ATCC Controllers' Read Binder...

NOTAMS, FAQs and other info for users of ATCC

August, 1998

#1: New Sector Update

Nothing new to report, as development continues... we are also doing some other (non-ATC) projects, otherwise we'd finish it more quickly! They will be released when ready, still in "Fall '98."

If we were going to be absolutely realistic, we would release them around 10 years from now, to accurately simulate the majority of Center controllers who do the same six sectors for 10 or more years, sometimes 20. Certainly a controller who has worked a sector for 10 years in a row can do it almost by reflex, and has seen just about every situation and has several solutions to every problem already in his "bag of tricks." Getting to that stage probably makes the job less interesting, but does ease the stress when you've seen and done it all before.

#2: A Radical Concept

There are loftier issues in the world, but something that can start a shouting match on the control room floor (especially if you are being trained at a sector and dare to suggest an opinion), is to suggest that you don't care who or what they are, or where they are going. There are quite a few controllers--probably most--who firmly believe, and teach to their trainees, that you must always know the callsigns of all aircraft in your sector, and must be able to recite the aircraft types and route of flight without looking at the strip. An instructor from this school of thought sometimes will cover his hand over a datablock, and ask you to name the aircraft, current and assigned altitude, type and route of flight, without looking at the strip.

To be able to do this, in your systematic scan when you get to each aircraft, you have to remind yourself of all that information, as well as checking for normal conflicts. This leads to a greater "picture" of the sector, and probably the ability to identify conflicts further in advance.

However, you can become overwhelmed more quickly, as you have to retain more information in each scan. This leads to the outrageous concept in Center controlling of not bothering with the type, route of flight, or even callsign in your scan. When you get to each aircraft, you just look at where they are and where they are going right now by the histories behind the target, then glance up at the altitudes to confirm they are separated from nearby traffic. You figure out where they need to go based on where they are in the sector, for sectors that are highly proceduralized, or based on where you put the datablock when you first took the handoff (like ORD arrivals "up", overflights "down," for example).

Controllers who work this way often have a greater delay in finding aircraft when they first check on, because callsigns aren't part of the scan. They are also a little more prone to forgetting to descend an arrival, thinking they are an overflight, for example, or possibly running into last-minute conflicts if an aircraft is on an "unusual" route that they forgot to note. But, they can work a lot more traffic without going "down the tubes."

Ultimately, which of the two techniques to use (or combine) depends on the sector. You may be better off knowing everything about aircraft in some sectors like L.A. 4, where you need to know which departure to get above the other by their final requested altitude or ultimate destination, for instance, whereas in other sectors like 75 you really don't need to concern yourself with anything until they start merging around DBQ, then you can start spacing only the ones that turn left (for ORD) all without looking at the strips or caring much about aircraft types (and thus speeds and performance). You might check the strip only if you see a conflict, or if you notice an overtake and want to decide whether to change their altitudes or assign speeds.

The "old school" controllers condemn the idea of not memorizing all the information, possibly as a holdover from the earlier days when radar and computer "burps" weren't just one-update blinks, but 10 minute outages. If you didn't have everything in your head, you had to scramble a lot more to reconstruct it from the strips. But there aren't 10 minute outages any longer (with very rare exception), so you may in fact be better off with the quick versus thorough scan, in many cases.

#3: Controller Nightmares

Probably few controllers' nightmares involve losing control of the sector and having aircraft crash into each other. Because positive separation is so highly ingrained, where you only take handoffs or issue altitudes when you know for certain that the altitude is safe, at any given time you know that all of your aircraft are separated. Even if/when you lose the flick, you're not so much worried about conflicts as you are about identifying which aircraft need to be spaced apart and descended for arrival.

The great anxiety comes from missing a handoff. Seeing aircraft blink in conflict should certainly cause a lump in your throat, but so should seeing one of your aircraft on the other side of your sector boundary without a handoff. That is an easier error to make, and is also grounds for decertification. The only way to really prevent it is to have a constant scan. However, sometimes you just can't help fixating on a knot of traffic, or for some reason you might think you see the "R" in the datablock indicating a handoff is made, when it isn't, or /0'ing the datablock thinking you have already handed off and switched him when you haven't. Then the next sector calls up and demands to know what the aircraft is doing in his sector, or worse yet doesn't notice the backslash until the computer starts blinking in conflict. Your deal!

The solution: scan scan scan scan scan!

#4: Military / Special Flight Procedures

Military flights were left out of ATCC mostly because ATCC uses actual routings and traffic levels from the real sectors, and because of our access to that data, showing military flights (even if randomized) might somehow indicate the actual levels of military activity in the U.S., which would require review and approval from the Government. Knowing that could take awhile, or take forever, military flights were just left out.

