Commercial Fixed Wing
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Situational Awareness
Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
General None Reported / Taken
Human Factors; Procedure
We were given instructions to descend via the KORRY 4 to LGA and were assigned a 290 knot transition speed. I programmed that speed and we managed the descent down to the bottom altitude of 10000ft. MSL on the KORRY 4. We maintained 290 knots in the decent until reaching 10000ft. when the managed speed changed to 250 knots. ATC then asked us if we were assigned a speed upon which we replied we were given 290 knot transition. We were then given a descent to 9000ft. and told the aircraft behind us was flying at a faster speed. We complied and continued to fly the RNAV Visual Runway 31. The airplane automatically slowed to 250 knots at 10000ft. MSL to comply with speed restriction below 10000. Proper action would have been to step down a level of automation and select 290 speed upon level off at 10000. It is very important to be aware of these speed assignments with respect to spacing on the arrival. It would be a good idea to brief any assigned speed and discuss the possibility of problems with the automation; especially at this altitude where managed speed automatically changes to 250 knots. Good communication; situational awareness; and close monitoring of automation is very important through all phases of flight.
Captain reported slowing down below assigned speed because aircraft automation anticipated for the 10000ft airspeed regulations.