Vectors to Final

If you're like most instrument pilots, you spent a lot of trainingtime flying full approaches, muddling through procedure turnswhile you tried to figure out just exactly where the final approachcourse really was. Unfortunately, all that training wasn't goodpractice for the real world; the full approach just isn't theusual way of doin' business.

Vectors to final is the way it's really done.

There's no doubt that full approaches are more difficult thansimply following a controller's headings. But just because vectoringrelieves you of getting yourself onto final, doesn't mean therearen't a few things you ought to be doing while the controllerlines you up. There are some subtleties to being vectored andthey change with the weather or a pilot's requests. Knowing abit about the finer points can save you time and result in a cleanerapproach.

First, let's look at the approach architecture from the controller'spoint of view, since he or she is doing most of the headwork ona vectored approach. A controller must consider a point in theapproach that you won't find published on either Jeppesen or NOSplates. It's called the "approach gate" and it's definedin the pilot/controller glossary of the AIM as "an imaginarypoint used within ATC as a basis for vectoring aircraft to thefinal approach course."

On precision approaches, approach gates are generally establishedalong the final approach course one mile from the outer marker(or another fix, in lieu of a marker) on the side away from theairport. For non-precision approaches, they're a mile outsidethe FAF. In either case, when measured along the final approachcourse, the gate will be no closer than five miles from the landingthreshold. 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 directlyto the gate, but not inside it. For vectoring purposes, the FAAdefines "good weather" as a reported ceiling and visibilityof at least 500 feet above the minimum vectoring altitude (MVA)in the area you happen to be in plus a visibility of three statutemiles. If no weather reporting is available, Pireps on ceilingand vis will do.

A "good-weather" vector to final should produce a groundtrackthat will intercept the final approach course at an angle notgreater than 20 degrees. Note the emphasis on groundtrack. Tocompensate for wind, the controller might assign a heading thatwill appear to result in an intercept of more (or less) than20 degrees.

When the weather is less less than 500 feet above the MVA withless than three statute miles of vis, expect a vector to a pointno closer than two miles outside the approach gate. In this case,the controller should provide a vector that will result in anintercept groundtrack that's no greater than 30 degrees. If itall works out, this should put you on final at least seven milesfrom the landing threshold. If you're a helicopter driver, theintercept 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 youraircraft, not a real-time representation of where you are. Thislag, 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 Tampato Jacksonville's Craig airport (CRG) one rainy, windy night.The approach controller was vectoring me to final for the ILS32 approach. I'd been battling 60-knot winds out of the northeastfor the entire trip, so I knew that the wind correction angleon final would be truly impressive, perhaps in the neighborhoodof 30 degrees.

I was on a heading of 050 degrees, 90 degrees off the final approachcourse. This heading, along with VOR, DME, and LORAN readouts,confirmed that I was on a base leg southwest of the airport andthat I had a direct headwind. The mental warning flags were alreadypopping up. I knew this monster headwind would quickly turn intoa monster crosswind on final. All the ingredients were presentfor an undershooting vector to final. All it would take was aslight oversight on the controller's part.

Since the weather was lousy, I knew that I'd be vectored to apoint two miles outside the gate and that the stiff winds wouldmean I'd need a heading of about 020 degrees to get the requiredgroundtrack for a 30 degree intercept. Would the controller besharp and give me a heading that would correct for the wind?

I knew right way that this heading would never intercept final;it would only parallel it. (See Paul Bertorelli's "Double-Checkingthe Vector.") So, acting as the final authority, I let the controllerknow that because of the wind, I'd need 020 degrees to intercept.The heading was approved as requested and the approach was completed.

Okay, so we know that if the weather is a certain ceiling relativeto the MVA, we'll get a longer trip down final. But how do weto tell what the MVA is? Unfortunately, only the controller knowsfor sure since he has above his radar screen a chart depictingall the MVAs in his area. Absent the chart, use the procedureturn or glideslope intercept altitude as a guide to the MVA. Itshould be relatively close. If you're really hard-over on theMVA issue, contact the plans and procedures specialist at yourlocal ATC facility and request a copy of that facility's MVA chart.

About the only sure fire way to know where you're being vectoredis to be cognizant of the visibility. If it's reported as lessthan three miles, you'll be going the long way around, two milesoutside the gate.

There are some some things that we pilots can do to speed up orslow down the vectoring process. But as with other aspects ofthe ATC-pilot relationship, we have to ask. Controllers can'toffer.

Let's say you're flying into your home drome and the visibilityis reported as two-and-a-half miles. Bingo. Plan on a seven milefinal. 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'llaccept vectors inside the approach gate.

This allows the controller to vector you to a point not closerthan the final approach fix, with an intercept angle of not greaterthan 20 degrees. Depending upon your direction of flight, thistrick could easily save you seven or eight miles of vectoring.Of course, your request has to fit in with the controller's overallsequencing plan. He won't be able to give you close-in vectorsif they'll violate minimum separation standards with another aircraft.

On the other hand, even if the weather is good but you've droppedyour timer, misplaced the plate or are otherwise trailing on staticwicks, you'll want to slow things down. Just tell the controllerthat the approach will be "coupled" or "evaluated,"or words to that effect. You'll then get vectored to a pointat 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 flyevaluated approaches. Earlier this year, I was giving an instrumentcheckride to a pilot in Great Falls, Montana. The weather wasgood and the vectors were resulting in tight turns to final.

I wanted to see an approach that would approximate actual instrumentconditions, so I had the examinee inform the controller that allsubsequent approaches would be "evaluated approaches."Approach rogered our call but the next vector was as tight asthe first.

Obviously, we weren't communicating. During climbout I informedthe controller that the next approach would be an "evaluated,coupled approach," and I'd like vectors two miles outsidethe gate. It didn't matter that the F-16 can't fly a coupledapproach. 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 notbe honored. An aircraft is supposed to be vectored so that itwill not intercept the localizer above the glideslope. In designatedmountainous terrain, that restriction, coupled with the highMVAs in mountainous areas can mean that the approach gate is quitea few miles from the FAF. In these circumstances, the controllerjust won't be able to get you any closer to the gate.

When it comes to the radio, pilots are lucky; we can use justabout any phraseology we want. Controllers, technically speaking,aren't as fortunate. Their words are very strictly prescribedby 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 offcourse while inside the approach gate, he has no option otherthan to say: "N12345, X miles from the airport, X miles right/leftof course, say intentions." These words are spelled outfor him, crystal clear.

They should be just as clear to you should you ever hear themwhile on final approach. The clue bird is hammering desperatelyon your windscreen. The controller is saying everything withinhis legal limits to let you know that this particular approachis not going well for you. When the controller asks for your intentions,request vectors around for another approach. When things havegone that far awry, they seldom get any better. Take the hint.This is one birdstrike you'll be thankful for.

What should you do if the controller forgets about you and drivesyou across the final approach course without clearing you forthe approach? The controller's manual is very clear on this point,too. The controller is required to inform a pilot if a vectorwill take him across final, along with the reason. Something likethis; "N12345, expect vectors across final for spacing." But, if for some reason the controller is unable to inform thepilot, the pilot is not expected to turn inbound on the finalapproach course.

While receiving vectors, the headings that you're given, in conjunctionwith what your avionics tell you, will give you the position awarenessyou need to anticipate the controller's next action. If that 30degree intercept heading

isn't accompanied by the approach clearance or a reason to expectvectors across final, it's time to launch your own clue bird.Speak up early and often. Ask the controller if you're to expectvectors across final or if you're cleared for the approach. Makeyour communication clear, timely, and definite. Clue birds flyequally well in both directions.