Cessna one two three four five, what's your on-course heading?" How many times have you heard that little piece of phraseology lately? If you've flown out of a place where the controllers routinely assign you "Runway heading" (and who doesn't), I bet you've heard it a lot. So what does the phraseology mean?
Right now, dozens of controllers are saying, "What do you mean, Brown? Everybody knows what it means." Well, it turns out that "everybody" doesn't. I've had a half-dozen pilots write me and ask what it means. I thought I knew what it meant. But I like to quote "the book" when I give somebody an answer, so I looked in the book for the answer. After much searching, this is all I could find.
a. Used to indicate that an aircraft is established on the route centerline.
b. Used by ATC to advise a pilot making a radar approach that his/her aircraft is lined up on the final approach course.
And that's all it means. Does that definition fit with what you had in mind? Go ahead, do what most controllers do. Put on your jail-house-lawyer hat and see if you can make it fit.
First you'll notice that the definition isn't for "On Course Heading" so right off the bat you're headed down the wrong road. Those who are bound and determined to make the definition fit will have to go with definition "a" because there's no way that "b" is going to work. I'll let you mull that over for a while if you insist. The rest of us are going to move on. I'll shoot your theory out of the sky later.
For the pilots out there, let's start at the very beginning and take this step by step. Some of us are still learning and I want to make sure we don't lose anybody.
You have a Cessna 172 with GPS and you want to fly from Hickory, N.C., (HKY) to Logan County, W.Va., (6L4) You, like most general aviation pilots with GPS, have decided to completely ignore the filing requirements of the AIM 5-1-8(d) and have simply filed "HKY direct 6L4." This is what your flight plan will look like to the controller who will initially handle your flight plan:
N12345 (Aircraft ID)
C172/G (Type Aircraft)
110 knots (True Airspeed)
HKY (Departure Point)
P1200 (Proposed Departure Time)
70 (Requested Altitude 7,000)
HKY..6L4 (Route of Flight)
5134 (Beacon Code)
This information will be printed on a Flight Progress Strip 30 minutes prior to your proposed departure time and delivered to the WILKES sector at Atlanta Center (ZTL). The controller at this sector will (hopefully) take note of the strip in the proposal bay and call the flight plan in to HKY Tower. Hickory Tower doesn't have a FDIO (Flight Data Input/Output) so we do this the old-fashioned way: on the telephone. It goes like this.
ZTL: Hickory Tower, Wilkes, proposal.
HKY: Go ahead.
ZTL: November one two three four five, Cessna one seventy two, proposed one two zero zero, requesting seven thousand, Hickory direct six Lima four, beacon code five one three four.
HKY: Lima Alpha
ZTL: Kilo Charlie
Just because I know somebody will ask: All interphone (the FAA's way of saying "telephone") communications for controllers end with the participant's operating initials. In this case "L.A." is the controller at HKY Tower and "K.C." is the controller at ZTL. It makes it easier to track down the victims/culprits if something goes wrong.
It's important to note that the ZTL controller told the HKY controller that the destination was "6L4", not Logan County, W.Va. If the controller at HKY Tower doesn't look up the identifier, he won't have any more of an idea where "6L4" is than the ZTL controller does.
Chances are, when HKY Tower calls for a release on N12345, all the ZTL controller is going to say is "Released." The ZTL controller won't assign him a heading to fly or an altitude to maintain. That procedure is covered in a Letter of Agreement (LOA) between HKY Tower and ZTL Center.
LOAs are written documents that spell out procedures between different facilities/entities. LOAs cover all sorts of situations depending on the type of facilities/entities involved. Atlanta Center (ZTL) has an LOA with every facility on our border or in our airspace. For instance, the LOA between ZTL and CLT (Charlotte Approach) says that the arrivals on the SHINE STAR will cross the SHINE intersection at 11,000 and 250 kts. when CLT is on a south operation (landing south.) The LOA between ZTL and ZDC (Washington Center) says the RDU (Raleigh-Durham) turbojet arrivals over PSK will be on the SBV STAR and will cross the common boundary at FL270 or below. We even have LOAs with various military units spelling out how we will operate the different Military Operations Areas.
In this particular case, the LOA with HKY Tower says that the HKY departures will be assigned runway heading and an altitude of 4,000, unless otherwise coordinated. That's a phrase found in virtually all LOAs: "... unless otherwise coordinated." It gives controllers the flexibility needed to handle nonstandard situations. Take note that flexibility comes at a cost. You have to coordinate. Coordination takes time.
