Date: 201501
Local time of day: 0601-1200
Location: I90.TRACON, TX
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent; Initial Approach
Airspace: Class B IAH
ATC / advisory: TRACON I90
Aircraft component: Flight Environment Data
Component problem: Design
Reporter organization: Air Carrier
Reporter function: Pilot Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Distraction; Situational Awareness; Workload; Human-Machine Interface
Anomaly: ATC Issue All Types; Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew FLC Overrode Automation; Flight Crew Returned To Clearance; Flight Crew Took Evasive Action
Contributing factors: Aircraft; Procedure
Primary problem: Procedure

Narrative: While on the arrival (DRLLR4; we were assigned 26R; and then later assigned a vector for spacing; and then later assigned 26L; with different altitudes than published. Many of these changes were happening late on the arrival. I continued flying; while the Captain programmed in the change and we re-briefed the changes. The changes resulted in a lack of turn anticipation from the FMS/Autopilot turning the corner intersection (DOMNO) to downwind. As we reached the intersection; I noticed the discrepancy; and immediately overrode the automation; and then placed the autopilot in heading mode to get back to the next course leg without delay and re-engaged NAV mode after a proper intercept had been established. The arrival was resumed without further issue; and there were no comments from ATC.Had we not caught the error in time; it could have resulted in a significant overshoot of the turn which should have been started earlier. It is becoming common to have multiple changes in assignments of speed; altitude; crossing restrictions; and runways; often times this is late on the arrival when we are busy complying with the published restrictions. It appears that the FMS may have some shortcomings in handling these changes without introducing errors into the automation.I experienced a similar issue on a recent trip; but at the time thought it may have been a one-time fluke of the FMS; and we corrected in a similar manner. Since I have now seen this scenario twice; I realize it is a shortcoming of the FMS that must be corrected; double-checked and monitored; especially during turns of significance on an arrival. I have now submitted an ASAP for the previous occurrence as well. In the future; I specifically intend to watch my distance from the next fix; and if the turn has not begun prior to approximately 1.5 nm from the fix; I will be prepared to override the automation. I feel that the company may also need to address this issue with a software update on the FMS to better handle the frequent changes we encounter on the new arrivals.




Synopsis: An EMB-145 First Officer reported while flying the IAH DRLLR4 Arrival and after multiple runway changes; the aircraft did not make the turn to final so the crew overrode it to prevent an overshoot. The error may be in the FMS design after multiple changes.