Regional Jet 200 ER/LR (CRJ200)
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Confusion; Distraction
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Human Factors
ATC had given us a series of headings to avoid an active MOA. After the headings; they gave us direct CULAB then DIESL for the DRLLR5 arrival into IAH. I was writing the clearance while the captain put the change in the FMS. I copied the correct clearance (direct CULAB; DEISL then the DRILR5) and the captain input direct CULAB then DIESL for the MSCOT4; our originally assigned arrival. A proper cross check was not applied and the change was CONFIRMED. The MSCOT4 and DRLLR5 are very similar coming from that direction and both start at DIESL so upon looking at the first page of the FMS all seemed correct to me. It was not until later in the arrival were we/nor ATC aware we were on the wrong arrival into IAH until around the SUUNR intersection on the MSCOT4. Proper cross checking was not implemented on the arrival change. We did confirm the route change to CULAB then DIESL. A more thorough cross check of the arrival change would have caught the issue. Neither of us caught it and continued the flight to IAH on the MSCOT4; even fully briefing it. ATC said 'no worries' and left us on the MSCOT4 all the way into IAH.
First Officer reported flying the originally assigned Arrival procedure into IAH after acknowledging an ATC clearance for a different STAR.