Originally Posted by
yeg2where
OP said the infant was held for take-off & landing, i.e. when seat belt sign is on. Do the T&C prevent AC from accepting full J fare for a seat which is not used when the seat belt sign is on and which has no associated costs to AC (no food, no drink)?
No. AC can (and does) accept full J fares for cellos. It does accept full Y or J fares for empty seats. You can book the entire executive first cabin for yourself if you want - clearly the seats would be empty whether the seat belt sign is on or off, and no food will be served in those seats.