Narrative:

Our ATC controller advised us of opposite direction traffic climbing to FL210 at our 10 O'clock position at 4 mi as we were descending through FL230 for FL220. I observed the other aircraft pass on our left from our 9 O'clock to our 8 O'clock position and reported to the controller that we had visual contact with the aircraft passing on our left. The controller then stated that the other aircraft was climbing to FL210 and that when clear you will be cleared for the civet profile descent to lax runway 25. I answered 'roger' then observed that our descent was continuing below FL220. I stated to the pilot flying that our assigned altitude was FL220. He immediately returned our aircraft to FL220. At about that time the controller asked what our altitude was to which I responded 'FL220.' no further discussion of the occurrence followed, and the flight was concluded normally. In retrospect, I feel that we had received more information than was necessary which proved to be a distraction from proper monitoring of flight progress. A statement such as, 'you have traffic passing at 10 O'clock and 4 miles' should be sufficient without referring to another aircraft's assigned altitude, or expected clrncs. Such additions are distracting and have the potential of being misconstrued as a clearance. If necessary, such additional information should be prefaced with the clearance limit such as, 'maintain FL220 and expect...' rather than, 'when clear, you can expect to ...'. I have previously noticed that ATC frequency changes and/or ATC initiated radio contacts frequently occur within 1000' of reaching an altitude or immediately prior to a navigation turn point. Contacts at such times tend to interrupt the callouts normally made by the pilot not flying and to be a distraction to the pilot flying. When possible, such contacts/frequency changes would be more efficiently received after an aircraft levels or completes its turn on course, rather than just prior to the desired maneuver. Such a policy would in effect be a 'ground' version of the sterile cockpit procedures which attempt to limit distrs during critical phases of flight. Case in point: climbing out of lax wbound over seal beach a sector frequency change is given at that navigation turn point. Perhaps ATC sectors shouldn't be 'conveniently' divided at a VORTAC, etc, which appears to be the current practice. Supplemental information from acn 129869: the altitude reminder on this confign of aircraft is on the forward instrument panel, to the right of the landing gear handle. For the pilot in the left seat to manipulate the instrument on each and every change in descent clearance requires that he loosen his restraint harness, stretch across the center console and make the required change in the instrument.

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Original NASA ASRS Text

Title: ALT DEVIATION. OVERSHOOT ON DESCENT.

Narrative: OUR ATC CTLR ADVISED US OF OPPOSITE DIRECTION TFC CLIMBING TO FL210 AT OUR 10 O'CLOCK POSITION AT 4 MI AS WE WERE DESCENDING THROUGH FL230 FOR FL220. I OBSERVED THE OTHER ACFT PASS ON OUR LEFT FROM OUR 9 O'CLOCK TO OUR 8 O'CLOCK POSITION AND REPORTED TO THE CTLR THAT WE HAD VISUAL CONTACT WITH THE ACFT PASSING ON OUR LEFT. THE CTLR THEN STATED THAT THE OTHER ACFT WAS CLIMBING TO FL210 AND THAT WHEN CLEAR YOU WILL BE CLRED FOR THE CIVET PROFILE DSCNT TO LAX RWY 25. I ANSWERED 'ROGER' THEN OBSERVED THAT OUR DSCNT WAS CONTINUING BELOW FL220. I STATED TO THE PLT FLYING THAT OUR ASSIGNED ALT WAS FL220. HE IMMEDIATELY RETURNED OUR ACFT TO FL220. AT ABOUT THAT TIME THE CTLR ASKED WHAT OUR ALT WAS TO WHICH I RESPONDED 'FL220.' NO FURTHER DISCUSSION OF THE OCCURRENCE FOLLOWED, AND THE FLT WAS CONCLUDED NORMALLY. IN RETROSPECT, I FEEL THAT WE HAD RECEIVED MORE INFO THAN WAS NECESSARY WHICH PROVED TO BE A DISTR FROM PROPER MONITORING OF FLT PROGRESS. A STATEMENT SUCH AS, 'YOU HAVE TFC PASSING AT 10 O'CLOCK AND 4 MILES' SHOULD BE SUFFICIENT WITHOUT REFERRING TO ANOTHER ACFT'S ASSIGNED ALT, OR EXPECTED CLRNCS. SUCH ADDITIONS ARE DISTRACTING AND HAVE THE POTENTIAL OF BEING MISCONSTRUED AS A CLRNC. IF NECESSARY, SUCH ADDITIONAL INFO SHOULD BE PREFACED WITH THE CLRNC LIMIT SUCH AS, 'MAINTAIN FL220 AND EXPECT...' RATHER THAN, 'WHEN CLEAR, YOU CAN EXPECT TO ...'. I HAVE PREVIOUSLY NOTICED THAT ATC FREQ CHANGES AND/OR ATC INITIATED RADIO CONTACTS FREQUENTLY OCCUR WITHIN 1000' OF REACHING AN ALT OR IMMEDIATELY PRIOR TO A NAVIGATION TURN POINT. CONTACTS AT SUCH TIMES TEND TO INTERRUPT THE CALLOUTS NORMALLY MADE BY THE PLT NOT FLYING AND TO BE A DISTR TO THE PLT FLYING. WHEN POSSIBLE, SUCH CONTACTS/FREQ CHANGES WOULD BE MORE EFFICIENTLY RECEIVED AFTER AN ACFT LEVELS OR COMPLETES ITS TURN ON COURSE, RATHER THAN JUST PRIOR TO THE DESIRED MANEUVER. SUCH A POLICY WOULD IN EFFECT BE A 'GND' VERSION OF THE STERILE COCKPIT PROCS WHICH ATTEMPT TO LIMIT DISTRS DURING CRITICAL PHASES OF FLT. CASE IN POINT: CLIMBING OUT OF LAX WBOUND OVER SEAL BEACH A SECTOR FREQ CHANGE IS GIVEN AT THAT NAVIGATION TURN POINT. PERHAPS ATC SECTORS SHOULDN'T BE 'CONVENIENTLY' DIVIDED AT A VORTAC, ETC, WHICH APPEARS TO BE THE CURRENT PRACTICE. SUPPLEMENTAL INFORMATION FROM ACN 129869: THE ALT REMINDER ON THIS CONFIGN OF ACFT IS ON THE FORWARD INSTRUMENT PANEL, TO THE RIGHT OF THE LNDG GEAR HANDLE. FOR THE PLT IN THE LEFT SEAT TO MANIPULATE THE INSTRUMENT ON EACH AND EVERY CHANGE IN DSCNT CLRNC REQUIRES THAT HE LOOSEN HIS RESTRAINT HARNESS, STRETCH ACROSS THE CENTER CONSOLE AND MAKE THE REQUIRED CHANGE IN THE INSTRUMENT.

Data retrieved from NASA's ASRS site as of August 2007 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.