One of their Bonanza's (N75AT), gets picked up by my PiAware ADS-B receiver as a multilateration (MLAT) target on its usual run between KIAD and KFRG in the early morning hours.
Hopefully they've got a plan to either upgrade the avionics for that plane to include ADS-B Out, or they're going to have to substitute another aircraft at the beginning of 2020 when the ADS-B mandate becomes effective.