B737 Undifferentiated or Other Model
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Communication Breakdown; Time Pressure; Workload
ATC Issue All Types; Deviation - Altitude Crossing Restriction Not Met; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Airspace Structure; Procedure
While on the KORRY 4 Arrival into LGA; the aircraft crossed 1000' high (at 11;000' MSL) passing KORRY (published altitude is 10;000' MSL). This was due to an un-executable clearance change given by ATC to cross BRAND (fix 5.3 NM prior to KORRY) at 250 knots. The Crew attempted to comply; but this was an un-executable clearance change due to speed; altitude; and distance limitations. Prior to being given said speed restriction at BRAND; the aircraft was established on the proper vertical path while complying with the previous ATC directed speed of 300+ knots (aircraft was established at 310 knots). The new clearance/speed restriction for BRAND was given approximately 10 miles prior to BRAND. Immediately after updating the FMC with the new speed and beginning execution to comply; the Crew recognized the aircraft going well above the required vertical path to cross BRAND at 250 knots; then cross KORRY at the required 10;000' MSL. The Pilot Flying made every reasonable attempt to slow the aircraft to meet the 250 knots restriction at BRAND and then cross KORRY at the published altitude. Due to ATC radio congestion; the Pilot Monitoring was unable to request for relief to either restriction. ATC needs to give clearance changes such as these well prior to the applicable fix and consider including relief to subsequent altitude restrictions is clearances are given late.
Pilot reported receiving clearance too late to comply with the speed and altitude restrictions given and unable to request relief because of radio congestion.