Narrative:

The problem happened during the start of the SHFTY1 arrival after our descending to FL400 for direction of flight cruise segment into florida. The flight was being flown under single-pilot rules; with the copilot watching for traffic and gaining operating experience and familiarization with the new aircraft make/model prior to formal simulator-based training in a couple of months. As the copilot has several years operating experience with the same avionics suite in the flight department's prior aircraft; he was working with the FMS reviewing the planned arrival procedure and approach. With the autopilot on; we were briefing the arrival and approach; and I was explaining the use of VNAV; when we received a call from ATC to descend to FL390. I acknowledged the call; acquired the climbing airliner in the distance; with the airliner crew looking for and acquiring us from the directions given by ATC. The airliner was about 15 miles away; closing; moving from our 10 o'clock to 3 o'clock position. I was maintaining visual contact with the traffic when I heard the altitude alert chime signal; realized the aircraft was not leveling-off; immediately disengaged the autopilot stopping the descent at FL385; and initiated a climb to rejoin FL390. During my scan of the pfd and fgp (flight guidance panel) during the climb I saw the indicator flags noting the autopilot had joined the VNAV descent profile from the FMS to FL380; which we programmed but had not executed (expected altitude) just moments before the ATC call. My mistake was continuing the familiarization and instruction during a high-workload period that had abnormal circumstances; due to a pending space shuttle launch. While we were briefed on the launch notams; and discussed their impact on our flight; we too quickly diminished its impact as it was hours away; with our course on the opposite (west) coast. The controller was at his maximum workload; with the frequency congested; as he was trying to sequence traffic in the reduced airspace. I should have realized our briefed plan and how I was operating the flight had changed the moment the frequency and airspace was constrained. My allowing the copilot to assist with the FMS and fgp commands; while I was looking and communicating about the traffic; was wrong. I omitted crosschecking my copilot; and was fixated on the traffic and communication with ATC. I had set myself for a problem by having a mind-set to use the FMS to its fullest (advanced techniques and operations) as when flying single-pilot; just as I had been doing following the emphasis in my recent training course just weeks prior. I assumed the copilot had the correct fgp programming sequence based on our discussion and drill several minutes earlier; and failed to realize his lack of knowledge and currency with the avionics system. I should have used basic autopilot and raw data commands; with me commanding the autopilot; and the copilot looking for the traffic. We did not have a TCAS TA/RA; and at the closest were about 5 miles and 2000 ft from the crossing traffic. The altitude query by ATC to our passing FL390 only added confusion to the congestion that the controller and fellow fliers were experiencing. It seemed as though it took twice as long to clarify and explain our correction that it did to actually do it. Luckily only professional pride was damaged; and a lesson was learned. Our flight department has had a traditional 'sterile cockpit policy below 10000 feet' policy; but following this we have revised that to include any part of the climb; descent; or abnormal- cruise phases of flight. As an instructor; I learned that advanced avionics techniques are better explained and practiced on the ground and in the simulator where time and motion can be paused when we become task saturated.

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Original NASA ASRS Text

Title: RA390 Captain reports descending below assigned altitude after not checking FMC inputs by not flying pilot. Reporter was acting as single pilot and instructor training the other pilot.

Narrative: The problem happened during the start of the SHFTY1 arrival after our descending to FL400 for direction of flight cruise segment into Florida. The flight was being flown under single-pilot rules; with the Copilot watching for traffic and gaining operating experience and familiarization with the new aircraft make/model prior to formal simulator-based training in a couple of months. As the Copilot has several years operating experience with the same avionics suite in the flight department's prior aircraft; he was working with the FMS reviewing the planned arrival procedure and approach. With the autopilot on; we were briefing the arrival and approach; and I was explaining the use of VNAV; when we received a call from ATC to descend to FL390. I acknowledged the call; acquired the climbing airliner in the distance; with the airliner crew looking for and acquiring us from the directions given by ATC. The airliner was about 15 miles away; closing; moving from our 10 o'clock to 3 o'clock position. I was maintaining visual contact with the traffic when I heard the altitude alert chime signal; realized the aircraft was not leveling-off; immediately disengaged the autopilot stopping the descent at FL385; and initiated a climb to rejoin FL390. During my scan of the PFD and FGP (flight guidance panel) during the climb I saw the indicator flags noting the autopilot had joined the VNAV descent profile from the FMS to FL380; which we programmed but had not executed (expected altitude) just moments before the ATC call. My mistake was continuing the familiarization and instruction during a high-workload period that had abnormal circumstances; due to a pending Space Shuttle launch. While we were briefed on the launch NOTAMs; and discussed their impact on our flight; we too quickly diminished its impact as it was hours away; with our course on the opposite (west) coast. The controller was at his maximum workload; with the frequency congested; as he was trying to sequence traffic in the reduced airspace. I should have realized our briefed plan and how I was operating the flight had changed the moment the frequency and airspace was constrained. My allowing the copilot to assist with the FMS and FGP commands; while I was looking and communicating about the traffic; was wrong. I omitted crosschecking my copilot; and was fixated on the traffic and communication with ATC. I had set myself for a problem by having a mind-set to use the FMS to its fullest (advanced techniques and operations) as when flying single-pilot; just as I had been doing following the emphasis in my recent training course just weeks prior. I assumed the copilot had the correct FGP programming sequence based on our discussion and drill several minutes earlier; and failed to realize his lack of knowledge and currency with the avionics system. I should have used basic autopilot and raw data commands; with me commanding the autopilot; and the copilot looking for the traffic. We did not have a TCAS TA/RA; and at the closest were about 5 miles and 2000 FT from the crossing traffic. The altitude query by ATC to our passing FL390 only added confusion to the congestion that the Controller and fellow fliers were experiencing. It seemed as though it took twice as long to clarify and explain our correction that it did to actually do it. Luckily only professional pride was damaged; and a lesson was learned. Our flight department has had a traditional 'sterile cockpit policy below 10000 feet' policy; but following this we have revised that to include any part of the climb; descent; or abnormal- cruise phases of flight. As an instructor; I learned that advanced avionics techniques are better explained and practiced on the ground and in the simulator where time and motion can be paused when we become task saturated.

Data retrieved from NASA's ASRS site as of April 2012 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.