Vectors to Final
We practice full approaches and procedure turns. But in today's radar-dominated ATC environment, vectors to final is the way it's really done. There's a lot more to it than just holding a heading.
If you're like most instrument pilots, you spent a lot of training time flying full approaches, muddling through procedure turns while you tried to figure out just exactly where the final approach course really was. Unfortunately, all that training wasn't good practice for the real world; the full approach just isn't the usual way of doin' business.
Vectors to final is the way it's really done.
There's no doubt that full approaches are more difficult than simply following a controller's headings. But just because vectoring relieves you of getting yourself onto final, doesn't mean there aren't a few things you ought to be doing while the controller lines you up. There are some subtleties to being vectored and they change with the weather or a pilot's requests. Knowing a bit about the finer points can save you time and result in a cleaner approach.
First, let's look at the approach architecture from the controller's point of view, since he or she is doing most of the headwork on a vectored approach. A controller must consider a point in the approach that you won't find published on either Jeppesen or NOS plates. It's called the "approach gate" and it's defined in the pilot/controller glossary of the AIM as "an imaginary point used within ATC as a basis for vectoring aircraft to the final approach course."
On precision approaches, approach gates are generally established along the final approach course one mile from the outer marker (or another fix, in lieu of a marker) on the side away from the airport. For non-precision approaches, they're a mile outside the FAF. In either case, when measured along the final approach course, the gate will be no closer than five miles from the landing threshold. In some cases, they may be farther from the threshold.
Just how your vector relates to the gate depends on the weather. If the weather's good, the controller can vector you directly to the gate, but not inside it. For vectoring purposes, the FAA defines "good weather" as a reported ceiling and visibility of at least 500 feet above the minimum vectoring altitude (MVA) in the area you happen to be in plus a visibility of three statute miles. If no weather reporting is available, Pireps on ceiling and vis will do.
A "good-weather" vector to final should produce a groundtrack that will intercept the final approach course at an angle not greater than 20 degrees. Note the emphasis on groundtrack. To compensate for wind, the controller might assign a heading that will appear to result in an intercept of more (or less) than 20 degrees.
When the weather is less less than 500 feet above the MVA with less than three statute miles of vis, expect a vector to a point no closer than two miles outside the approach gate. In this case, the controller should provide a vector that will result in an intercept groundtrack that's no greater than 30 degrees. If it all works out, this should put you on final at least seven miles from the landing threshold. If you're a helicopter driver, the intercept angle can be up to 45 degrees.
Even though controllers try to correct their vectors for winds, it's been my experience that they don't always succeed. Remember, the controller is looking at a radar-enhanced depiction of your aircraft, not a real-time representation of where you are. This lag, and the fact that you're not the controller's only customer, sometimes results in a bad vector.
One case in particular comes to mind. I was flying from Tampa to Jacksonville's Craig airport (CRG) one rainy, windy night. The approach controller was vectoring me to final for the ILS 32 approach. I'd been battling 60-knot winds out of the northeast for the entire trip, so I knew that the wind correction angle on final would be truly impressive, perhaps in the neighborhood of 30 degrees.
I was on a heading of 050 degrees, 90 degrees off the final approach course. This heading, along with VOR, DME, and LORAN readouts, confirmed that I was on a base leg southwest of the airport and that I had a direct headwind. The mental warning flags were already popping up. I knew this monster headwind would quickly turn into a monster crosswind on final. All the ingredients were present for an undershooting vector to final. All it would take was a slight oversight on the controller's part.
Since the weather was lousy, I knew that I'd be vectored to a point two miles outside the gate and that the stiff winds would mean I'd need a heading of about 020 degrees to get the required groundtrack for a 30 degree intercept. Would the controller be sharp and give me a heading that would correct for the wind?
"N1161X, three miles from ADERR, turn left heading 350, maintain 2,000 feet until establised, cleared for the ILS runway 32 approach."
I knew right way that this heading would never intercept final; it would only parallel it. (See Paul Bertorelli's "Double-Checking the Vector.") So, acting as the final authority, I let the controller know that because of the wind, I'd need 020 degrees to intercept. The heading was approved as requested and the approach was completed.
