Narrative:

During the approach we were above 10;000 feet and given an ATC clearance to maintain 300 KIAS or greater. A few minutes later; while still above 10;000 feet we were given another clearance to maintain 250 KIAS or greater. As we transitioned through 10;000 feet the captain interpreted the clearance from ATC as to maintain best forward speed. Once below 10;000 feet; we were descending through 9;000 feet and still flying 325 KIAS when the controller asked what our IAS was. Upon read back of 325 KIAS; the controller asked if there was any reason we were maintaining that speed. At that time the captain keyed the mic to explain the clearance and how he interpreted it. The controller responded with a speed restriction to maintain of 200 KIAS. Before handing us off to the next controller; he explained only the FAA administrator has the authority to assign an airspeed greater than 250 KIAS below 10;000 feet.after talking about what happened the captain and I both agreed that the last airspeed clearance verbiage could be cleaned up to eliminate the potential confusion for crews in the future. Another example of a poor choice of verbiage in a clearance given by lax ATC on our departure from lax was to maintain 280 or greater in the climb. We were climbing through 8;000 feet when ATC gave us this clearance. Overall I believe the captain should have known better; I as the co-pilot needed to speak up more and ATC's clearances need to be more specific when giving a clearance that breaks an far if pilots comply with it.

Google
 

Original NASA ASRS Text

Title: A DA-50 Captain descending into LAX on the RIIVR STAR misinterpreted ATC clearances for higher than charted airspeeds and maintained an IAS well above 250K below 10;000 feet. The First Officer; expressing timidity; failed to share his concerns and it fell to ATC to intervene. The Captain cited his misunderstanding of permitted ATC discretion with respect to maximum airspeeds below 10;000 feet.

Narrative: During the approach we were above 10;000 feet and given an ATC clearance to maintain 300 KIAS or greater. A few minutes later; while still above 10;000 feet we were given another clearance to maintain 250 KIAS or greater. As we transitioned through 10;000 feet the captain interpreted the clearance from ATC as to maintain best forward speed. Once below 10;000 feet; we were descending through 9;000 feet and still flying 325 KIAS when the controller asked what our IAS was. Upon read back of 325 KIAS; the controller asked if there was any reason we were maintaining that speed. At that time the captain keyed the mic to explain the clearance and how he interpreted it. The controller responded with a speed restriction to maintain of 200 KIAS. Before handing us off to the next controller; he explained only the FAA administrator has the authority to assign an airspeed greater than 250 KIAS below 10;000 feet.After talking about what happened the captain and I both agreed that the last airspeed clearance verbiage could be cleaned up to eliminate the potential confusion for crews in the future. Another example of a poor choice of verbiage in a clearance given by LAX ATC on our departure from LAX was to maintain 280 or greater in the climb. We were climbing through 8;000 feet when ATC gave us this clearance. Overall I believe the captain should have known better; I as the co-pilot needed to speak up more and ATC's clearances need to be more specific when giving a clearance that breaks an FAR if pilots comply with it.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.