The PlainGeek speaks.
During the course of planning a flight, a pilot (private or airline) expects to use the system to insure he and any passengers will be as safe as possible. It starts long before the airplane leaves the ground. The pilot will get weather reports along his route of flight. He will calculate the weight and balance to make sure the plane is within its capabilities to carry all the baggage, passengers and fuel it will need. The pilot will plan on alternate landing zones in the event there is a problem at the destination airport. He will check the upper level winds to determine the most efficient altitude to cruise for his aircraft. If in a small plane, there can be several legs of his journey that he will plan in order to take advantage of bathroom breaks and fuel stops. The pilot will review aeronautical charts and determine the best route to fly taking several things into account like weather, restricted airspace, and warning areas. He will look into facility and equipment outages. Pilots should check the status of their destination airports as well as their alternates. After all, you don't want to plan a night landing to an airport where the lighting is down for maintenance or land on a runway where a temporary crane is set up on the final approach path. When all the research is done the pilot will file a flight plan with ATC (Air Traffic Control).
During a typical flight, a pilot will make an infinite number of calls to controllers.
At the larger airports a pilot will typically talk to three controllers before he even leaves the ground. First he'll talk to Clearance Delivery. This is controller will review the pilots flight plan and issue a clearance based on airport and traffic conditions. Sometimes this controller will amend the flight plan to account for departure procedures and other considerations. After the pilot receives his clearance, he switches frequencies and contacts the ground controller. This controller is responsible for all movement of planes vehicles and other equipment on the taxiways and terminals at the airport. He will issue clearances to direct the pilot to the active runway. Once the pilot reaches the departure runway he will talk with yet another controller who will clear him to take off. After he's airborne, the pilot will be switched to a radar controller shortly after takeoff. This controller never actually sees the physical airplane. This is the typical picture most people get when they think of controllers. Some guy in a dark room looking at a radar screen like in the movie Pushing Tin (which does a pretty good job of showing what radar controllers actually do).
There are basically two types of radar controllers, Terminal and Center. A Terminal controller is responsible for controlling aircraft within a forty or so mile ring around the airport. A Center controller is responsible for the aircraft after it leaves the airports airspace and throughout the duration of the flight at the higher altitudes. The controllers job is to safely orderly and expeditiously move traffic through the system in that order. Safety is paramount above all other concerns to a controller. Followed by maintaining order and moving aircraft as swiftly to their destinations as possible. En route, a pilot will make any number of typical requests. Some examples would be altitude changes for a less turbulent ride or flight path changes to avoid weather that has moved since their planning stages. Many times aircraft are vectored for traffic that they may be in conflict with.
I have nothing but respect for controllers and the difficult jobs they do. They manage workloads and have more responsibility than most pilots and passengers will ever know. They can be responsible for more lives in an hour than a doctor will see in an entire career. When controlling aircraft they can't let up for one second. The concentration required during the busy periods is enormous. Joe public has little idea what these controllers do on a daily basis.
We all know that private companies push safety on their employees. There are only two reasons they do so. One is to mitigate potential law suits. The other is because the government says they HAVE to. Lets face it, safety and profit don't fit into the same categories. Whenever you have to implement safety protocols it directly interferes with the bottom line. So to make an organization, who's primary job is the safety of the flying public, a profit motivated enterprise can only make the system less safe. Lets say the FAA did implement user fees to users of the system. They will probably end up charging per request and for using facilities.
Here are some ways it will immediately affect safety.
Landing fees.
If a pilot or a company is going to get charged every time they land, they will push their aircraft to the limits of endurance. When filing a flight plan, pilots have to give themselves a reserve of fuel to have on board when they arrive at their destination in case there are delays or they need to land at their alternate airport. As a pilot, I never plan legs longer than two hours to allow for bathroom breaks and to check for any updates in weather. If I get charged every time I land I'll bring a bottle to relieve myself and push my plane to the limit to keep costs down. More time in the air, working with the minimum fuel reserves, and not getting regular weather updates equals a less safe pilot. When I was learning to fly, the best practice I received was when I was practicing landings. Lets face it, flying an airplane is easy. Landing the thing without killing yourself is the tough part. How well do you think the pilots are going to be trained if they get charged every time the wheels of their plane hit the ground.
User fees.
Lets say that the government starts charging users for every request in the ATC environment. Every time someone wants to file a flight plan it will cost them money. If the weather is favorable and you stay below a certain altitude, a pilot is not required to file a flight plan at all. This means that there will be more planes flying around without being in contact with air traffic at all. This is not only a safety issue but a security issue as well. I usually file a plan when I'm flying anywhere outside my home airport. It's safer for me because controllers warn me about traffic I might not see and if I have a problem I can let them know without delay. If fees are introduced, less planes will make adjustments to their flight paths for fear of being charged. The first thing to go will be passenger comfort. You think that Delta pilot is going to request a less turbulent altitude if his company gets charged for every request? Hell no he's not! The airline will, most likely, tell him to make as few requests as possible. A thunderstorm is one of the most dangerous things for any aircraft. Not because of lightning but because of wind and potential for ice accumulation on the wings and tail. What do you think is going to happen when a pilot/airline gets charged every time they want to deviate around a storm? A lot more planes flying in and around thunderstorms will be the result.
These are just a few of the safety issues that I can think of off the top of my head with a pay your way system.