ATCC Controllers' Read Binder...

NOTAMS, FAQs and other info for users of ATCC

March, 1998

#1: Voice Recognition Driver

The upcoming voice recognition driver for ATCC is still being refined, but will allow you to use ATCC with the IBM series of voice recognition software, "Simply Speaking" and "ViaVoice." Both of those software packages come with a headset, with Simply Speaking costing around US $50 and VoiceType around US $110. (There are also "gold" versions of each, but the extra features are not used with ATCC). The less-expensive Simply Speaking requires "discrete" speech, which means you have to speak s-l-o-w-l-y and with pauses between words, while ViaVoice lets you speak without pause. For an example of the way you have to speak to be accurately recognized, first listen to this .WAV file:

Example of normal controller speech

Now, the same command spoken for VoiceType:

A little more slowly for ViaVoice

And finally:

Even slower for Simply Speaking.

Speech recognition is a hugely complicated task requiring a great deal of processing to be passably accurate, with a Pentium 166 needed at a minimum, and the faster the CPU the better. Humans rely heavily on "fuzzy logic" to understand speech, which computers have a difficult time emulating, so even with the fastest CPU it is not as good as reality. So, do not expect it to be will likely require some practice with regular speed and clear pronounciations to be accurately recognized. Each of the IBM software packages also comes with an "enrollment" utility, in which you record about 250 pre-written sentences to train the software to your voice and accent.

Real controllers or trainees in the U.S. may have a more difficult time with the voice recognition software, because U.S. controllers are used to talking a little faster than what would be acceptable elsewhere. This is probably because the vast majority of pilots in the U.S. are native English speakers, and are more used to rapid or somewhat slurred English. Other places in the world are probably more like the ViaVoice (or even Simply Speaking) speech example, with neither the pilot or controller speaking in their native tongue, so the rate is slower.

If you do plan to get voice recognition for ATCC, you may want to start practicing aloud now (if you don't already) as you work the sectors. Each of your transmissions should be spoken as if the pilot had just said "say again, your radios are weak and garbled"--i.e. more distinct and precise to make sure they understand.

We will have more information on when the program will be ready, and where to get it, in the next newsletter. Also, if you would like to be a beta tester, email your name, address and serial number (from the back of the manual or 3.5" disk) to You will need one of the IBM speech products (ViaVoice recommended), but you shouldn't purchase it just for ATCC quite yet until you get confirmation from us, by email.

#2: Speech Mannerisms

It is significant to note that all of the ATCC pilots speak in the "casual, professional" manner of real-life airline and commuter pilots. Since most of Center controlling involves airline and commuter flights anyway, it is usually an accurate depiction. However, most real-life private pilots (the N- callsigns in small, single-engine aircraft) usually sound a little nervous on the radio, probably from lack of practice and experience. Controllers (should) adjust their speaking patterns to fit how professional the pilot "sounds," because a rapid-fire instruction to a new or low-time pilot will just be lost or misunderstood.

Pilots, too, adjust their speech depending on how the controller sounds. A nervous controller trainee may get more "when can we expect higher?" calls, or "do you still need us at 250 knots?" reminders from the grumpier pilots, and even extra-cheerful calls from others (as if implying you're doing good, hang in there!). Fast-talking controllers who sound like they know what they are doing will get fast, prompt replies, while fast-talking controllers who sound like they've lost control of everything will get somewhat hesitant and more precise readbacks, as if saying we will do what you just said, but are you SURE that is what you want?

Because ATCC can't hear your tone of voice, most of the readbacks are the type you would hear if you were a friendly, experienced controller completely in charge of the sector. If your actions, though, indicate that you don't know what is going on (like not warning aircraft about rough rides, or slowing somebody down, then speeding them up, then slowing them down again), their tone of voice may change. But in real life, the status of the sector, and your ability to handle what is happening can be conveyed just by how you speak.

