The previous posts about traffic patterns have assumed that you are operating at a non-towered field. This is because at a non-towered field, you are the controller along with any other pilots in the pattern. This post will deal with the pattern but leave the bulk of the details about towered communications out. Look for towered communication details in another post.
Towered operations follow the same pattern concepts with some exceptions. The biggest difference at a towered field is obviously communication. You don’t announce your position as you fly around the pattern. Instead, you make contact with the tower and they will give you directions to fly.
You will rarely fly a complete pattern at a towered field and rarely use the 45. Instead, the controller will decide where you will enter the pattern.
For example, if you are approaching Lancaster, PA (KLNS) on a heading of 090 to the airport and runway 8 is active you will likely be told to maneuver for the straight-in for runway 8. This does NOT mean that you should fly around the class D airspace and enter on a 45 for downwind runway 8. It DOES mean that you should turn to the right and line up on a long final for runway 8 (no downwind or base leg at all).
If you are coming from the opposite side of the field you will likely be asked to enter left (or right) downwind. Again, you will not fly a 45. The only way you would fly a 45 is if you happened to be coming from a direction where the 45 would be. But in this case it is not called a 45, you will just be asked to enter downwind.
Remember that the purpose of the complete pattern at a non-towered field is to help pilots control the airspace by flying in expected ways. At a towered field the controller is handling this and will give you instructions to get you to the runway relativley quickly.
As I will say again and again: if you aren’t sure, just ask.
They may also ask you to report a position. For example, they may say “Cessna 12345 report 5 mile final runway 8”. When you are on final 5 miles from the runway you would say “Lancaster Tower, Cessna 12345 5 mile final runway 8”.
From there the controller will usually clear you to land.
Note that when the controller tells you to report, he is also telling you to enter. So in the example above you are expected to maneuver to final. You are NOT expected to fly around the field and get on a downwind. The only exception would be if you are already on a downwind or base, in which case the controller will usually handle this by saying “Cessna 12345, enter left downwind runway 8, report base turn.” Notice that you have been told how to enter and then how to report.
Another common reporting point is “Cessna 12345, report 3 mile base runway 8”. There are a lot of conflicting opinions about what this actually means.
Some people believe that you should fly a base leg leading to a 3 mile final and report right before you would need to turn final. This seems like the least plausible meaning to me.
Others believe it means that you should fly a long base leg and report when you are 3 miles from turning final. This seems more likely and is what I would actually do in most situations.
Here is the real deal. The controller is not ready to clear you to land so he is telling you to report this point as a way to help him manage the traffic. When you report you are reminding the controller to deal with you. He has chosen a report that hopefully will be a good time to clear you for landing. So as long as you are somewhere in the base leg area and roughly 3 miles from the airport he will be happy. Still, I would love to see an official technical definition from the FAA for this.
The overall point of towered traffic patterns is to go where you are told and listen closely. The controller is managing the flow of traffic and you just need to help him to do his job. If you don’t understand what you need to do, just ask and the controller will be happy to help. Controllers are people like you and me, try not to get intimidated if you are new to flying.
Controllers are professionals, but they can make mistakes, so keep listening and looking for traffic. If the controller tells you to do something that looks unsafe, get clarification. If you are told to do something that you can’t do, say “unable”. It is your responsibility to accept commands given by the controller and turn them down if they aren’t going to work.