Date: 201409
Local time of day: 0601-1200
Location: LGA.Airport, NY
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class E N90
ATC / advisory: TRACON N90
Aircraft component: Altitude Hold/Capture
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Human factors: Confusion
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types
Detector: Person Flight Crew
When detected: In-flight
Result: Aircraft Equipment Problem Dissipated; Flight Crew Overcame Equipment Problem; Flight Crew Returned To Clearance
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: We were on the HAARP3 arrival into LGA when we were given a descent and holding instructions. ATC advised that they were turning LGA around; and that we were to descend and maintain 11000 ft; cleared direct VALRE and hold as published with 10 NM legs. The First Officer (FO) was the flying pilot and entered 11000 and started a descent using PATH. He also entered the hold into the FMS and we both verified the course. When we entered the hold (which was essentially a direct entry) we were level and 11;000 ft with 11;000 ft set in the altitude preselect. The FO also had the speed set in manual at 210 kts. Upon entering the hold I made the ATC report. Just after the AP started its turn (as it should have); the auto-throttles advanced to full thrust and the AC started an aggressive climb leaving the 11000 ALT and disregarding the 210 kts speed. Again; 11;000 was set in the ALT and 210 kts in manual speeds. Because the AC was departing from its programmed values; I used TCS to take control and returned the AC to 11;000 and 210 kts. (I believe I was able to keep it from exceeding 11;200 ft.) I then gave the controls back to the FO and told him to fly it manually while I changed the Vertical mode to green ALT. The FO got us established in the hold and we were able to return to AP for the remainder of the hold. After reviewing what happened the FO said he selected one of the 3 holds in the Database for VALRE. The one he had selected showed the hold BELOW FL180. His reasoning was that since we were level at 11;000 that would be appropriate. (I would have to agree.) Regardless of the hold selected from the database the AC should never have departed from the 11;000 ft selected. I believe there is a programming error with the current software load that would allow the AC to depart from an altitude without having a different altitude selected. At no time were we prompted to enter a new altitude (which the automation will usually prompt you to do if you've asked it to make a crossing without entering the new ALT in the preselect). Bottom line the AC should never decide on its own to start a climb without us authorizing it. If I had not overridden the AP as quickly as I did we could have easily climbed into other traffic in the same holding pattern (there was none there at the time but there was a few min later).




Synopsis: EMB-175 flight crew reports being issued a holding clearance at VALRE at 11;000 FT. A database hold that matches the clearance is selected in the FMC. As the aircraft crosses the holding fix at 11;000 FT and starts to turn; autothrust advances to climb power and the nose pitches up. The Captain quickly takes control and returns the aircraft to the proper altitude and flight path. Autothrust is normal for the remainder of the flight.