Large Transport
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 6
Communication Breakdown
ATC Issue All Types; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Separated Traffic; Flight Crew Returned To Clearance
Procedure; Human Factors
[Aircraft X] was on the ATL 26R ILS approach; assigned 180 knots to the FAF. [Aircraft X] slowed well prior to the FAF. The monitor caught the speed reduction and was able to speed him back up to the assigned speed without loss of separation.  I was not working the position; but witnessed the event. The controller made a great catch on this. Separation could've been lost behind Aircraft X.  Please share this report with anyone you see fit; especially [Aircraft company X]. Advise [Aircraft X] company that any 'wink-wink deals' they made with A80 dealing with speed are now null and void and that all [Aircraft X company] aircraft must adhere to ATC clearances as every other user in ATL has do. This must cease.
Shooting ILS 26R at ATL; controller cleared crew for approach and ask us to maintain 180 knots to AJAAY (FAF). Aircraft slowed at approximately three NM from FAF to ensure proper configuration for ILS (not a visual approach) approach per the FOM. Just outside AJAAY; the controller asked us what our airspeed was and was upset that we had slowed below 180 prior to AJAAY. Inside the FAF; the controller gave us phone number to ATL Approach facility and asked us to call for possible deviation/violation.
A80 Controller and pilots of aircraft report of a speed reduction on final that could have led to a loss of separation. Final monitor caught the aircraft slowing and issued speed again for it to maintain. Pilots slowed aircraft before final approach fix as per their flight manual.