Pilot Tip: Anticipating a precision approach clearance

[Keith Smith]

"N3AB, 5 from the marker, fly hdg 330, maintain 1600 until established on the localizer, cleared ILS RWY 30 approach, contact tower 118.30 at the marker."

Mouthful, right? Guess which part of that was news to us (ie, we had NO way of knowing it was coming).

*pause for effect*

Absolutely none of it.

When being vectored to the final approach course, ATC is legally obliged to do a few things when issuing an approach clearance (Reason #527,412 why it's good to understand why pilots can benefit from knowing how controller's do their job):
1) provide you with your position relative to a fix on the approach
2) an intercept angle of not more than 30 degrees (there are exceptions where it's 20, don't worry, they're rare)
3) an altitude to maintain until established on a published segment of the approach
4) an approach clearance.

Let's take 'em one at a time.

1) your current position just isn't all that interesting (this is a slight over simplification with regards to stepdowns outside the FAF, but for the purposes of digesting a rapid approach clearance, let's deal with what we can). Trust that the controller is not going to vector you to join inside the final approach fix (he/she can't do legally do that). In most cases, in the real world, you'll be flying with RNAV equipment, or will have a VFR GPS that gives you an idea of where you are (if you're truly interested).

2) add or subtract 30 from the final approach course heading (a number you HAVE to know as part of the approach brief, life sucks without it). It'll be one of the two numbers. For the ILS RWY 30, you're going to intercept on a 330 or a 270 heading 99% of the time. Which of the two? Depends which side you're coming from. Once the vectors start, it'll become obvious.

3) alright, this one can have some variation, but it's usually only if the controller's MVA for that area (minimum vectoring altitude) is higher than the minimum glideslope intercept altitude (the lightning bolt on the plate). For the ILS RWY 30 approach, you'll often be coming from over the ocean. I'd have to triple check the chart, but most oceans are close to sea level, so the MVA wont' be a factor. If worst comes to worst, you might get a different altitude. It'll be the ONE memory item for the whole clearance.

4) if the name of the approach comes as a shock to you, then [hilarious comment about poor piloting skills, implication to avoid operating heavy machinery, and suggestion to take up knitting instead]. Kidding aside, you will have the approach plate right in front of you, the name is right there just in case you forget.

5) in high traffic environments, it's standard practice for controllers to issue deferred frequency change instructions that are to be executed at the final approach fix. This makes the approach clearance long enough to freak most people out, and for the controllers to feel dynamic, wind swept and interesting. It also allows them to "set it and forget it" with regards to your flight. They can forget about you and move onto vectoring 4 other people at 4 other airports without coming back to LGB to give you a freq change to the tower. There are two types of freq changes to expect. They'll either issue it there and then, or tell you to do it upon reaching the final approach fix. The NAME of that fix had better not come as a shock, having briefed the plate, and having it right in front of you. (See reference #4 above). This is a BAAAAD time to begin blubbering about an FMS and not knowing how to look up legs. Have the plate out, it has what you need. The frequency itself is no shock, either. You knew the freq change to tower was coming at SOME point, and the frequency is not top secret information. In fact, you've PROBABLY already set that into COM1 stdby freq during the approach brief, so all that remains is to visually compare the number the controller issued with your com1 stdby freq.

So there it is...out of all that babble...the only thing we were MILDLY interested in was the ALTITUDE. Hold it in memory and read back, "three thirty, sixteen hundred 'til established, cleared ILS 30 approach, tower at [fix], [callsign]" There isn't a single word/number in that readback which wasn't important, and we left nothing critical out.

Good news...in cases where the assigned altitude matches the minimum glideslope intercept altitude, you can drop the altitude from memory after that and just use the plate. Confirm the 30 deg intercept angle by looking at the plate and you're golden...just fly it.

Practice...practice....practice. Eventually, you'll be able to read out the approach clearance, almost word for word, before the approach controller does it. I did this on my BFR (ILS to minimums in IMC into Atlantic City) recently, and my instructor nearly passed out when he found out I'd never flown to this airport before.

It's true, this stuff works! And why does it matter so much? Well...would you like to guess what my workload was in dealing with the vectors and the read back of the clearance? Nill. I was concentrating almost entirely on flying smoothly (important in IMC), managing my energy state, and visualizing the rest of the approach. If you stay ahead of the situation, you get to live.

Anyone doing it any differently?

[Mark Hargrove]

Keith,

Great post, great tip. The only thing surprising about the clearance to me was what airport I was landing at, but heck, you finally mentioned LGB and I figured it out...

