EMB ERJ 145 ER/LR
ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented
Human Factors; Procedure; Weather; Chart Or Publication
Our initial routing was the GILLL1 arrival into IAH from LFT. ATC issued a reroute for thunderstorms developing in the area from present position direct to GEARR; BAYYY; and GILLL intersections; then resume the GILLL1 arrival. As PM; I confirmed the reroute with ATC. Later on; ATC cleared us to cross BAYYY at 12;000 FT; which we complied with. ATC told us to resume the arrival as we approached GILLL. My Captain set 6;000 FT for RDFSH; I verified it; and we started down. When ATC asked us to verify level; I responded we were descending via the arrival. After discussion; my Captain and I realized they cleared us to resume the arrival but not to descend via the arrival. Immediately after ATC asked about our altitude; they did clear us down to 6;000 FT; the altitude on the arrival.Thunderstorms developing in the area led to an ATC reroute. When we got the clearance to resume the arrival; we started to descend via the arrival in addition to following the course; when our clearance had just been to resume the arrival.When resuming a descend-via arrival after a reroute and/or vectors; verify with ATC whether they want the descend- via portion of the arrival as well as track.
After completing an ATC directed weather avoidance track and complying with a clearance to descent to 12;000 FT on arrival to IAH; an EMB-145 flight crew was cleared to 'resume' the GILLL RNAV STAR which had been part of their enroute clearance prior to the deviation. The flight crew failed to note the distinction between resuming the STAR and 'descending via' it and began an unauthorized descent intended to comply with the charted restrictions.