Citationjet (C525/C526) - CJ I / II / III / IV
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 6
Communication Breakdown; Time Pressure
ATC Issue All Types; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Procedure; Human Factors; Weather
The pilot checked on for ILS19. I descended aircraft to 3;000 FT. I thought I heard the pilot read back 3;000 FT but I misunderstood him. The low altitude alert went off when the aircraft was descending to 2100 FT. I immediately climbed him to 3;000 FT and issued a low altitude alert. The pilot said he had thought he was cleared to 2;000 FT but I had only cleared him to 3;000 FT. We listened to the tapes and had to slow them down to understand the pilot's readback. I will question all pilots when the readback is not clear and try to use 4;000 FT when possible to avoid this situation.
Read back a descent clearance to 2;000 FT set the altitude preselect to 2;000 FT at about 2;200 FT Approach tells me to climb to 3;000 FT. I started the climb; and then they tell me to level at 2;600 FT; then they give me a heading to intercept the ILS course for Runway 19 at out destination and clear me for the approach. I thought sure I read back 2;000 FT; because the preselect was set at 2;000 FT I had the TAWS displayed; but never got a warning from it.I should have questioned the altitude because 2;600 FT is the altitude over the outer marker! Next time I will double check the final approach fix altitude.
A C525 pilot flying solo was cleared to 3;000 FT but read back 2;000 FT; a TRACON low altitude alert sounded the Controller recleared the pilot to 2;600 FT.