Military flights are really insignificant, in most cases, because they are just overflights like any other. An F-15 might be traveling across the state to another base, or a flight of two C-141's might cross the sector on a training mission. Functionally it is no different than a civilian lear jet, for example, and military flights are still required to follow the same procedures as everyone else.

There are some situations that can present a challenge, however. There are various practice missions, especially in coastal sectors, where a couple dozen aircraft might launch from an aircraft carrier on a training flight, crossing through the sector (though usualy in a neat line). Such missions are coordinated beforehand, so the controller usually knows it is coming, and just blocks off the altitudes from other aircraft until they all pass.

There are also pre-set military training routes, called IR and VR routes, that appear on aviation charts for everyone to know about and use extra caution when crossing. Most of these routes are very low (maybe 200 feet in unpopulated areas up to 7,000). VR routes are for VFR flight, where the military aircraft just flies it on its own without coordination with ATC. IR routes are for IFR, where the controller approves entry into the route, and gets a time estimate for when the aircraft will pop out the other end. All sectors in-between are given a time estimate and altitude block to separate from using non-radar procedures. A lot of IR and VR routes criss-cross, but the military is responsible for separating different flights within those routes.

Some military / special flight terms and procedures:


This is a term that means "Military Assumes Responsibility for SeparAtion." If a military aircraft wants to join in formation with another in your sector, you first vector them and/or assign an altitude next to their target at the minimum separation amount (5 miles/1000 feet). Once they get each other in sight, they will say they are "MARSA", which means they are taking over separation and will join up. So, for instance, you may have TOPGUN1 at FL230, and TOPGUN2 you would assign FL220. When TOPGUN2 gets #1 in sight, he would say "TOPGUN2 is MARSA with TOPGUN1", then you would say "TOPGUN1 flight, maintain FL230." They join up, and you treat them as one aircraft (the second turns off his transponder).

Similarly, if a flight wishes to break up, you would assign different altitudes to each aircraft in the flight, tell them to report when established, then say "MARSA terminated" which means you are taking over separation responsibility. So for a flight of 3 at FL230, you might assign TOPGUN1 FL210, TOPGUN2 FL220, and TOPGUN3 FL230, then when they report established at those separate altitudes, you would terminate MARSA and treat them as three separate aircraft with their own datablocks, instead of one flight with one datablock.

It becomes a headache if you are busy and a flight suddenly announces they want to break up, so it is possible to deny the breakup until you are less busy, or tell them to make the request on the next sector. If they are headed into clouds, however, you may have no choice, or you may tell them to circle awhile until you can get to them.

Intercept Missions

The U.S. military has their own network of radars looking over the U.S. borders, and out over the ocean (NORAD). They are tied into the FAA computer to be able to get information on incoming flights from overseas, but if they see a target over international waters headed toward the U.S., without flight plan information, they will call on the "shout" line to the appropriate Center sector for an ID. Sector 66 might get a call to ID a radar target, and if 66 has no datablock or other information on it, the military will usually scramble an intercept flight. Essentially always they turn out to be private pilots ("VFR") not talking to anybody, who stray too far outside the boundary, then get picked up on their way back in. But, procedures are procedures, and they will likely find two F-18's on their tail within 10 or so minutes.

For the controller, the scrambles are treated like most other flights, with normal handoffs and altitude assignments, though they are given direct routes to the target. Center controllers handle the intercept, except in unusual situations, after being shown the target (or general area) by the NORAD controller. The Center controller just gives them a heading toward the area, and usually whatever altitude the intercept flight requests. When the flight leader acquires the target on radar or visually, they just take over the remainder of the intercept, and call you back when they're done and need a clearance back to their base.

"Done" doesn't mean they shoot them down, but rather they have identified the aircraft as a frightened private pilot, or possible drug smuggler, and NORAD has decided to let the Coast Guard take over the tracking and/or following. Or, they just record the tail number and send a letter to the plane owner telling them to be careful!

SUSPECT Transponders

Until the advent of GPS technology at least, the FBI or Customs could clamp on a hidden "SUSPECT" transponder to an aircraft they wished to track (drug smuggling, for example), then when that aircraft took to the skies, a "shadow" target would appear on the controller's radar with a blinking SUSP above the altitude in the limited datablock. If a controller saw a SUSP target, he was supposed to tell his supervisor who would forward the information to the appropriate law enforcement facility, which might ask to be notified if the aircraft calls up for advisories (and gives away their destination), or any other information.

