Art it all depends on what the carrier chose to use as far as a carry-on baggage program under the new FAA Advisory Circular (AC) 120-27E.
If the carrier chooses to have a carry-on baggage program, average passenger weights go up. Here's what the AC says:
"b. The standard average passenger weights in Table 2-1 include 5 pounds for summer clothing, 10 pounds for winter clothing, and a 16-pound allowance for personal items and carry-on bags. Where no gender is given, the standard average passenger weights are based on the assumption that 50 percent of passengers are male and 50 percent of passengers are female. "
SUMMER
Average Adult 190 lbs
Average Adult male 200 lbs
Average Adult female 179 lbs
Average Child (age 2 to 13) 82 lbs
WINTER
Average Adult 195 lbs
Average Adult male 205 lbs
Average Adult female 184 lbs
Average Child (age 2 to 13) 87 lbs
Now if you don't have a carry-on baggage program which is what Piedmont and I believe PSA has this is the guidance from the FAA:
"a. An operator with a no-carry-on bag program may allow passengers to carry only personal items aboard the aircraft. Because these passengers do not have carry-on bags, an operator may use standard average passenger weights that are 6 pounds lighter than those for an operator with an approved carry-on bag program. See Table 2-2."
SUMMER
Average Adult 184lbs
Average Adult male 294 lbs
Average Adult female 173 lbs
Average Child (age 2 to 13) 76 lbs
WINTER
Average Adult 189 lbs
Average Adult male 199 lbs
Average Adult female 178 lbs
Average Child (age 2 to 13) 81 lbs
Here's the rule about on what is allowed on board and what isn't:
"b. An operator that has a no-carry-on bag program may account for a plane-side loaded bag as 20 pounds. To receive authorization to use 20 pounds as the average weight for a plane-side loaded bag, an operator should demonstrate that sufficient controls exist to ensure that passengers do not bring carry-on bags aboard the aircraft. An operator also should demonstrate that sufficient controls exist to ensure the personal items brought aboard the aircraft can fit completely under a passenger seat or in an approved stowage compartment."
And finally, here's the the FAA definition of a "personal item"
"25. Personal item. Items the operator may allow a passenger to carry aboard, in addition to a carry-on bag. Typically, an operator may allow one personal item such as a purse, briefcase, computer and case, camera and case, diaper bag, or an item of similar size. Other items, such as coats, umbrellas, reading material, food for immediate consumption, infant restraining device, and passenger assist/comfort animals and devices, are allowed to be carried on the aircraft and are not counted against the personal item allowance."
Pretty vague huh?
Hopefully this helps you see the difficulty of the new weight and balance program each airline was required to comply with.