Finally some answers from the FAA about safety seats. Now I for one wouldn't fly with an infant WITHOUT using their seat, but it looks like if you buy an infant a seat, you are NOT required to bring the car seat. Also, states the limitations on the placement of a safety seat.
949. AIR CARRIER OPERATIONS BULLETIN NO. 8-76-48
USE OF CHILD/INFANT RESTRAINT
SYSTEMS IN AIRCRAFT
a. Recently, the FAA and the National Highway Traffic Safety Administration (NHTSA) have agreed upon a single government performance standard that will satisfy both aviation and highway safety requirements for child/infant restraint systems. Child/infant restraint systems which have the Federal Motor Vehicle Safety Standard (FMVSS) label of the NHTSA, an FAA label, or both, are approved for use in all aircraft provided they are listed on a FACT SHEET issued by the FAA.
b. FAR 121.311 requires that during takeoff and landing of an airplane, each person on board shall occupy an approved seat or berth with a separate safety belt properly secured about him/her. However, a person who has not reached his/her second birthday may be held by an adult who is occupying a seat or berth.
c. A person under the age of two may continue to be held in an adults lap or placed in a regular passenger seat for takeoff and landing. The FAA does not require but, because of the safety benefits thereof, does encourage the use of approved child/infant seats aboard aircraft. An air traveler should check with the certificate holder providing the transportation to determine if it will accept an approved seats use and whether it will require the purchase of a ticket for an approved seats use.
d. To improve emergency evacuation capabilities, the following precautions are recommended:
(1) The certificate holders training program should cover the use of child restraint systems.
(2) The child/infant seat should be secured to a regular passenger seat at all times or, if not in use, stowed as carry-on baggage.
(3) The child/infant seat should not be located in an aisle seat or in a row of seats immediately forward of, aft of, or in the same row as an emergency exit.
(4) During an emergency evacuation the child/infant seat should remain attached to the passenger seat, and only the child should be removed from the aircraft.
(5) No other passenger may occupy the same passenger seat with a child/infant seat.
(6) Child/infant seats are not approved for use in sideward facing passenger seats.
(7) While in use, all child/infant seat straps, especially shoulder straps, should always be in place per instructions provided by the seats manufacturer whenever other passengers are required to have their safety belts fastened.
e. Principal operations inspectors are requested to bring the contents of this bulletin to the attention of their assigned certificate holders.