SUSP targets are extremely rare now, though, probably because law enforcement uses different (GPS) tracking of their own. Controllers just need to know if they see a SUSP target, and that aircraft calls for a clearance or traffic advisories, not to ask them why they might have "SUSP" blinking next to them, as a few controllers have mistakenly done in the past.


Similarly obsolete (at least in the U.S.), but technically still in existance, is transponder code 7500. If a pilot dials in this transponder code, "HIJK" will blink in the datablock, alternating with the speed (and handoff) information.

The idea is that the pilot could secretly dial in this code probably without the hijackers' knowledge, so the controller would know of the problem. The proper procedure if a controller sees "HIJK" is to ask the pilot to "verify squawking 7500" (Do not ask "are you being hijacked??!!"), then if the pilot answers "affirmative" or doesn't answer, to assume a hijack and notify the supervisor (and try to treat the aircraft as usual, though of course let them fly where they want).

If somebody is crazy enough to try to hijack an aircraft without anybody on the ground finding out (especially since they probably could have just bought a ticket to their desired destination, anyway), they are probably crazy enough not to know about this procedure, so it is not "secret," but is pretty obsolete in today's age of air safety.

Air Force One

"A1" is the callsign of any Air Force aircraft occupied by the President, of course (or VV1 for Navy One; VM1 for Marine One, etc). Though prior to reaching their destination, the airport will shut down, while they are in-air there isn't really any special handling. A supervisor, however, is required to monitor every sector A1 travels through. Also, the controller is supposed to call traffic with any "merging targets" with A1, regardless of altitude, not just those at the minimum separation. And, of course, if they want any special routings or accommodations, you should comply, unless it takes them into traffic. It's probably common sense to move the other aircraft out of the way, though.

Communist Aircraft

The (death?) of communism notwithstanding, the U.S. State Department still maintains a list of "restricted" communist nations whose aircraft may only fly along pre-approved routes. Controllers are not supposed to take them off their routes except in extenuating circumstances, without prior approval from the State Department--i.e. no direct routes allowed. There is no advanced notice of these aircraft coming into the sector (most are regular passenger flights), and in practice there is no indication the aircraft is from a communist nation, so controllers pretty much just guess ("Thai Air 771, say system of government?" was overheard once). Or they ignore it, but technically the restriction still exists, and NORAD is usually monitoring the flight too, so the controller may get asked about it later.

An exception are certain flights per the "Open Skies" treaty with a few countries, whose special flights are allowed to go anywhere they want (subject to normal traffic handling). An Open Skies flight may decide to overfly Area 51 at 2,000 feet, for example, so you just let them go there, though maybe call Nellis Control beforehand to tell them to quick hide the alien spacecraft.

Doomsday Flights

Certain other military flights take priority handling, such as nuclear/biological disaster response teams, or the airborne NORAD command posts and bombers always in the air somewhere. They may just request to circle a given area, at a block of altitudes, or may go back and forth between points. You can technically turn them out as traffic dictates, but of course you should probably give our National Defense priority and turn out the other guy, instead.

All-Out Global Thermonuclear War

Still in the official literature (much dating from the 1950's) are the procedures for Centers to follow after a nuclear war. Centers were all constructed in remote areas, and with fortified materials, equipment and supplies to continue operating following the complete annihilation of all civilization. First, the military (most likely) implements SCATANA procedures, the official shutdown of all airways and navigational aids, the complete flushing of all military aircraft and tankers into the air (while the missiles are still on the way), and the order that controllers get all civilian aircraft onto the ground somewhere, anywhere. Centers are also supposed to act as coordination facilities for nuclear detonation reports (from pilots), and otherwise function as needed by NORAD.

That is assuming the radars and radios are still functioning, though Centers also have special LF radio equipment for use after nuclear war, to coordinate with other facilities and with what remains of the government. In practice, of course, most controllers would probably be allowed to "go home early."

Much more practical of the obscure need-to-know-at-some-point procedures:

Ultra-Ultra-High (FL600+) Missions

Technically "positively controlled airspace" in the U.S. is only from FL180 to FL600, so an aircraft (like a U2) above FL600 could fly VFR and not be in contact with ATC. Some may do this, but most regular missions above FL600 are IFR. Separation standards above FL600 are 10 miles and 5000 feet, instead of 5 and 2000. There are so few above FL600 anymore that the odds are incredibly slim any two would get within 20 miles of each other, even, but you still have to watch out for it (it has happened). The actual altitudes they fly at are classified, so the transponder stops at 600C, even if they are above. If you really need to separate them, there are frequently-changing altitude codes you are supposed to be able to locate at some sectors, such as a codeword like "BAKE." If you ask a U2 at or above FL600 his altitude, he may respond "Bravo plus 5," so if "BAKE" was the current code word, B corresponds to 60,000, A to 70,000, and so on, so B+5 is FL650.

