Say Again? #21:
ATC 103 — VFR Cross Country

Although he has a certain affection for VFR traffic passing through his airspace, AVweb's Don Brown is sometimes surprised by what pilots know (or, more importantly, don't know) about the services an ARTCC can and cannot provide. Even experienced, professional pilots can learn things for when the weather is CAVU.


With Spring just around the corner I thought we should spend some time talking about VFR operations. I know it’s been a while since we’ve covered the real basic stuff in ATC so if you’d like to review what I’ve already written, you can find everything here, including ATC 101 and ATC 102.Speaking of review, let me remind you once again that I work in an Air Route Traffic Control Center (ARTCC). Atlanta Center (ZTL) to be exact. It’s very important that you remember I don’t have a window to look out of and that I’ve never uttered the words “cleared to land” on the frequency in some 20-odd years of working airplanes.

In the Center

Besides being important as a frame of reference, there are other considerations in understanding that I’m a Center controller. Here’s a good reason right out of the AIM:

Chapter 4. Air Traffic ControlSection 1. Services Available to Pilots4-1-1. Air Route Traffic Control CentersCenters are established primarily to provide air traffic service to aircraft operating on IFR flight plans within controlled airspace, and principally during the en route phase of flight.

Right off the bat, the very first thing the AIM mentions in “services” is that Centers are “primarily” for IFR flights. Our primary duty — the way a Center operates, the frame of reference Center controllers work under — is all geared towards IFR flight.

VFR in an IFR World

That doesn’t mean we don’t work VFR flights. We can and we do. Some of the crazy folks like me actually enjoy it. Regardless of whether we enjoy it or not, this is in the AIM too:

4-1-16. Radar Assistance to VFR Aircrafta. Radar equipped FAA ATC facilities provide radar assistance and navigation service (vectors) to VFR aircraft provided the aircraft can communicate with the facility, are within radar coverage, and can be radar identified.

Have I mentioned lately how much I like the AIM? I know it’s supposed to be boring and what-not, but I have to tell you, when I start to write one of these articles, I wind up going off on all sorts of tangents in the AIM. Maybe that’s the way you should approach it too. If you just pick it up to read it, you’ll shortly be bored out of your mind. But if you’ll read it with a specific purpose — to answer a question — you’ll be surprised how interesting it is.For example, in reading 4-1-6 (above) you find that to get VFR assistance from any “radar equipped ATC facility” you need to be able to communicate (a radio helps) and controllers have to be able to identify you (a transponder really helps). Now that you know you can get assistance you now need to know how to operate a radio and a transponder. Conveniently, the AIM covers both subjects:

Radio Communications Phraseology and TechniquesTransponder Operation.

The Trouble With Transponders

As I’m looking for what the AIM has to say about VFR operations I stumble on this:

4-1-19(e). Code Changes1. When making routine code changes, pilots should avoid inadvertent selection of Codes 7500, 7600 or 7700 thereby causing momentary false alarms at automated ground facilities. For example, when switching from Code 2700 to Code 7200, switch first to 2200 then to 7200, NOT to 7700 and then 7200. This procedure applies to nondiscrete Code 7500 and all discrete codes in the 7600 and 7700 series (i.e. 7600-7677, 7700-7777) which will trigger special indicators in automated facilities. Only nondiscrete Code 7500 will be decoded as the hijack code.

That has nothing to do with what I was looking for (or this article) but it’s a nice tidbit of knowledge to stow away.

Back to what I was looking for: A common problem we have at the Center is pilots who forget to squawk VFR when they cancel or terminate their VFR advisories. A common problem with low-time VFR pilots is they seem to think that once ATC assigns them a code, the code belongs to them. Forever. Here’s how it usually happens.You’re getting VFR advisories. You see your destination, terminate your radar service and switch over to Unicom. But you forget to change your transponder to code 1200. When you depart the airport later (an hour, a day, a month later), you forget to check what code is in your transponder. If it’s set on 1234, the controller that sees it starts wondering who you are.

Computer Confusion

The computer “sees” it and starts “wondering” who you are too. Code 1234 may have been assigned to you as short as 10 minutes ago, but when you terminated your radar service, the controller entered a message in the computer telling the computer that he no longer needed that code. The computer was free to assign transponder code 1234 to another aircraft.All sorts of bad things can happen when you’re using an unassigned transponder code. Some of them can be amusing after the fact, but none of them are amusing as they are happening. Controllers don’t like it when the computer gets confused. They like it even less when they themselves are confused.

AIM 4-1-19(g). Transponder Operation Under Visual Flight Rules (VFR)1. Unless otherwise instructed by an ATC facility, adjust transponder to reply on Mode 3/A Code 1200 regardless of altitude.

Road Trip

Let’s take another one of my fictional trips in your favorite bug smasher. Let’s go from Greensboro, N.C., (GSO) to Asheville, N.C., (AVL) via the most trusted form of navigation: IFR. No, not Instrument Fight Rules; IFR as in “I Follow Roads.” Interstate Highway 40, to be exact. (Yeah I know it’s an old joke, but the readers in Germany haven’t heard it.)When you departed GSO, the tower handed you off to GSO Approach Control. GSO Approach put you on a 0145 beacon code. You climbed to your cruising altitude of 4,500 and everything is going just fine. Those who have paid attention in the past know what is going to happen about 30 miles west of GSO. Those that didn’t will just have struggle along.

