Narrative:

We were given a descent to FL180 by ATC. The first officer was flying the leg. Upon nearing FL180; our altimeters' settings flashed; indicating a need to adjust to local altimeter settings while passing through FL180. Acknowledging that we were leveling at FL180; I left my altimeter setting at 29.92. The first officer saw his altimeter setting flash; and adjusted it to the local altimeter setting of 30.14. From the captain's seat; I noticed we were descending through FL180. I asked the first officer to level off; then told him to climb back up to FL180. He was not responsive to my comments nor took any action to remedy the situation so I stated 'my controls'; disconnected the autopilot; and climbed back to FL180. I then asked him to reset his altimeter to 29.92. He did so. I called for autopilot on and then transferred controls back to him. We lost somewhere around 150 ft during the incident. Contributing factors include a procedural error; lack of understanding; and perhaps a confusing altitude to level at. More experience; more understanding of procedures; and ATC avoiding the assigning of FL180.

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Original NASA ASRS Text

Title: CRJ200 Captain reports being cleared to descend to FL180 with the First Officer flying. As the aircraft nears FL180 the altimeter settings begin to flash and the First Officer sets QNH of 30.14 resulting in a level off below FL180. The Captain tells the First Officer to climb back to FL180 then takes the controls when the First Officer does not respond.

Narrative: We were given a descent to FL180 by ATC. The First Officer was flying the leg. Upon nearing FL180; our altimeters' settings flashed; indicating a need to adjust to local altimeter settings while passing through FL180. Acknowledging that we were leveling at FL180; I left my Altimeter setting at 29.92. The First Officer saw his altimeter setting flash; and adjusted it to the local altimeter setting of 30.14. From the Captain's seat; I noticed we were descending through FL180. I asked the First Officer to level off; then told him to climb back up to FL180. He was not responsive to my comments nor took any action to remedy the situation so I stated 'my controls'; disconnected the autopilot; and climbed back to FL180. I then asked him to reset his altimeter to 29.92. He did so. I called for autopilot on and then transferred controls back to him. We lost somewhere around 150 FT during the incident. Contributing factors include a procedural error; lack of understanding; and perhaps a confusing altitude to level at. More experience; more understanding of procedures; and ATC avoiding the assigning of FL180.

Data retrieved from NASA's ASRS site as of July 2013 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.