Sometimes the tone of voice can be misleading, though, which is why the keywords emergency and immediate are set aside to indicate a critical situation. In the Avianca airliner crash on Long Island not too many years ago, the pilot did not use emergency or immediate, and his tone of voice remained professionally casual, leading the controllers to believe their low fuel situation was not critical.

"Emergency," or "immediate," though, should send an alarm to anybody on frequency, regardless of the tone of voice used. An example of this can be found in the ATC audio tape (and transcript) of the Valujet 592 crash. Though the pilot sounds business-like in his initial request to return to Miami, his use of the key word "immediate" indicates an urgent situation, which the controller treats as a full emergency (referring to it as such on the interphone).

Though the controller generally sounds calm and routine, the subsequent nervousness coming from the voice of the highly-trained airline pilot is certainly noted by the AAL960 pilot, who seems aware of the critical situation and replies with a quick readback so he won't tie up the frequency. Both sides, controllers and pilots, do rely on one another's tone of voice in determining what is "appropriate" for the situation.

#3: Critical Situations

The ValuJet emergency illustrates a "correct" way of handling a critical situation, whether it is a deal that just happened (or is about to happen), a full emergency, or any other distraction to the normal flow of the sector. Specifically, the controller needs to keep up with the scan, which is evident in this case when he moves up the scope to AAL960 (turning him back on course), then over to EGF703 (switching him to the next frequency)---when you see something that needs to be done, you just do it and move on. There also wasn't much the controller could do for Critter 592, except provide the headings and wait for them to turn, and in the meantime move on in the scan.

Not on the tape (but certainly happening in the background) would be the supervisor notifying and coordinating with the appropriate facilities, and possibly other controllers jumping in to help with coordination, or offering suggestions. Then there can be some confusion, for example if the supervisor is not plugged in, but says to "bring him into runway 12, they're ready" just as the pilot is stating they need the "closest available airport" instead. With many people talking at once, and amid the possible confusion, it is easy to overlook other situations in the sector. Thus controllers are trained to always keep up with the scan, even in unique emergencies.

Also, the voice tapes are always recording, and any such emergency or deal will be scrutinized by many people, so it is important to go by the book as much as possible. Even if the emergency or accident were unavoidable, an entirely unrelated mistake, omission, or non-standard procedure will be amplified and considered an opportunity for blame. Yet the controller also needs to adapt, and improvise with little time to think, so there is no easy solution, as usual. The controller in the ValuJet crash did the best that could be done in such an emergency situation, which of course don't always have positive outcomes.

#4: Coordination With Other Sectors

In ATCC, the only need for the interphone is when relaying an instruction to an aircraft not yet on your frequency, or to ask that it be switched to your frequency. In the real world, these are also common reasons to coordinate with another sector:

  • If something about an aircraft changes after you have made a handoff. This is because the next sector took the handoff based on the altitude in the datablock, or the route of flight listed on the strip, or the assumption the aircraft is at its "normal" speed. If you then change one of these things, you need to notify the next sector about the changes, and that sector has the right to "refuse" the change or the handoff, though in practice they will provide an alternate instruction that hopefully works for both sectors.

  • To seek permission to enter or cross through another sector without making a regular handoff. This is called a "point out," and is used when the aircraft is just going to clip the corner of another sector, or is otherwise not going to be in that sector very long. It saves the hassle of switching the aircraft over, only to have it quickly switched over to another sector again. The controller puts up the datablock on the other sector's scope (with a command equivalent to <F7>sector# CID), then calls the sector and says "Point out", the position of the aircraft, callsign, and what that aircraft will do, such as "will be descending to 240," or "just coming up to your boundary, then turning north", or just "eastbound." If that is OK with the other controller, he says "point out approved," otherwise can provide alternate instructions (like "just down to FL260 is approved", or "reference VIR007, point-out approved.") In ATCC, you can't make an official point-out, so try not to stray into another sector. If you need to, though, consider it automatically approved.

