossible to be an expert at everything. Parents know their kids better than anyone. Use them and their info.
P.S. DVD players are an absolute godsend in pediatric transport. Spend the money. It's well worth it! SpongeBob is better than benzos!
We are 100% pediatric, and we try to take a parent along of at all possible on all 3 modes of Transport. On ground, we have hem ride up front almost all the time. We, too, have found that the patient becomes more calm more quickly when you separate them from the added emotional stress that the parent usually brings along. Baring physical or emotional limitations, I could not, however, understand why a program would not allow the parent along. On rotor, we take them if they can deal with it emotionally, can speak and understand English, and we have the capability to carry the added weight. On FW, the same applies.
On more than a couple of occasions, I have transferred care of the child to the receiving unit and the child has died soon after. How would you not allow the parent to be there for one last kiss or to say goodbye. Our program and health system is very focused on family centered care. This involves having the patient's primary caregiver around as much as possible.