Commercial Fixed Wing
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Deviation - Speed All Types; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Became Reoriented
Human Factors
We were descending on the KORRY 4 arrival to LGA. Earlier in the arrival; ATC had assigned us 310 KTS or greater and I as the Pilot Flying had switched the speeds to manual. After reaching KORRY; we were told to fly direct to DIALS for the Expressway Visual runway 31 and descend to 4;000. I dialed in 4;000; confirmed it with the captain; and selected Flight Level Change. It wasn't until about 8;000 feet that the captain noticed our airspeed had never been dialed back. To which he called out; 'airspeed'. I grabbed the throttles and thrusted them to idle and he instructed me to pitch up. I clicked off the autopilot and leveled off while he dialed back the airspeed to 250 KTS. To the best of my knowledge; we were at about 300 KTS when he first noticed the discrepancy. Once slowed; we continued the descent and re-engaged the automation. No notice was given by ATC regarding the incident and the rest of the flight continued without issues. In hindsight; what I should have done when given the instruction to descend to 4;000 was to first set the altitude; dial back the speed to 250; and then; once slowed to 250; select flight level change to begin the descent.
We were descending on the KORRY4. ATC assigned us best forward speed initially then 310 or greater and finally 300kts. Level at 10;000 ft. we were discussing some final thoughts on the Expressway Visual 31 as this was the First Officer's first time flying this approach. At this time ATC issued a descent to 4;000 ft. It wasn't until about 8;000 feet that I noticed the speed error.  I quickly instructed the First Officer to pitch up to the horizon while I dialed the speed back to 250 KTS after which we re-engaged the automation and continued our decent. The rest of the flight proceeded without incident. I did then recommend and discuss a better technique when in this situation arises again - dial in the altitude; then the speed and then when speed is reached; the desired descent automation.
Flight crew reported they failed to slow speed below 10;000 feet altitude.