REPUBLIC OF CHINA
AIC for Taipei FIR
Civil Aviation Administration
Air Traffic Services Division
No. 340 Dunhua N.Road
Taipei, 105, Taiwan
TEL:886-2-2349-6118
FAX:886-2-2349-6122
AFS:RCTPYAYX
Email:ais@mail.caa.gov.tw
 
AIC
02/15
Effective from 01 JUN 2015
Published on 01 JUN 2015
 

CALL SIGN CONFUSION

 
  1. Introduction
    Call sign confusion is a safety threat. Within a short period of time, RTF call sign confusion can occur when different airlines operate with the same flight number, or an airline operates with near sequential or similar flight numbers (more than 50% of same digits), or an airline operates an extra or delayed service with a flight number very similar to the normal service's flight number. It may cause radio communication problems and may give rise to potential flight safety incidents.
  2. Advice to Airlines
    1. Review flight numbering system constantly, and assign different flight numbers to avoid use of similar flight numbers.
    2. Avoid multiple use of the same digit, e.g. ABC 777.
    3. When two flights departure from/arrival at same airports, and their ETA and ETD are close to each other, different flight numbers should be used.
  3. Advice to Flight Crew
    1. If not understanding clearly or in doubt about ATC instruction, the flight crew must seek confirmation from ATC.
    2. Use full call sign and correct RTF phraseology at all time. All messages must be prefixed with the airline call sign and flight number.
    3. Use headsets during times of high cockpit workload, and keep monitoring ATC transmissions and compliance with them.
    4. Ensure the beginning and end of the RTF message are not clipped.
    5. Advise ATC when an ATC transmission is blocked by another transmission or if it is suspected that another aircraft has misinterpreted an instruction.
    6. Complex or lengthy ATC clearance and instructions should be written down by the flight crew. The use of "Roger" or "Copied" is not acceptable substitutes for a full read-back. The full call sign shall be included at the end of all clearance read-backs.
  4. Advice to Controllers
    Controllers shall not only comply with Air Traffic Management Procedure to deal with call sign confusion but also beware of the following situations:
    1. Observe correct RTF discipline and use full call sign at all times.
    2. Hear back carefully and ensure that is a complete read-back.
    3. Exercise particular caution when language or communication difficulties may exist.
    4. Use headsets to ensure the RTF message and the correctness of read-back. Ensure the flight crew following the ATC instruction.
    5. When transmission is blocked, confirm clearances are copied correctly.
    6. Advise adjacent sectors if potential call sign confusion may exist.
    7. The use of "Roger" is not an acceptable substitute for a reply to flight crew. The airline call sign and flight number shall be included during the transmission.