I try to anticipate exactly as you've described, often making small bets with myself as to exactly when I'm going to hear the actual clearance, based upon my position relative to the localizer (or IAF for RNAV or VOR approaches).

One thing I've wanted to ask about and kept forgetting about is this: once I receive and read back the approach clearance (and I'm really thinking just about ILS approach clearances here), I will often slightly disregard the intercept heading I was given and turn to a somewhat more aggressive intercept angle -- 40-45 degrees perhaps -- especially if I've been turned in just a few miles outside the FAF. Am I being naughty by doing that, or is that within my discretion after being cleared for the approach? I've never had a controller grump at me, but I've sometimes wondered if that's OK.

-M.

[Ryan Geckler]

I will often slightly disregard the intercept heading I was given and turn to a somewhat more aggressive intercept angle -- 40-45 degrees perhaps -- especially if I've been turned in just a few miles outside the FAF. Am I being naughty by doing that, or is that within my discretion after being cleared for the approach?

Bad. You just violated a clearance, did you not? What if your heading intercepts you inside the FAF now, and the 30 would have worked perfectly? What if there was traffic in front of you and we are trying to get you at minimums?

I've never had a controller grump at me, but I've sometimes wondered if that's OK.

-M.

Now that I know you do that, I'll watch more closely...

[kullery]

Perhaps we need to consider this forum as a simulated report into the NASA Aviation Reporting System and thereby grant Mark immunity from prosecution for his admitted violation

Side note: I don't recall if it has been mentioned here before but if you are not familiar with the NASA Aviation Reporting System, check it out. The reports make for some fascinating reading and when flying RW, it's probably the first place you should go to confess after screwing something up.

[Alex Stjepanovic]

I will often slightly disregard the intercept heading I was given and turn to a somewhat more aggressive intercept angle -- 40-45 degrees perhaps -- especially if I've been turned in just a few miles outside the FAF. Am I being naughty by doing that, or is that within my discretion after being cleared for the approach?

Bad. You just violated a clearance, did you not? What if your heading intercepts you inside the FAF now, and the 30 would have worked perfectly? What if there was traffic in front of you and we are trying to get you at minimums?

I've never had a controller grump at me, but I've sometimes wondered if that's OK.

-M.

Now that I know you do that, I'll watch more closely...

On top of this, what if the controller constitutes that as the effect of a strong wind or compass error, and starts "anticipating the correction" with your further flying(if any at that time) and/or other traffic?

The whole point of IFR is positive control 100% of the time. ATC is a "control service", not a "suggestion service". Absolutely every bit of everything that goes on 100% of the time, is known 100% of the time. You wouldn't want the controller disregarding the separation minimums by bringing you a few miles into the protection area of terrain, obstacle or traffic, would you?

[Keith Smith]

Mark,

Sorry you got your head bitten off. Ryan, how on earth would a steeper angle have him intercept the localizer later? It's going to have him join earlier by definition.

I _should_ have done this once, but didn't. The controller issued a 30 deg intercept and because of the 40kt crosswind, the resulting COURSE was going to have me join inside the FAF. I requested "20 degrees to the right for a string crosswind" and he approved it.

That said, if one pilot flies a course, then the controller never knows about the crosswind and keeps assigning the dud heading all day long....so I guess it still holds true, you should fly the exact heading assigned by the controller and then request a different heading if requested.

You should resist the urge to set up a steeper intercept. The controller will have you join at a point that's appropriate, if not, make a stink, "verify this is going to have us join outside the gate?" That will get his attention.

Don't be squeamish...they should join you up at a reasonable. If they're NOT doing that, the solution is not to do your own thing. In an extreme case, Alex is right, your diversion could result in a loss of lateral separation. This would be a 1 in 10,000 event...but it's possible. Practically speaking you could do this for years and not have it be a problem, but the "right" thing to do is to fly the heading. If the resulting course isn't working because of the winds, say something. This is why I always have the GPS showing me my course and where possible, the BRG field when it's sequencing to the FAF. You'll know instantly by looking at that if the current course is going to have you join inside or outside the FAF (and yes, for a RNAV approach, simply joining AT the FAF is not good either, you want to be established outside of that so it will step down from TERM to APPR sensitivity).

[Ryan Geckler]

Mark,

Sorry you got your head bitten off. Ryan, how on earth would a steeper angle have him intercept the localizer later? It's going to have him join earlier by definition.

This is why I need to stop posting in the morning. My brain doesn't function.

[Mark Hargrove]

OK, I'll be a good boy from now on and follow directions.

-M.