Narrative:

On descent into memphis; we were instructed by ATC to descend to 10;000 feet and maintain 270 knots for spacing. After reaching 10;000 feet and 270 knots; ATC instructed us to descend to 7;000 [feet] and maintain our current speed. We immediately began the descent from 10;000 [feet] but then realized we were still at 270 knots. We asked ATC if they wanted us to maintain 270 knots below 10;000 [feet] because max speed below 10;000 [feet] is usually 250 knots. ATC said yes; they wanted us to maintain 270 knots below 10;000 [feet] for spacing. As we started the descent; we discussed this and thought it might be ok because other airports (such as hkg) give similar instructions on approach; and ATC often approves greater than 250 knots below 10;000 [feet] for performance considerations on climb-out. (Plus; the controller explicitly said that's what he wanted us to do.) however; after I thought about this a little more; I wasn't convinced that ATC was right and I believed the safest thing to do would be to slow down to at least 250 knots and just tell ATC that's what we're doing. At about that moment; ATC instructed us to slow to 210 knots; and the issue became moot. Nevertheless; once we blocked-in; I told my crew I would research this issue and get back to them. My research confirms that 250 knots was the maximum authorized speed at that point in our flight. I will therefore contact my crew and apprise them of this so that none of us make this mistake again. Unintentional non-compliance with an far. I will make every effort to review our company fom and the pertinent fars with greater diligence.

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Original NASA ASRS Text

Title: Air carrier flight crew was descending towards arrival airport through 10;000 feet. The Approach Controller issued a speed assignment of 270 knots and an altitude assignment of 7;000 feet. The flight crew accepted the clearance and maintained a speed of 270 knots below 10;000 feet in violation of a FAR.

Narrative: On descent into Memphis; we were instructed by ATC to descend to 10;000 feet and maintain 270 knots for spacing. After reaching 10;000 feet and 270 knots; ATC instructed us to descend to 7;000 [feet] and maintain our current speed. We immediately began the descent from 10;000 [feet] but then realized we were still at 270 knots. We asked ATC if they wanted us to maintain 270 knots below 10;000 [feet] because max speed below 10;000 [feet] is usually 250 knots. ATC said yes; they wanted us to maintain 270 knots below 10;000 [feet] for spacing. As we started the descent; we discussed this and thought it might be OK because other airports (such as HKG) give similar instructions on approach; and ATC often approves greater than 250 knots below 10;000 [feet] for performance considerations on climb-out. (Plus; the controller explicitly said that's what he wanted us to do.) However; after I thought about this a little more; I wasn't convinced that ATC was right and I believed the safest thing to do would be to slow down to at least 250 knots and just tell ATC that's what we're doing. At about that moment; ATC instructed us to slow to 210 knots; and the issue became moot. Nevertheless; once we blocked-in; I told my crew I would research this issue and get back to them. My research confirms that 250 knots was the maximum authorized speed at that point in our flight. I will therefore contact my crew and apprise them of this so that none of us make this mistake again. Unintentional non-compliance with an FAR. I will make every effort to review our company FOM and the pertinent FARs with greater diligence.

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.