I went back and reviewed the key language in the regulations, §89.501:
(c) Except for unmanned aircraft designed and produced to be standard remote identification unmanned aircraft, this subpart does not apply to the design or production of:
(3) Unmanned aircraft that weigh 0.55 pounds or less on takeoff, including everything that is on board or otherwise attached to the aircraft.
Note the bolded italics above. The reg, as written, arguably has some ambiguity.
On the one hand, the first clause strictly interpreted, would seem to imply that any drone, regardless of size and weight, must broadcast RID if they have it built in.
The second highlighted clause seems to imply that if a drone weighs less than 0.55lb AT TAKEOFF it is exempt from RID broadcast. This also seems to be the way the industry is Interpreting it.
Add to this the fact that sub 0.55lb drones are not required to be registered with the FAA elsewhere in the regs, combined with the FAA seeming to ignore this ambiguity leads me to strongly conclude that standard remote identification aircraft are not required to broadcast RID if, at takeoff, they are under 0.55lb.
In an actual legal hearing, the construction of section (c) would generally defer to para (3) as clarifying detail for the section.
All that said, pilots need a way to enable RID when flying with the lighter battery and other attachments. I predict we'll see this switch in the next version of Fly.
