CAS RA Incident: Etihad ETD390 & Air India Express AXB817
Year: 2024
On 15 June 2024, a TCAS Resolution Advisory (RA) was issued during an en-route phase over the Muscat FIR as Etihad Airways flight ETD390 and Air India Express flight AXB817 converged head-on. Both crews followed RA instructions, safely regained separation, and continued to their destinations without incident.
Incident Overview
- ETD390 (A6‑AEJ, A321‑231) and AXB817 (VT‑AXT, B737‑800NG) were flying on opposite tracks in the Muscat FIR when ATC cleared AXB817 to descend to FL160. However, due to a readback error, AXB817 descended into ETD390’s flight level (FL310), triggering an STCA alert and TCAS RAs on both aircraft.
Crew & ATC Response
- TCAS RA maneuvering was executed correctly by both flight crews. ATC intervened, instructing AXB817 to maintain FL320 and turn 20° right; ETD390 resumed FL310. Separation was re-established without collision.
Outcome
- Both flights landed safely with no injuries or damage. Time-based separation was approximately 30 seconds, with vertical separation reduced to 700 ft.
Probable Cause & Analysis
- Miscommunication in ATC clearance readback caused undercutting of flight level by AXB817. Contributing factors: high vertical closure rate, crew variation in flight path oversight.
Next Steps
- Additional investigation underway including review of communications, flight data, and crew coordination. Final safety recommendations expected in the full report.