Back to the scenario -- it's time to fly. The ZTL controllers says, "Released," the HKY controller says, "Fly runway heading, climb and maintain four thousand," and he switches you over to the ZTL controller. You change frequencies ...
"Atlanta Center, Skyhawk one two three four five leaving one thousand six hundred climbing to four thousand."
"Skyhawk one two three four five, Atlanta Center, radar contact, climb and maintain seven thousand, Hickory altimeter two niner niner eight."
"Skyhawk one two three four five leaving one thousand eight hundred climbing to seven thousand, Hickory altimeter two niner niner eight."
Let's stop right here and see what we've got. Everything is marvelous at this point. You're airborne with no delay and climbing to your requested altitude. The only thing that is missing is a turn "on course."
That is the question the controller has to answer now. Where is "on course?" What does it look like? Does the pilot want to turn left or right, or continue straight ahead? If the controller didn't look up the airport identifier (6L4) he doesn't have a clue. Even if he did look it up he'd only have a vague idea that 6L4 is somewhere to the north.
What normally happens is that the Center controller will punch the ROUTE key and get the computer to tell him which direction 6L4 is from HKY. Terminal controllers don't have that luxury. Their computer systems won't draw a route line across the scope like the Center system will. For Center controllers, the function doesn't always work. Especially on an aircraft that the computer is just beginning to track. Sometimes you get an error message from the computer: "ROUTE NOT DISPLAYABLE."
What's a poor controller to do? If you want to turn left the controller will have to coordinate with CLT Approach. If you want to turn right he needs to know how far right you'll turn because he's got traffic east of you. I know what we can do. Let's make up some phraseology.
"Cessna three four five, what's your on-course heading?"
Please note the abbreviated callsign. The controller is now using less verbiage so he can have more time to ask questions. Hopefully some of my readers will remember I've advised against formulating questions when communicating via radio. There are no question marks (or any other punctuation) in verbal communications. There is only voice inflection. Voice inflection doesn't work well on scratchy radios and/or when English is your second language. So, if you wanted to make up phraseology (more) correctly it would be, "Cessna three four five, say on-course heading." But what the heck. We're just making it up as we go along so who really cares? I'll move on before I peg the sarcasm meter.
You're out there flying along on a heading of 240 degrees (runway heading) and the controller wants to know what heading you'd rather be on. What heading will take you direct to 6L4? Well, thinking from a pilot's perspective, that presents a dilemma doesn't it? If the truth be known, you really don't know what heading you need to fly to get to 6L4, do you?
For those who are having trouble deciphering the dilemma, think about the wind. It's March and the wind is howling out of the west. The pilot knows what track he needs to fly to Logan County, W.Va. -- 352 degrees from HKY -- but he doesn't know what heading he needs to fly until he turns towards Logan County and corrects for the wind to follow the desired track. Furthermore, that heading will change as the wind changes and even the desired track changes as the aircraft moves further and further southwest on the current assignment of runway heading (240 degrees.)
So what do you tell the controller? Beats me. He's making it up, so you might as will make up something too. I can tell you what he really wants to know. He wants to know that Logan County, W.Va. is a 352-degree magnetic bearing from the Hickory, N.C., airport. Well, what he really wants to know is the magnetic bearing to 6L4 from your current position. I guess that would depend on how long you've been flying runway heading and how fast you're going.
Back into the real (messy) world. When you hear, "What's your on-course heading?" the controller is asking you to take a swag at it. "Three hundred and fifty degrees" would be close enough for government work in this case.
For those of you still trying to make the official phraseology definition -- "on course" -- work, here's your downfall.
ZTL: Skyhawk three four five, what's your on-course heading?
N12345 : About three fifty, Center.
ZTL: Skyhawk three four five, cleared on course.
N12345: Cleared on course, three four five.
The controller really doesn't mean "on course." He really wants you to proceed direct to 6L4. If he really meant "on course" then you would have to get "established on the route centerline" of the course you filed -- HKY..6L4. Trust me, the controller really doesn't want you to reverse course, go back to HKY and then proceed direct 6L4 "on the route centerline."
Yes, I'm rubbing it in. Yes, I know that this procedure and phraseology are used thousands of times a day with no apparent problems. That is part of what I want you to notice. It is used thousands of times a day, yet no one questions its use. (Except for people unfamiliar with it and trying to learn the right way to operate in the ATC system.) Why?