“Cessna 12345 radar service terminated 30 southwest of GSO. Squawk 1200. Contact Atlanta Center on 125.15 for further advisories.”

Checking In

Welcome to my world. Assuming you’ve paid attention, your next course of action would go like this. You tune in to 125.15 and you listen. The first thing you hear is:

“… climb and maintain 8,000. Squawk 5145, contact Center this frequency. Clearance void if not off by 1630, time now 1615.”

You, being properly trained and all, listen for the other aircraft’s read back. But you don’t hear anything. Keep listening.

“Bizjet123 read back correct. Report airborne.”

Just because you can’t hear the read back doesn’t mean that one isn’t being given. The controller could be using more than one frequency, or the aircraft on the ground getting his clearance could be out of your range. Whatever the case, you don’t want your first transmission to “step on” someone else’s transmission.

Please Stand By

All is quiet now, so give it a try. Remember, keep it short and to the point, just like the AIM says:

“Atlanta Center, Cessna 12345 request VFR advisories.”Cessna 12345, Atlanta Center, standby.”

Not exactly what you were expecting was it? It’s such a simple instruction though. It’s amazing how many pilots mess it up. Half don’t even hear the “standby” and just start talking anyway. The other half never seem to be able to “standby” as long as a controller needs them to standby. Not you. You’re VFR and can wait a really long time. Right?

“Cessna 12345 squawk 3173 and go ahead.”Cessna 12345, a Skyhawk, I’m over I-77 following I-40 to Asheville VFR at 4,500.”

Well, that’s not terrible or anything, but remember what I said about Centers being set up to handle IFR traffic? The intersection of I-77 and I-40 isn’t exactly an IFR fix. Most controllers will know where it is but not all of them.

Location, Location, Location

Another thing that is unique about Center controllers is that most of them don’t live where they work. I live south of Atlanta, Ga. The airspace I work is mostly in North Carolina and Tennessee. Over the years I’ve learned a lot of the local landmarks. I know where Grandfather Mountain is, and Lake James. I know where I-40 is and I-77. The guy that transferred in from Memphis Center recently probably doesn’t, though.It’s not a big deal. Just something to keep in mind.

“Cessna 12345 radar contact 10 miles northeast of Statesville. Maintain VFR, Hickory altimeter 3012.”Altimeter 3012 Cessna 345.”

See? I told you it wasn’t a big deal. Even if the controller didn’t know where I-77 was he would be able to find you. It’s just faster if he knows where to start looking.

Comm Check

While we are here, have you ever stopped to analyze the structure of a check in? Obviously there is some information being passed, but have you ever thought about it being a “communications check”? Let me show you an example to explain what I mean.I had a King Air check in yesterday like this:

“Atlanta Center, King Air one one Alpha Alpha with you at ten.”

Ignoring the sloppy phraseology I replied:

“King Air one one Alpha Alpha, Atlanta Center roger, Hickory altimeter 3012.”

There was no reply. I thought that was kind of curious. I also had the sneaking suspicion that he heard me. So I called him back:

“King Air 11AA, Atlanta Center, how do you read?”Loud and clear Atlanta, 11AA.”

After browsing through the AIM I can’t swear to you that he’s required to answer me when I give him an altimeter. I know that I’m required to give him one. From the Controller’s Manual:

FAA 7110.65 2-7-2. ALTIMETER SETTING ISSUANCE BELOW LOWEST USABLE FLc. Issue the altimeter setting:1. To en route aircraft at least one time while operating in your area of jurisdiction. Issue the setting for the nearest reporting station along the aircraft’s route of flight:

And I could stretch it with a quote from the AIM:

4-2-3. Contact Proceduresc. Subsequent Contacts and Responses to Callup from a Ground Facility.You should acknowledge all callups or clearances unless the controller or FSS specialist advises otherwise.

Of course the AIM isn’t regulatory anyway. But if he reads back the altimeter correctly, I know that we have established good communications. I also know that he has his altimeter set correctly.

Altimeter Antics

I’ve seen a controller charged with an operational error because he didn’t catch that a pilot read back an incorrect altimeter. When that aircraft passed another aircraft with only 600 feet of altitude separation, instead of the required 1,000 feet, the “snitch machine” (Operational Error Detection Program) went off. I’ve seen TCAS RAs (Resolution Advisories) caused by incorrect altimeter settings. I’ve also been chewed out by a pilot (rightly so) for issuing him an old altimeter. The altimeter was six hours old and I didn’t notice. Fortunately the pilot did. The altimeter I gave him would have put him 300 feet low on an approach to an airport where the weather was 200 overcast.Have I ever mentioned that everything in this business is important?My how time flies when you’re having fun. Where were we? Oh yeah, following I-40. You ought to be approaching Hickory (HKY) by now. Your VFR cruising altitude of 4,500 puts you well above HKY’s traffic pattern and Class D airspace, so you don’t have to worry about that.

