*Please note that I am the son of a airline pilot, I'm a aspiring flight instructor about to finish my commercial pilots license, and my brother is a flight instructor. I am not an airline pilot. I do know the life-style because I have been around it for so long.

This is for a career as a non-military pilot.

So you want to be an airline pilot. From the outside it looks like a great career with MANY added benefits. However there are many things that you should consider before making this career decision. You will find it is not a light one.

Cost: 65K-120K
Normally it's 265$ an hour to fly a twin engine aircraft with an instructor, single engine costs about 185$ per hour. You can expect to have to pay for around 60 hours for a single engine aircraft and 200 for a multi-engine aircraft. To time build for whatever reason, either getting an additional rating or just doing it to be eligible for the airlines, you can see prices go from 85$-240$ per hour. Usually you will have to pay that rate for about 200 hours in the plane. An examiner charges 400$ fee + and additional fee's like the plane rental. Lodging while going through school costs money 600$ a month minimum for about a year. Food and gas for your car cost money. A type rating can cost a minimum of 20K depending on what aircraft you are trying to get type rate.
*type rating: A certification you need to fly a large or medium sized passenger airplane.    

Time: 4-5 Years to get into a small commuter airline after instructing.
All airlines require that you have a certain amount of time inside a certain plane before they will hire you. The reasoning behind this is because they can not be insured if anyone in the flight crew has less than a certain amount of time specified by the insurance company.

Before going into the airlines your an instructor pilot:
Ask most instructor pilots and they will generally say that they are unhappy being an instructor pilot. Especially if they have been doing it for more than 2 years. The reasoning behind this is because the job is stressful, it doesn't pay much, and it doesn't have any benefits like medical or 401k.

During your first commuter job, you are basically a prostitute:
You don't get paid much your first couple years. You are lucky to bring in 35K for the first couple years. Your work-schedule and conditions are very tough. You basically do what the airline wants you to do for the first couple years.

You have low seniority:
When you are an airline pilot you bid on lines. A line is a schedule that is published and since you are new you are the last the choose. That means you are forced to take bad schedules that you'd otherwise never want to take. Don't expect to have Christmas, new years, easter, thanksgiving or any other holiday off for the first couple years.

Airlines are a volatile market to work for:
Airlines come and go all the time. If you are one of the unlucky pilots to be working for a company that goes under then you will be low on the seniority list for the new airline you work for. That's if you get into a new airline cause all those other pilots that lost their old job are are looking for a job too. You also have to compete with furlough pilots.

Furlough is when you are basically told that you work for the company but you don't get paid and you don't work, but they just promise that they will hire you if you are on the top of the furlough list. They do this when the company needs to cut back, and how often are they cutting back these days. Economy is pretty rough isn't it.

When you are first hired you are on a probationary period where at any time the airline that you work for can fire you for what ever reason they choose.

No room for error in life:
Poor driving record-NO JOB
More than 3 failed check rides during training-NO JOB
Fired from an airline-NO JOB
Poor review from a previous employer- NO JOB
Ok so some of these are gim'mes but you really have to have a squeaky clean record to be hired and stay employed. Keep your nose clean with everything and you should be ok.

High Divorce Rate:
Being away from home so much causes trouble. Ask most pilots and they will say that they have had 3 marriages. You really have to have an independent woman in your life to make this career choice work.

Cancer and Diseases:
Being up at altitude, you have less ozone to protect your skin. There has been research that says that pilots are exceedingly getting cancer the longer they stick with the career. Also, some pilots get diseases from other countries, especially 3rd world countries. My dad got dengue fever that almost killed him when he had a layover in India.

Ages you quickly:
Being in the cockpit ages you quickly because of the recirculated air that dries your skin out. Jet lag from traveling ages you. Stress from emergency situations age's you. 

You become fat and unhealthy:
1/2 of your life as a pilot is spent not at home. So half of your life is spent eating either fast food, hotel food, or airline food. Not exactly the best food for you. You also don't get much time to exercise because you are so tired or just don't have the time.

Hey i guess the money and the travel is worth is right? You can avoid some or most of this by joining the armed forces and fly for them. Not a pitch just the truth.