Hi, thanks for the feedback.
Currently this behavior is intentional, in the sense that SimBrief will increase the passenger count right up to the MTOW/MZFW. Even if the last passenger’s weight cannot be completely fit into the aircraft.
In other words, as long as the 6th passenger can be partially fit into the allowable payload, that passenger will be included in the count. If that passenger were not included (i.e. the load gets restricted to 5 “whole” passengers), your ZFW would have been arbitrarily limited to something like 2,145 kg.
The reasons for this are that SimBrief is not a load planner, nor was it originally designed with GA aircraft in mind. In an airline environment, the flight plan is generated hours before departure, while the weight and balance is done much later. With this in mind, from a fuel planning perspective, it’s better to over-estimate the payload and ultimately depart lighter, than the other way around.
Another thing worth mentioning is that by default, SimBrief always includes the weight of the pilot in the aircraft’s empty weight. So when it plans 6 passengers, it actually means there are 7 people on board. So if your aircraft has only 6 seats, I recommend either setting the max passengers to 5 in your custom airframe, or alternatively, keep it at 6 but subtract the pilot’s weight from the airframe’s OEW (which will result in more payload space).
I guess that none of this really answers your question of how to make everything “just work” in auto mode. Another option is of course to simply set a lower max passenger count in the airframe settings. For example, setting it to 4 will prevent the system from planning a heavier load than this, which should eliminate this issue for the most part.
Good catch, I think I’ll add payload restriction alerts to the top of the Flight Briefing page so they are more visible. Maybe in the next update.
Best regards,