Fly IFR, and you’ll run into this situation soon enough: You’re on a base-leg vector to the localizer or inbound course. This means you’re perpendicular to the final approach course—the course that takes you to the runway—and the next heading you receive from ATC should result in a 20- to 30-degree intercept to that final approach course. You should also get clearance to hold that heading until you join the final course and fly the instrument approach.
The catch is that a kickin’ tailwind has you screaming over the ground, and you can see the course needles for final course already moving toward center. You know you need to start the turn now, or you’ll overshoot.
However, ATC seems to have forgotten you and is currently talking to someone else.
Do you start the turn as you try to verify you’re cleared for the approach? Or do you hold your heading while trying to break in for the clearance, knowing you’ll blow through and need a new heading to re-intercept?
There’s a right and wrong answer per the regs, but it’s not so cut-and-dry in the real world. By the book it’s simple: You have not been cleared for the approach, so turning off your heading is a violation of FAR 91.123, unless you have good reason to suspect communications failure or it’s an emergency. By the book, you’re going to cross that inbound course.
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Breaking The Rules
In practice, however, we might exercise a bit more self-determination tempered by situational awareness. There are really two possibilities in this situation: One is that the controller got distracted and wants us to turn. The other is the situation has changed and the controller plans to vector us through the inbound course and has forgotten to tell us that. That last bit is important. Controllers must tell us if they want us to cross the inbound course. Something like: “Fly heading 360. Vectors through the localizer.”
Because the first situation is so much more likely than the latter, if the controller is busy with other aircraft, or if I’m at a remote airport where I know the little blip representing me is out in the back 40 of the controller’s scope, I’d start the turn. That’s me. I’m not saying that’s what you should do. Everyone’s situation is unique.
I’d also do my best to get a heads-up to the controller. The simplest technique is just pushing ident on the transponder. The “splat,” as it’s called, that appears on the controller’s scope is like waving at the waiter—and doesn’t require waiting for a break in radio communications.
Sometimes that doesn’t work, and the situation makes you concerned. If missing a turn inbound puts you on course to rising terrain or other traffic you can see via your avionics, you have a bit more justification for taking matters into your own hands. The last thing you want is for the controller to remember you just because a low-altitude or traffic alert went off in the control room.
Once coming back to my home airport in just such a situation, I could hear my Approach controller dealing with a pilot who was clearly flustered and having trouble on a day with low weather for miles around. I didn’t want to interrupt—and I could see the traffic on an opposite downwind—so I turned inbound and called Tower (while still monitoring Approach), explained what was going on over on Approach, and asked them to relay the information when it seemed appropriate. Tower paused for only a moment before relaying a clearance for the approach, a clearance to land...and a thanks.
Could I have gotten a phone number to call after landing instead? Sure. This decision carries risk. The consequence of obeying the letter of the law and flying through the localizer is usually only wasted time. I wouldn’t fault anyone for just trucking along and waiting. However, aviation is all about managing risk, so step one of dealing with this situation is trying to avoid it altogether.
Vectors To The Gate
Let’s back up a bit and review standard vectors for an approach. They resemble a large airport traffic pattern. There’s a downwind leg, which is displaced a few miles from the landing runway. Then there’s the base leg, perpendicular to the final approach course, which is (ideally) also the heading for the landing runway.
The next heading is the 20- to 30-degree intercept mentioned above. It’s usually accompanied by an approach clearance in the format controllers call PTAC, for “position, turn, altitude, clearance.” “Cessna Two Three Six Whiskey Papa, four miles from FIXIE, turn right heading 330, maintain 2800 until established, cleared ILS Runway 36 approach.” Sound familiar?
We think of this turn bringing us to the final approach fix, but it’s quite a bit outside of that point. Controllers use a point called an approach gate. The gate is a point at least one mile outside the final approach fix (or glideslope intercept) and no closer that five miles to the runway threshold. In practice, approach gates are commonly six or seven miles from the threshold. Vectors to final from a controller must intercept the final approach course two miles outside the gate, so that’s eight or nine miles from the runway threshold. Like I said, it’s a big traffic pattern, with an eight-mile final.