  • If an aircraft that was pointed out to another sector will now do something different. This, of course, is because the original point-out was approved under the original conditions, so changing them will require new approval.
  • To pass along information not on the computer flight strip, like a heading assignment or speed, and the reason for issuing it. For example, "UAL150 assigned mach .72, at Flow Control's request." (In ATCC, speed or heading assignments are passed automatically.)

There are various other reasons for coordinating with other sectors (such as finding out ride information), but the above reasons are the most common. When you are busy, it is very inconvenient and distracting to have to go off frequency and wait for the other controller to finish what he's doing and say "go ahead," so the D-side (or even a third "handoff" controller) takes over most coordination. They just have to be sure to properly inform the R-side on what they just coordinated, though, so that there are no misunderstandings. Some of it can be done silently, by marking the strip (such as a red circle indicating the information was forwarded to the next sector, or an altitude written and circled in red to indicate the next sector wants them at that altitude). If the controller is extremely busy and can't look at the strips (or just doesn't care much for strips), the D-side has to somehow get the R-side to hear and understand the information, whether it is waiting for a break in the radio chatter to slip in that "sector 34 wants DAL833 at FL330," or loudly tapping on the strip until the R-side looks over and sees the information. Whatever the case, the D-side ultimately bears responsibility for making sure the R-side learns about the coordination. The R-side, though, also has a responsibility to be at least semi-aware of what the D-side is doing, using the other ear or eye not on the scope... it is supposed to be a team effort, especially when things are busy.

#5: Featured Sector: ZLA19

It is possible to treat sector 19 as an "easy" sector, akin to the relative simplicity of sector 82, and you can be certified and work it the "easy way" without problems. It really has few traffic conflicts, and SoCal approach (77) will always take the handoffs.

However, to be true to the simulation, you must follow the spacing requirement to LAX (10 miles in trail), which is what makes it difficult. SoCal controllers working the LAX arrivals (sector 77, "Downe" sector) are in reality usually grumpy and unforgiving, probably because they quickly tire of the endless streams of traffic, day after day, trying to cram into just two parallel runways with hardly any room to vector aircraft around.

In Southern California, it has evolved that LAX airport and the LAX approach sectors run the show. If they say they need 10 miles in trail, the Center (i.e. 19) must give them 10 miles in-trail. Not 8, not 9 "and increasing", but 10. They will not take a stack of two aircraft at 140 and 150, because you were "too busy" or missed a turn. If you attempted a handoff like that, they would get on the interphone and tell you they weren't taking the second handoff, then hang up on you. You then have to spin the second aircraft around and find another slot to put him in, but there probably won't be any, so you will need to turn 5 others out of the way to fit him back in. Then ZLA Flow Control (who always watch sector 19) will call and demand to know what you are doing, because turning out those 5 will mean everybody else in line behind them (in other sectors) will have to be turned out also. You might then ask them why they've allowed so many aircraft to be released to LAX when LAX is obviously backed up, and they will get defensive and start an argument on the interphone as you go down the tubes. Then other controllers next to you will start taunting you that you can't do your job ("good-natured," but still annoying) can be a very unforgiving sector!

So, do not handoff LAX arrivals, even though 77 will take them, unless you have 10 or more miles of spacing between them! If the aircraft gets to CIVET, and you see less than 10 miles, you should turn them back to the east (maybe a 70 heading), and fit them into the next available slot. You may be able to get away with only 9 miles at CIVET, or 8 if you are quick, if you turn them maybe to a 270 heading, then as soon as you see the target move up, give them ..LAX again. But if it is not 10 miles by the boundary with 77, you will have to turn them back.

How to get exactly 10 miles of spacing is not easy to describe, and mostly comes with practice, which is why the manual lists it as one of the "harder" sectors. The range rings are the important tool in the sector, but with different head winds and ground speeds, you may find that aircraft exactly 10 miles apart at the east end of the sector degenerate into only 7 by CIVET. This is where some experience with speed control helps: "matching" speeds may mean 270 knots to one aircraft, and 280 to another, depending on headwinds. Also use +10K or -10K to fine-tune speed differences, if you try to match speeds initially, but see that it isn't working.