Conflicts are so rare, though, that sometimes the codes get mis-communicated or can't be found, so you can always tell one to maintain a letter altitude, and the other a letter plus 5, and they will be separated regardless of which they choose.

Radio Failure code

Radio Failure (code 7600 on the transponder) may be seen occasionally, usually with private aircraft with bad or old radios. Dialing in this code in the transponder causes "RDOF" to blink in the controller's datablock, which is supposed to be done by the pilot if they know they have lost their radios. If this happens, aircraft are expected to remain at their last assigned altitude until the inital approach point at their destination airport, where they are supposed to hold until their flight plan ETA, then initiate an approach (and clearance to land via light gun signals from the tower). Nobody really remembers the exact procedures (it is rare enough), so in practice really you would just clear out the altitudes below the NORDO (no radio) aircraft and maybe expect them to start descending a normal distance from the airport. Aircraft with bad radios are usually the older types of smaller aircraft, which usually fly VFR anyway, so if you saw one of the V's blinking RDOF you would usually just call whichever airport tower they seem to be headed to, and let them know to dust off the light gun.

Emergency Code

Dialing in code 7700 in the aircraft transponder causes EMRG to blink in the datablock or next to the VFR target. Typically this might come from a VFR aircraft that is lost, dials in a random radio frequency and gets a controller who tells him to squawk 7700. If there is a sea of V's and I's, the EMRG code will blink and stand out, to more easily locate him. That is really the only functional use, though maybe a VFR pilot with a transponder but no radio who encounters an emergency, could squawk 7700 to alert somebody they are in trouble.

Emergency Locater Transmitters (ELTs)

In the tail of most aircraft are special transmitters designed to emit a siren-like tone on frequency 121.5 (the special emergency frequency) if impacted (as in a crash). ATC facilities have receivers always tuned to to that frequency, and most military aircraft also monitor it as well. If somebody hears an ELT, the Center will coordinate the activity to locate its source. Usually they get a rough idea where it is, then ask that sector's controller to have aircraft monitor 121.5. The controller can kind of narrow the area based on pilot reports ("it's getting stronger"), then special rescue aircraft with direction-finding equipment are launched to locate it more specifically. Flight Service stations also have direction-finding equipment scattered around the country, that they can activate remotely to triangulate the source, too.

None of the these military or special situations are present in ATCC, just because they are extremely rare, but they are somewhat interesting to know, perhaps!

#5: Tips and Hints

  • Remember not to try to "learn" anything from the computer controller when you are not plugged in. The computer is awful! It is really intended just to keep things going, handoffs made and taken, etc. Positive separation (over-separation, really) is attempted, but multiple look-ahead moves aren't, so there are numerous conflicts.

  • Ratings can go down, even if you don't have a deal. You get a rating after each session (even though it is not shown), which is combined proportionally depending on your previous rating and number of hours. If you had an 90 rating based on 10 hours, then did 10 one-hour sessions with an 80 rating each session, the weighted total would give you an 85 overall. The more hours you get, the less your rating will be affected by individual sessions, so it will smooth out as your hours build. A drop in the rating doesn't mean you are getting worse, just that you were probably overrated before and it is correcting more to how you perform overall. But if all you do are easy sectors with light traffic, your rating will be lower than if you do marathon sessions at the busiest sectors.

  • Multiple commands will get a standard "we copy all that" readback, but you can check to make sure they did copy it by looking at the strip. If all of the instructions are on the strip, the aircraft received it, because the strip will always reflect what the aircraft has, in ATCC. It does take a couple seconds to appear, though, so wait that long before checking.

  • No conflicts are ok! You shouldn't always need to be doing something, as the ideal situation is where everybody has their altitudes and are just marching along. As it turns out, you usually do need to be doing something, but sometimes you get it all done and can just watch the blips move. That is a rare, and good time to lean back and stretch!

  • Remember to get rid of aircraft as soon as you can! If the handoff is taken, and you have no need for the aircraft, switch him over! If the datablock is outside your sector, take it off! "Cleaning up your scope" in this way usually reveals you are not as busy as you thought. And when things do start to get hectic, cleaning everything up is usually a good first step to reducing complexity.

  • Fixating: Everybody knows to keep scanning, but sometimes you just can't help focusing on one thing. Something to remember is that nothing is going to change for 12 seconds (one radar update), at least, so you at least have that long to quickly glance around the sector before coming back to see if your turn is working, or if you are going to squeak out of that deal. It's hard to look away from something important, but try to make it routine, and you will find you really don't miss anything, and it helps to prevent a panic catch-up afterwords!


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!