How soon can newborn fly on a plane?

How soon can newborn fly on a plane? I need to take a flight that will take around 4hours. Is this healthy for my baby or should I wait till a certain age and plan on taking trains till then? Will a plane damage my baby?

Dear sucker,
What Special Rules Apply to Infants and Children?
If you're traveling with an infant or small child, you should know that proper use of a child restraint device (CRD) enhances child safety on aircraft. For this reason, Southwest Airlines and the Federal Aviation Administration (FAA) strongly recommend that infants and small children who weigh under 40 pounds be secured in an appropriate CRD when traveling by air.
Traveling with the infant on your lap:
One child over 14 days and under two (2) years of age, not occupying a seat, may be carried free with a Customer paying the applicable adult fare.
Although a boarding pass is not required, you will need a Boarding Verification Document.
Online checkin is not available.
Traveling with the infant in an FAA approved car seat:
Affordable Infant Fares are available that enable a Customer to reserve a seat for an infant and use his/her FAA approved car seat.
A boarding pass is required.
Online checkin is available if the infant is traveling on an Infant Fare and is age verified.
A birth certificate is required to validate age of all infants under age two.
A medical release for travel is required for any infant under 14 days old.
Accompanied children ages two through 11 will be charged the applicable Child's Fare for the flight (does not apply to unaccompanied children ages five through 11). Proof of age may be required.
Sue...good luck

I took my baby up in a commercial plane at 3 months. We flew for 4 hours and had to switch planes. Of course this was 10 years ago and they didn't have all the regulations they do now. I.e. she rode in my lap. As far as the kid though, everything should be fine. there is nothing that can hurt him about flying.

Medically, babies can fly at any age, even at day one. Airlines may have their own policies on how old a baby needs to be to fly.

Many people recommend giving benadryl to infants during a flight to ease the pressure in the ears. Benadryl does not equalize ear pressure. Its main effect is sedation. So while it seems to help with the ears, in reality it is just putting baby to sleep.

Again, the baby will have to learn how to equalize so if you dont give him benadryl, you might find him to be vary fussy.
http://www.tinyike.com/

I took my daughter to visit my mum in Portugal from England when she was 5 wks,