Right Height for Flight

I hope you’ve noticed that 4,500 is a correct altitude for your direction of flight (westbound). I can’t overemphasize how important it is to fly at the correct altitude for direction of flight. “East odd, west even” is almost second-nature for controllers. That simple principle has separated more airplanes than air traffic controllers ever thought about separating. There are a lot of people (including controllers) who don’t believe that. Trust me on this one. It’s one of the best habits you can have as a pilot.Something else I hope you’ve noticed. The interstate tends to go by a lot of airports. You’ve already passed SVH and HKY. The next one you’ll be approaching is Morganton (MRN). While 4,500 has put you well above the traffic operating around HKY and SVH, the approach into MRN starts at 5,000. The NDB at MRN (FIQ) is right next to I-40. So if you hear the controller working someone shooting approaches into MRN you can expect to have some traffic.

Be Aware

You’ve probably heard the term “situational awareness” used many times. The more you know about your route of flight, the easier it is to be aware. I don’t think I’d climb to 6,500 just to avoid MRN. That airport isn’t very busy and the odds are that you won’t meet any traffic shooting the approach on a VFR day.But if you look down the road just a little bit you’ll see some mountains. Are you going to climb to go over them? If you are, and you hear that someone is shooting practice approaches into MRN, then you might want to start your climb before you get to MRN. You don’t have to, of course. It’s just something for you to consider. It would be better to climb early than to wait until you are underneath the holding pattern at the NDB with traffic circling around at 5,000 and then try to climb.If you do elect to stay at 4,500, sooner or later you can expect to hear something like this:

“Cessna 345, be advised you’re entering an area where the minimum IFR altitude is 6,000”

As the phraseology suggests, this is just an advisory. You may elect to stay at 4,500, of course — you’re VFR. Once again you’re being confronted with the Center mentality. We know you’re VFR. We know you’re responsible for your own terrain avoidance.

Random Navigation

There are several factors at work here and they don’t lend themselves to any logical order so pardon me if I ramble a little. As a mentioned earlier, we don’t have a window to look out at the weather. It really wouldn’t matter — you’re 200 miles away. So we really don’t know what kind of weather you may or may not encounter. Even if we have some PIREPs for your area, weather changes. Just in case your forward visibility isn’t too good, we want you to know that you’re heading into higher terrain.Next, believe it or not, we have had a couple of instances where VFR pilots call us in a panic, telling us we had to let them climb. They were coming up on the mountains. This always vexes Center controllers. We don’t assign VFR altitudes. We can’t “let” you climb or “make” you descend. When you’re VFR in Class E airspace you can climb and/or descend at will. We like for you to inform us that you’re going to change altitudes, but just because we’ve acknowledged that you’re flying at a particular altitude doesn’t mean you can’t change to another one.Another factor at play is our limited knowledge of the terrain. Center controllers don’t work the same piece of real estate hour after hour, day after day. Obstructions and prominent terrain aren’t depicted on our radar scopes. The highest point east of the Mississippi, Mt. Mitchell, is in one of my sectors. I know where it is, but even it isn’t depicted on the radar scope. The point being, you may be flying over a valley but we can’t tell it. The Minimum IFR Altitudes (MIAs) are based on the highest terrain (or obstacle) in broad, irregularly defined areas. And that’s all we’ve got to work with.

Missing In Action

Last but not least, if you choose to stay at 4,500, we’re going to lose you on radar. We may lose radio contact with you also. That kind of defeats the purpose of getting VFR advisories, doesn’t it? MIAs aren’t based on radar and radio coverage. I wouldn’t count on staying in radar contact if you get too far below one, though. Especially in the mountains.OK, I lied. There’s one more thing you should consider. If you’re receiving VFR advisories and we lose you on radar, you can count on losing your flight plan too. If you’ll remember in a previous column I told you how Center controllers habitually put flight plans into the NAS computer for aircraft receiving VFR advisories. For those who don’t remember, this doesn’t have anything to do with a VFR flight plan you might have filed with Flight Service. That’s an entirely separate issue.

FAA 7110.65 5-2-9:b. Instruct IFR aircraft which cancel an IFR flight plan and are not requesting radar advisory service and VFR aircraft for which radar advisory service is being terminated to squawk the VFR code.

Do Over

If we can’t see you, we can’t provide radar advisories. Your radar service will get terminated and you’ll be told to squawk 1200. Once we do that, we’re supposed to remove the flight plan from the computer. That means the next facility down the road won’t know you’re coming. If you want to get VFR advisories from them (in this case, Asheville Approach), you’ll have to go through the initial contact procedures all over again. Which brings us full-circle, so to speak.I hope you’ve found something useful in this article. I know most pilots don’t follow roads in this day and age but we still occasionally get one. It’s always good for a laugh when a new controller wonders out loud why a VFR pilot is zig-zagging through the sky. Just another opportunity to use the “I Follow Roads” joke. I’ll see you again next month.Have a safe flight.

Don Brown
Facility Safety Representative
National Air Traffic Controllers Association
Atlanta ARTCC