There are exceptions to that required distance. If the weather is good enough, ATC can cut the turn tighter but not closer than the gate. If the pilot requests an intercept that’s closer than normal, ATC can vector to intercept inside the gate but no closer than the final approach fix.
Back to the situation on the base leg with a tailwind. Part of a thorough approach briefing if you’re getting vectors should be what this base heading will be, so you can assess your closure rate when you turn on that heading. This is simple with a moving map or tablet. If you can, give map icon a track vector that shows where you’ll be in one minute at your current groundspeed.
Now watch the situation and, if necessary, be proactive. Suppose you see rapid closure while still a ways out on the base leg. You could preemptively request the final heading and clearance rather than waiting. “Portland Approach, Cirrus Two Fox Tango. Request heading 220 now to join the localizer and approach clearance.” Because you’re asking, the restrictions about distance outside the final approach fix are removed (including in bad weather). You could even try, “Approach, Cirrus Two Fox Tango. We’d like to turn ourselves onto the localizer when we’re ready. Request approach clearance now.” If you’re the only aircraft queued up for the approach, that just might work.
The prevalence of RNAV approaches means it’s common to get direct to a fix along the approach and a clearance instead of a vector. That works great if you’re approaching such that you can just continue inbound for the approach. Not so much if you’re on the downwind.
If you want to hit a point just (barely) outside the FAF, you could ask for a clearance direct to the FAF on an RNAV approach, but this isn’t exactly kosher. That’s not to say it can’t happen in the wild, but know you’re playing with fire if the controller allows it.
Here’s why. You should never enter direct to the FAF in your GPS. The GPS can’t do its pre-approach, signal-quality magic until it’s on a published leg of the approach. Direct-to does not count. If you enter direct-to the FAF, the GPS will wait until crossing that fix and then do its calculations to annunciate LPV or LNAV or even “approach unavailable.” It will also instantly change the full-scale CDI deflection from 1 NM to 0.3 NM or less. All this when you’ve just crossed the FAF and should be descending to a point hazardously close to the ground.
If you shouldn’t go direct to the FAF for an RNAV approach, what about activating vectors to final but requesting a vector to intercept inside the approach gate? No joy. Controllers are required to vector an aircraft at least two miles outside the approach gate for an RNAV (GPS) approach no matter what the weather and no matter what the pilot requests.
So, tip for the wise: If you’re approaching from the downwind side of the airport and want a tight turn at the final approach fix, request the ILS.
And when you get that vector, watch your rate of closure and anticipate that last turn. If you’re worried about an overshoot or want the freedom to make it yourself based on what your GPS tablet tells you: Ask for the turn and the clearance.
IFR Skills For VFR Pilots: Vectors To Final, VFR
VFR flight following can be the perfect tool when flying into unfamiliar airspace, especially at night. Sure, you have a GPS and the guidance is taking you directly to the airport, but finding the field can be an exercise in exasperation, even when ATC says, “Airport, 12 o’clock, five miles.”
Just as ATC can vector instrument aircraft onto the final approach course, they can vector your VFR flight into alignment on a long straight-in to the landing runway.
Suppose you’re 10 miles from the airport and hear that winds favor Runway 36. You could make this call:
“Bigtown Approach, Piper Two Six Three, request.”
“Piper Two Six Three, go ahead.”
“Piper Two Six Three requests vectors to a four-mile final Runway 36 at Bigtown Municipal.”
“Piper Two Six Three, no problem, fly heading three one zero.”
The controller has a top-down view and is a pro at vectoring aircraft. This is really no imposition at all to a controller used to aligning IFR aircraft all day long. Now you simply follow the instructions to get positioned on a long straight-in for the airport.
You can even ask for recommended altitudes if you want.