Large Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP)
Fatigue; Communication Breakdown; Distraction; Situational Awareness
ATC Issue All Types; Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Returned To Clearance; Flight Crew Took Evasive Action
Human Factors; Weather; Procedure
On arrival into IND we were cleared for the approach. As PM I read back 'turn right 200 degrees maintain 2000 till established cleared the ILS 23 left approach.' Just outside RACYR; ATC informed us of a low altitude alert and were told to climb back up to 3000 feet. Once there we were re-cleared for the ILS 23 left approach. No further incidents. I would say that fatigue was the primary culprit. When we read back the clearance it should have seemed an unusual alt to intercept at; as the minimum alt at RACYR is 2600 ft. Also when I received the clearance there was chatter on guard 121.5 which could have interfered with hearing our clearance correctly. Better rest; clarification of the clearance and acknowledgement by ATC of the read back.
We must have misheard and read back an incorrect altitude during an approach clearance.
Air carrier crew on vectors for the IND Runway 23L ILS descended to 2;000 feet; but climb back to 3;000 feet after ATC issued a low altitude alert. Fatigue and a misunderstood descent clearance were factors.