Why do trainees (pilots and controllers) have to learn unofficial phraseology? Isn't official phraseology hard enough? Where are trainees supposed to go to learn unofficial procedures? The unofficial AIM? The unofficial FARs?
Let's go back a little so I can set you up. Just pretend I didn't tell you where 6L4 is. Let's also pretend you're a controller working a position by yourself and you've managed to get a little behind. You didn't see the proposal and HKY Tower calls asking about a flight plan for N12345. You scoot over to the empty D-side position and find the strip. You hurriedly read it to HKY Tower and he says the pilot is ready to go. "Released." You get back on the radio and say, "Calling Atlanta, say again, I was on the land line."
Time flies while you're having fun and N12345 calls. Geez, another airplane. You still haven't caught up (much less had time to look up the identifier 6L4) and N12345 is pestering you to turn on course. Blessedly, the ROUTE key works this time and you see N12345 wants to go to the north, about a 350 heading.
"Skyhawk one two three four five cleared ..."
Cleared what? Cleared where? You don't know the name of 6L4 so you can't say, "Cleared direct Logan County." You don't want to say "cleared on course" or "cleared direct destination" because that pain-in-the-butt who writes those columns for AVweb will talk bad about you. So what do you say? Hey, I've got it:
"Skyhawk one two three four five, cleared direct six Lima four."
(Let that busybody find something wrong with that.)
Let's say you've been doing that for years now. Again, there's been no apparent problems. "Cleared direct four Romeo four." "Hey Center, we're off Mike Romeo November going to November sixty two. Got time for some advisories?" That sounds pretty much like the chatter you hear on the radios these days, doesn't it? Yeah, you're right -- most people don't even bother using the phonetic alphabet. "We're off Em Are En going to En sixty two." That sounds more like it, doesn't it? OK, let's do that for a decade (without any problems) and the next thing you know we won't think anything about it because everybody does it.
"Hey Flight Service, I need a clearance from Ensee fifty two to Jayqueeff."
That reads funny, doesn't it? That's the problem with writing about verbal communications. What you hear and what you read are two different things. Hearing involves inflection, accents and (again) no punctuation. That's the reason I want you to read these next three quotes out loud. Go ahead. It won't kill you. People might look at you funny but take it from me, they'll get over it. Listen to what you read.
"Request clearance from En See fifty two to Jay Que Eff."
Did you hear that "two" and "to" sound just alike? That's what I mean about reading and speaking. They're not the same thing, nor do our brains process them the same way.
"Request clearance from November Charlie fifty two to Juliet Quebec Foxtrot."
It's slower and you feel kind of silly stating it that way, don't you? It sounds much clearer, though, doesn't it? Imagine trying to listen to it in a room full of people talking and radios blasting. Which would you rather try to hear? Let's try one more.
"Request clearance from Silver Creek to Concord."
Before you read any further, which one do you think is the most susceptible to misunderstanding? Read them all out loud again if you think it will help.
You won't believe this, but last month we had a guy depart NC52 going to Concord. The only problem was we thought he was departing N52. I don't know exactly what happened and I can't begin to count all the things that would have to go wrong for it to happen. But it did happen.
NC52 is Silver Creek, N.C. It's about 60 miles northwest of Concord, N.C., in Atlanta Center airspace. N52 is Jarrs -Townsend Airport in Waxhaw, N.C., in Charlotte Approach airspace. It's about 40 miles south of Concord. I bet it was interesting trying to figure that one out.
In case you've forgotten I was trying to make a point, let's imagine you were sitting on the ground at Silver Creek, N.C., and copying your clearance to Concord. Which one is more likely to grab your attention and set off the alarm bells?
A: "Cleared from En fifty two to Jayqueeff via direct ..."
B: "Cleared from Jarrs-Townsend to Concord via direct ..."
You can call me an old-fashioned, pain-in-the-butt busybody but I bet you'd choose "B." That's why I -- the controller -- am going to do my best to look up the identifiers and clear you to Logan County, W.Va., instead of 6L4. Hopefully I'll be able to figure out what the route looks like and I won't have to resort to making up phraseology to guess what your "on-course heading" might be. But if you'll file your flight plan in accordance with the AIM (this way), I won't have to guess. I'll know.
Have a safe flight.
Want to read more from air traffic controller Don Brown? Check out the rest of his columns.