As aircraft get closer to CIVET, you may need a last-minute drastic turn to get them in line, but that can quickly snowball and affect everything else. Ideally, you should have the spacing by the time they cross the sector 01 boundary line, and from there to the boundary with 77 should be fine-tuning the speeds, at most. If the headwinds make matching speeds difficult, aim for 12 miles of spacing initially, which leaves you some room if you have problems matching speeds later.

Once aircraft face the same direction after CIVET, they will have the same headwind, so should then be assigned the same speed. This may mean that the HEC..CIVET aircraft at 290 knots to match the TNP..CIVET aircraft at 280 knots, would need to be slowed to 280 after passing CIVET, if you have a bare 10 miles. If you plan for a little extra spacing, maybe 11 or 12 miles, then it is OK if their speeds are a little off--you won't lose it by the boundary.

But, if you consistently work to achieve the spacing and end up with more than 10 by the boundary, you are wasting space and may get as much taunting from fellow controllers as if you had less than 10. Though, it is better to always get 15 than to always get 9.

There are occasional "good guys" at sector 77 who let you get away with 9, or even 8 miles spacing, just occasionally, if you talk nicely to them and explain your situation. If you see no other way, and only do it maybe once per hour, go ahead and slip one in with only 8 or 9 miles spacing. There is somewhat of an "honor" system with ATCC sector 19, but to be fully realistic you should settle for no less than 10.

That 10-mile spacing requirement simulates LAX's spacing declaration, which actually varies day-to-day, depending on weather. Most commonly, though, they declare it to be 10 miles-in-trail, so that is what the ATCC sector 19 must give.

The spacing requirement is so critical (and probably too burdensome for a lonely sector 19 controller), that the real-life 19 is more straight-forward than ATCC 19. They break apart the CIVET area into its own "mini" sector, number 20, that just watches the final line-up after CIVET and deals with the grumpy approach controllers. Also, Flow Control watches just the LAX arrivals on a separate scope that sees them out to about 300 miles away, or even nationwide on a smaller computer screen. They coordinate with high-altitude controllers to try to initiate some spacing prior to reaching sector 19, so 19 doesn't get stacks of aircraft on top of each other.

In ATCC there is a "flow" control to ensure that there will always be a slot "somewhere" for the LAX arrivals, though you may get an occasional stack. If you do get a cluster going to LAX, like 3 within the same 10 miles (or even 3 in a dead tie), most likely there will be extra room behind them to fit in all 3, without having to spin an aircraft in circles.

As a last resort, you can also do what they do in real life when 19 just completely goes down the tubes: take out whichever aircraft are tied or don't have a slot, and re-route them ..PMD..LAX, at FL220 (or below). This is called the "back-door" routing, which pilots hate, but is sometimes the easiest solution for everybody else. You would normally hand them off to sector 18, but the ATCC 18 won't take the handoff, so just let them fly off the screen. If you have a D-side, he will handle the coordination, and if (or when) the aircraft asks for lower, give him 140, then when he asks again later, switch him to 124.9.

The spacing requirements and everything you need to go through to get it at ZLA19 also applies to every other sequencing/approach sector everywhere else, so a mastery of 19 will make "lesser" sequencing sectors like 75 and 66 seem easy. In fact, if you can master ATCC sector 19, you are likely better than the 90 percent of the real-life center controllers who don't work major sequencing sectors, and never get to learn the noble art of sequencing...


The Read Binder is updated at the beginning of the month. All information is for use with Xavius Software's Air Traffic Control CenterTM only, is the opinion of the author(s), and does not necessarily reflect the policies or practices of the U.S. Federal Aviation Administration or Federal Aviation Service. Send your questions or comments to and we'll be glad to help!