Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 228; Flight Crew Type 6000
Communication Breakdown
Deviation - Speed All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert
Human Factors; Procedure
On the ZZZ Arrival; we were told 'maintain 250 knots;' then it was reduced to 230 knots. This resulted in us being slightly high on the arrival and approach. All altitude restrictions were at or above. As the Pilot Monitoring (PM); I acknowledged another speed assignment of maintain 180 knots until ZZZZZ fix; cleared for the approach. The Pilot Flying (PF); two miles from the fix; slowed to 145 knots to prevent being high and fast. So; he chose to slow then descend fully configured to correct to glidepath. We did not inform the Tower of the speed deviation. Tower called out traffic just prior to the fix and then asked our speed. Due to the traffic call just ahead; we had thought he was going to say we needed to slow but when I told him we were at 145 he told us we were in non-compliance of the speed restriction. Due to safety reasons; we slowed to comply with our stabilized approach criteria but we did not coordinate that with Tower.
[Report narrative contained no additional information.]
Without informing ATC; B737-700 flight crew slowed below last assigned speed in order to descend fully configured in a stabilized approach.