Narrative:

I was flying the first leg of the day which was a ferry flight. Everything was standard and we were issued a descent clearance from FL350 to FL240 to try to get out of some light turbulence as we started down we were issued descend via the published STAR.I started to increase our rate of descent to try and stay ahead of the VNAV because the difference in our altimeter setting was 30.41 from 29.92. As I started to increase the altimeter to 30.41 our VNAV path dropped below us; so I increased the rate of descent more and deployed the speed brake. I have never used the speed brakes in this airplane as they were a fairly new modification.I captured the vpath and the airplane was flying the descent and the indication in the aircraft flight control systems (afcs) was a magenta navigation and a magenta vpth. In order to maintain the speed that was requested on the arrival I had to leave the speed brake deployed and as the rate of descent finally started to arrest a few miles from the fix then I closed the speed brakes. This action seemed to cause the airplane to pitch down even more and as I looked at the altitude the airplane was still pitching down through 11;000 feet which was the mandatory altitude so I quickly disconnected the autopilot and started to correct for the deviation.we were still able to make the crossing at 11;000 feet. The captain and I discussed the matter after we arrived and decided that the speed brake retraction caused the automation to misjudge the rate of descent required for the vpth and that in the future changes with the deployment or retraction of the speed brakes should be made at least ten miles prior to the fix in order to assure the crossing altitude would not be a problem.

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Original NASA ASRS Text

Title: Embraer Legacy 450/500 pilot reported the auto flight altitude capture feature failed to level aircraft.

Narrative: I was flying the first leg of the day which was a ferry flight. Everything was standard and we were issued a descent clearance from FL350 to FL240 to try to get out of some light turbulence as we started down we were issued descend via the published STAR.I started to increase our rate of descent to try and stay ahead of the VNAV because the difference in our altimeter setting was 30.41 from 29.92. As I started to increase the altimeter to 30.41 our VNAV path dropped below us; so I increased the rate of descent more and deployed the speed brake. I have never used the speed brakes in this airplane as they were a fairly new modification.I captured the VPATH and the airplane was flying the descent and the indication in the Aircraft Flight Control Systems (AFCS) was a magenta NAV and a magenta VPTH. In order to maintain the speed that was requested on the arrival I had to leave the speed brake deployed and as the rate of descent finally started to arrest a few miles from the fix then I closed the speed brakes. This action seemed to cause the airplane to pitch down even more and as I looked at the altitude the airplane was still pitching down through 11;000 feet which was the mandatory altitude so I quickly disconnected the Autopilot and started to correct for the deviation.We were still able to make the crossing at 11;000 feet. The captain and I discussed the matter after we arrived and decided that the speed brake retraction caused the automation to misjudge the rate of descent required for the VPTH and that in the future changes with the deployment or retraction of the speed brakes should be made at least ten miles prior to the fix in order to assure the crossing altitude would not be a problem.

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.