Say the magic words
Okay, so we know that if the weather is a certain ceiling relative to the MVA, we'll get a longer trip down final. But how do we to tell what the MVA is? Unfortunately, only the controller knows for sure since he has above his radar screen a chart depicting all the MVAs in his area. Absent the chart, use the procedure turn or glideslope intercept altitude as a guide to the MVA. It should be relatively close. If you're really hard-over on the MVA issue, contact the plans and procedures specialist at your local ATC facility and request a copy of that facility's MVA chart.
About the only sure fire way to know where you're being vectored is to be cognizant of the visibility. If it's reported as less than three miles, you'll be going the long way around, two miles outside the gate.
There are some some things that we pilots can do to speed up or slow down the vectoring process. But as with other aspects of the ATC-pilot relationship, we have to ask. Controllers can't offer.
Let's say you're flying into your home drome and the visibility is reported as two-and-a-half miles. Bingo. Plan on a seven mile final. But you've flown the approach hundreds of times before, and you're familiar with the local terrain and obstructions. To shorten up the final, simply tell the controller that you'll accept vectors inside the approach gate.
This allows the controller to vector you to a point not closer than the final approach fix, with an intercept angle of not greater than 20 degrees. Depending upon your direction of flight, this trick could easily save you seven or eight miles of vectoring. Of course, your request has to fit in with the controller's overall sequencing plan. He won't be able to give you close-in vectors if they'll violate minimum separation standards with another aircraft.
On the other hand, even if the weather is good but you've dropped your timer, misplaced the plate or are otherwise trailing on static wicks, you'll want to slow things down. Just tell the controller that the approach will be "coupled" or "evaluated," or words to that effect. You'll then get vectored to a point at least two miles outside the approach gate.
It may take a couple of requests to get the message across, however. As an F-16 flight examiner for the Air Force, I frequently fly evaluated approaches. Earlier this year, I was giving an instrument checkride to a pilot in Great Falls, Montana. The weather was good and the vectors were resulting in tight turns to final.
I wanted to see an approach that would approximate actual instrument conditions, so I had the examinee inform the controller that all subsequent approaches would be "evaluated approaches." Approach rogered our call but the next vector was as tight as the first.
Obviously, we weren't communicating. During climbout I informed the controller that the next approach would be an "evaluated, coupled approach," and I'd like vectors two miles outside the gate. It didn't matter that the F-16 can't fly a coupled approach. All that mattered was that I used the magic words, all of them. It worked.
There's one instance when a request for a tight vector will not be honored. An aircraft is supposed to be vectored so that it will not intercept the localizer above the glideslope. In designated mountainous terrain, that restriction, coupled with the high MVAs in mountainous areas can mean that the approach gate is quite a few miles from the FAF. In these circumstances, the controller just won't be able to get you any closer to the gate.
Heed the clue bird
When it comes to the radio, pilots are lucky; we can use just about any phraseology we want. Controllers, technically speaking, aren't as fortunate. Their words are very strictly prescribed by the Air Traffic Control Manual (7110.65). And every so often, an FAA boss listens in to evaluate how a controller is speaking.
If a controller, for example, sees that an aircraft is well off course while inside the approach gate, he has no option other than to say: "N12345, X miles from the airport, X miles right/left of course, say intentions." These words are spelled out for him, crystal clear.
They should be just as clear to you should you ever hear them while on final approach. The clue bird is hammering desperately on your windscreen. The controller is saying everything within his legal limits to let you know that this particular approach is not going well for you. When the controller asks for your intentions, request vectors around for another approach. When things have gone that far awry, they seldom get any better. Take the hint. This is one birdstrike you'll be thankful for.
Vectors across final
What should you do if the controller forgets about you and drives you across the final approach course without clearing you for the approach? The controller's manual is very clear on this point, too. The controller is required to inform a pilot if a vector will take him across final, along with the reason. Something like this; "N12345, expect vectors across final for spacing." But, if for some reason the controller is unable to inform the pilot, the pilot is not expected to turn inbound on the final approach course.
While receiving vectors, the headings that you're given, in conjunction with what your avionics tell you, will give you the position awareness you need to anticipate the controller's next action. If that 30 degree intercept heading
isn't accompanied by the approach clearance or a reason to expect vectors across final, it's time to launch your own clue bird. Speak up early and often. Ask the controller if you're to expect vectors across final or if you're cleared for the approach. Make your communication clear, timely, and definite. Clue birds fly equally well in both directions.