The change happened with last month update, the pushback truck is now selected based on the airplane ZFW rather the total weight when pushback is called. The change was suggested by users that loads the airplane later.
Obviously, we also changed the threshold parameters to be smaller, and with yesterday's update, we changed them to be even smaller, for the precise reason to allow some of the largest tow truck on 737s so, right now the conditions are:
- the smallest truck ( FSDT_Pushback_Small ) will appear if the airplane ZFW is less than 90.000 lbs OR the parking size is less than 12 mt. of radius.
- the mid-sized truck ( FSDT_Pushback ) with a towbar-less mechanism will appear if the airplane ZFW is more than 90.000 lbs ( but less than 180.000 lbs ) AND the parking size is bigger than 12 mt. of radius.
- the largest trucks ( FSDT_Pushback_02 and 03 ), one with a towbar, the other without, will appear if the airplane ZFW is more than 180.000 lbs AND the parking size is bigger than 12 mt. of radius.
Considering the empty weight for a 737-800 is 91.300 lbs ( 90.000 as a cutoff has been chosen for a reason... ), this means, if your parking spot is at least 12 meters of radius, you should have an EQUAL 50/50 chance of getting either the smallest truck with a towbar, or the mid-sized one without a tow-bar, because 91.300 lbs is inside a weight range that is valid for both.