Pilots deal with control towers all the time and most think they know what the tower is supposed to do, but … probably not. In this video, AVweb’s Paul Bertorelli explains what air traffic control towers are actually supposed to do. And it isn’t to keep airplanes from colliding in midair, but on the ground. Yes, really.


  1. Nice work Paul.

    Even though what you say is true, the controller(s) at Centennial recently may get a slap on the wrist. You didn’t mention what kind of radar was available there. Also existing rules and procedures can always be changed for the future to increase safety. (Hopefully we’ll never eliminate 91.3!)
    While the Cirrus obviously overstepped their responsibility, you could have also got into use of ADS-B with two pilots. This includes good communications procedures between the two whenever either sees traffic with the eyeballs or with ADS-B. As you know, traffic is not always easy to see. Four eyes can be better than two (sometimes!).
    The most obvious prevention fix would have been for the Cirrus to have had better speed and position control, along with the obvious separation control and more awareness of the criticalness of procedures for parallel runway operations.
    In summary, your right, in the pattern, your never going to put all the responsibility on the controller. 91.3, 91.3, 91.3…
    The Cirrus obviously F’ed up big time, but intervention by a controller in the last 10 seconds still might have prevented the accident, even though not their primary responsibility.

  2. Wow! As a 38 year ATC kinda guy (63 years pilot), I say, “Good one!” You covered it! Oh, you did leave out the part about its ok for towers to let two airplanes to use the runway at the same time under certain conditions. Hey, even as an ATC guy for my first 8 FAA ATC years, and having flown much longer, I too didn’t know VFR towers didn’t separate me in the air. I’d been a radar guy up until then. I transferred over to LGB tower in ’75, heyday of VA flight training. My first day in the tower I looked around at the patterns, airplanes up the, well you know. I told the controller I was watching, how in the hell do you keep them all separated, you must be having deals all day long. He said son, “we don’t separate airplanes in the pattern. That’s their problem. Hence, no deals”. I said, “Damn, I didn’t know that. I think I can do this.” And so it was. With LGB usual 3 miles in fog and smog, I frequently found myself saying this. “Cessna 23 Zulu, report the green tank, three miles east, for a straight in runway two five right. Four more aircraft reported inbound to the tank.” And that was my sequencing and separation for those five airplanes. Nothing more I could really do for them. Somehow, it all worked because L.A. basin pilots had the “big flick” back then as to how it all did work. I will say that sometimes when they would report the green tank in 1,2,3 order, by the time I could actually see them on final, their sequence had changed to 3,2,1. Somehow, it all worked though. Oh, during my years, a controller “deal” would first require the controller to be decertified and then spend three days in “the hall of shame” (classroom study for an new check ride recertification).

  3. Thanks for punctuating this topic. I’ve lost count of how many (good) licensed pilots I’ve instructed that have this misunderstanding. I don’t think this point is talked about much and with the usual good service we get from towers, many pilots assume separation.

  4. What Don said back up at the top, at first glance does present thoughts about more controller involvement that maybe should have been happening with this accident. But two things specifically made it very impractical or impossible for controller prevention of the accident. First, eyeballs. The accident was far out on the final. This distance, even if the controllers did just happen at that very moment (seconds involved here) look at that specific part of their busy airport, pattern, and runway activities, it is very unlikely they could have even seen the aircraft. Had they actually seen the two very distance aircraft, no way could they actually determine that they were so close to each other as about to hit. On parallel runways, aircraft always appear very close to each other and frequently converging until one of them turns inbound. Just the nature of running parallel runway patterns. The finals were only separated by 700’.
    Which also now brings the use of the radar into play. The radar, which is set on a longer range than just out to that point, the scope being (I’m guessing) 16 inches, or maybe now a more modern PC type display, the two targets will always at 700’ apart look like they are almost touching. And with parallels, this goes on all day long. If the two targets were actually still merging, as these were, the difference between assuming adequately separated and hitting is only seconds, not nearly enough time for the situation to be digested, considered, and acted upon, if, big if, the controller just happened to be looking at them at that moment . A local controller’s workload divides his/her attention constantly. When a situation (traffic issued, traffic seen) is accomplished, that situation gets back burner while local concentrates on the next in priority activity. There can be 10 lined up for departure waiting for a break in the landing traffic, so many other pending considerations. The focus is never just on one activity, especially one that is considered resolved and is as routine as the other hundreds like it that happen during the shift. It’s the way the system has been set up.

    The VFR airport world as we know it has operated like this for, well, all my 63 years of flying and other years of being a controller in such activity. There is an expectation that aviators flying in that type environment do understand what is happening and have the experience to operate accordingly. But, we, pilots do have a choice. If we do want the controllers to become responsible in insuring our separation from each other, we already do have procedures in place that do just that and work extremely well. That is what IFR does for you. The controller assumes total responsibility for separating you from other traffic including spacing you according to specific separation standards all the way to touchdown. I realize that visual separation can be applied if weather and traffic permits. If we want that, then all airports would have to become class B to insure the separation even when VFR. And for each of our flights, we would have to have an ATC clearance with appropriate instructions issued so ATC could insure our separation through positive control. VFR pattern, no, couldn’t work if you want to be positively separated. I see a touch and go being issued climb out instructions and returned to radar control for another trip around the big radar pattern. And you can let your imagination take you further into where this type of control would go, including a radar facility to serve each airport. If enough pilots feel strongly enough about our needing positive ATC control for all of our flying activities, maybe EAA/AOPA would be willing to examine the issue.
    I’m not trying to be a smart ass (although did work for FAA for many years). But many things that seem like a very good idea are just, as we collectively have the system designed, just sometimes won’t work as well as it might appear on first glance. I conclude my opinionated BS at this time.

  5. Good information–made even BETTER by Paul’s acerbic commentary and explanation–CLEVER ILLUSTRATIONS, and PUNCTUATED by humor (“Jeopardy theme”–“”Stupid Chit”–and the “Few Good Men” clip) and self-deprecating commentary.

    Move over, John and Martha–if Paul did this for an entire ground school, not only would people strain to keep up with the commentary and humor, but it would be a best seller! There are more quotable quotes in this clip than any movie EXCEPT “Blazing Saddles!”

  6. Paul:

    Great video, as usual. it is amazing how few pilots realize the separation responsibilities of a tower.

    One dispute. You implied that pilots do not have to follow instructions from a VFR tower on separation. I do not believe that is correct. See 91.123 (b): Except in an emergency, no person may operate an aircraft contrary to an ATC instruction in an area in which air traffic control is exercised. This is not just limited to ARTCCs and TRACONs.

    So, you gotta follow instructions, but it is important to understand that those instructions do not assure separation.

    Again. Great video.


    Vince Massimini
    Kentmorr Airpark MD (3W3)

    • I disagree. AIM is clear on this and I quoted it. It’s in 4-3-2

      To provide a direction or suggested heading. The local controller may provide pilots flying VFR with generalized instructions which will facilitate operations; e.g., “PROCEED SOUTHWESTBOUND, ENTER A RIGHT DOWNWIND RUNWAY THREE ZERO,” or provide a suggested heading to establish radar identification or as an advisory aid to navigation; e.g., “SUGGESTED HEADING TWO TWO ZERO, FOR RADAR IDENTIFICATION.” In both cases, the instructions are advisory aids to the pilot flying VFR and are not radar vectors.

      Pilots have complete discretion regarding acceptance of the suggested headings or directions and have sole responsibility for seeing and avoiding other aircraft.