Update passenger count when reducing ZFW/payload

....................................................................
CODES   PAX   CARGO   PTTL    UNDL    :
105     12    0       1866    0T      :

Using default CL60 airframe, requested 12 passengers (2100lb PAX + 660lb CARGO for 2760lb payload). Payload was reduced to 1866lb to make room for contingency and reverse fuel, but passenger count was not updated. A better way to lower the payload would have been:

....................................................................
CODES   PAX   CARGO   PTTL    UNDL    :
105     10    116     1866    0T      :

Now that passenger and baggage weight are finally separate items, implementing something like this should hopefully be feasible.

I guess the one corner case is the remainder when the airframe has zero luggage weight (do we keep an extra passenger with lower weight, or convert the remainder into cargo instead?) but that’s probably just a matter of deciding between the two?

Regards,

Tim

I guess the ultimate corner case would be: requested payload 230lb (175 + 55 for 1 passenger), actual reduced payload, say, only 3 pounds: should probably be considered cargo rather than lighter-than-a-newborn passenger? So there could be a threshold below which a partial passenger is converted to cargo, and above which it may be kept as a young or light passenger?

Then even with a threshold, if many passengers remain, even a passenger made 172lb lighter by payload reduction could still be counted as having all passengers being just slightly lighter on average?

So maybe something like:

{
    if (partial_passenger_weight < (threshold / (count_other_passengers + 1)))
    {
        cargo_weight += partial_passenger_weight;
        count_all_passengers = count_other_passengers;
    }
    else
    {
        count_all_passengers = count_other_passengers + 1;
    }
}

Just thinking out loud really :slight_smile:

Regards,

Tim

Any thoughts?

Regards,

Tim

Hi Tim,

I’m still a little undecided to be honest.

Until now, SimBrief has generally operated on the same principle as real-world flight planning software that it’s based on. Which is to say, all it cares about at the flight planning stage is that the maximum airframe weights are respected. Accordingly, it will simply reduce the payload value as required to respect the limitations, but it won’t make any decisions as to who/what needs to be removed to make that happen. Real-world, that decision is left up to load planning (or the pilots, depending) and happens much closer to departure time, whereas the flight plan is normally generated hours before departure. This is the same reason why the load sheet is normally a separate document and not included with the OFP.

In other words, the passenger count on the OFP should be thought of as the number of “booked” passengers, not a final load. But I also realize that having SimBrief take a more active role in reconciling all the load figures might be more convenient (especially in a flight simulation context), so I haven’t really decided yet.

For now, it’s worth mentioning that it will roughly reduce the passenger count if the passengers option is set to AUTO (but without handling any remainders). But if a specific number of passengers is set by the user (i.e. you set the passengers option to 12 instead of AUTO), that number will appear on the OFP as the number of “booked passengers”, even if the payload weight gets reduced.

Long story short, I don’t really have an answer yet. But this has been added to my list of future things to work on. :slight_smile:

Best regards,

Roger, thanks :slight_smile:

Tim