Widebody; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP)
Confusion; Situational Awareness
ATC Issue All Types; Deviation - Speed All Types; Deviation / Discrepancy - Procedural FAR
Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Clearance
Human Factors; Procedure
Directed by SOCAL Departure to maintain 280 KTS below 10;000 feet during climb. Verbally confirmed the clearance and complied with ATC instructions. Similar; on descent; instructed by Chicago Center to maintain 300 KTS until further notice. At 11;000 feet and cleared to 7;000 feet; queried ORD Approach Control as to the speed they wanted from us. Was instructed to maintain 300 knots until further notice and continue our descent; which took us below 10;000 feet at 300 KTS.Followed ATC instructions for non-standard speed below 10;000 feet; which we assumed was for aircraft separation during the climb and the descent.
Air carrier pilot reports of two instances where they were instructed to maintain a speed higher than 250 knots while below 10;000 feet.