Originally Posted by
flyerCO
As for most D1 seats not allowing car seats, it's due to the fact they're angled.
In the words of first-gen Deltalina, use of car seats in aircraft seats angled more than 18 degrees off centerline
is not allowed. Finger wag mandatory.
https://www.faa.gov/other_visit/avia.../InFO15011.pdf
To the OP's question, I've interpreted Delta's requirements that use of a car seat or a CARES restraint is mandatory for children under two in their own seat.