Apex domains cannot have CNAME records.
Question and response
Question
dig aviationsolution.org. NS
Answer
aviationsolution.org. 5 NS ns-1667.awsdns-16.co.uk.
aviationsolution.org. 5 NS ns-1108.awsdns-10.org.
aviationsolution.org. 5 NS ns-1185.awsdns-20.org.
aviationsolution.org. 5 NS ns-1745.awsdns-26.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0