While I appreciate your attempt to work out the math, it is not a representative of real traffic load as you'd think.

 

I don't think it's representative of real world traffic flow at all, what it does show is that per runway, those two airports are about as busy as each other. Neither one needs any "special treatment" with regards to traffic flow onto a runway as they are similarly loaded. Ergo, anticipated separation is not used/required because US airports are so busy.

 

It makes it easier on the controller because frequency use is made more effective.

 

Agreed, there are 2 less calls to make ("Bigjet 123 wind is 310 at 9 knots, cleared to land runway 31R" and "Cleared to land 31R, Bigjet 123") but I can't see that making the difference between a go around or not, especially given that most of these aircraft are multi crew so the guy doing the flying can react to the first call and let the other guy make the readback. I'm not sure I'd use the word effective but it certainly reduces the number of transmissions.

 

Additionally, it does actually make life easier for the pilot, even though people here seem to be ignoring that point.

 

I already gave my comment on that (so it's not being ignored - 1/3 of the way down page 3) and I disagree, I don't think it makes a blind bit of difference to the pilots. It may be easier for a pilot who just wants to hear the words "clear to land" but for any pilot who wants to know if the runway is safe to land on then, if anything, it's harder.

 

That last point, however, couldn't be further from the truth, and is really an uneducated statement. I'm pretty sure I have other adjectives for that, but I'll leave it there.

 

No idea what I said to push that "hot button", sorry if I upset you.

 

Please don't perpetuate the pilot versus controller mentality. It's already bad enough.

 

Was that aimed at me? I value controllers immensly and see no benefit in starting a turf war, let's just make sure we each know what each other is doing and what we mean when we say things. Any misunderstanding can be fatal (to the pilots at least).

 

The answer to the OP is still, it's just the way it is, there's no reason, it's always been done like that (and that doean't mean I think it's good/bad/dangerous/fun/silly/the best way/the only way/whatever, it just is).

 

All the best,

 

Ian

I stopped replying to this topic as it seemed my r/w experience was carrying no weight, but I thought I would reply to this.

 

Yeah. Seems like that's the case a lot of the time here, unless you have thousands of hours and a type rating. Never mind that this is an ATC issue, you work tower and I work closely with traffic management tools and TMUs across the country...

 

As far as the SKW accident, this is why major facilities now have the AMASS or ASDE-X. We had the AMASS and got upgraded to the ASDE-X about a year ago. If there is an aircraft, vehicle, etc on a runway that an aircraft is arriving, the system will alert the controller (the entire cab in fact) to send the arrival around.

 

Exactly. I was alluding to that in my earlier comments about the automation, but not having worked with ASDE-X, I didn't want to say what it did or didn't do as far as alarms go.

I don't think it's representative of real world traffic flow at all, what it does show is that per runway, those two airports are about as busy as each other. Neither one needs any "special treatment" with regards to traffic flow onto a runway as they are similarly loaded. Ergo, anticipated separation is not used/required because US airports are so busy.

 

I see your point, but again, 'busyness' is more determined by compression.

 

Say I work two facilities as a controller:

I work at a busy GA airport where aircraft departed consistently all day, and I see 1440 aircraft a day (1/min).

I also work at a busy field frequented by airlines, where aircraft arrive in banks, and also see 1440 aircraft per day.

 

The issue is that, at the GA field, the arrivals are spaced out evenly.

At the airline field, however, the banks mean that aircraft are arriving en masse within a particular time frame. All other times, it's relatively dead, or it's a departure bank.

 

Granted, I know we're meaning to compare major airline fields in the US and EU, but as I understand it traffic flows differently over there. With so many countries, and so many airlines going to several more large cities in closer proximity, the departure times are more evenly spaced than they are here, where everyone on the East Coast departs at roughly the same time to reach the 4 or 5 main West Coast destinations.

 

Agreed, there are 2 less calls to make ("Bigjet 123 wind is 310 at 9 knots, cleared to land runway 31R" and "Cleared to land 31R, Bigjet 123") but I can't see that making the difference between a go around or not, especially given that most of these aircraft are multi crew so the guy doing the flying can react to the first call and let the other guy make the readback. I'm not sure I'd use the word effective but it certainly reduces the number of transmissions.

 

Efficient frequency usage is a lot more than how many calls you make. I stated this earlier. Different transmissions and instructions by the controller carry more or less of a time sensitive nature, depending on the call. Through making more of those calls less time sensitive, it frees up time for more time sensitive calls.

 

Clearing someone for takeoff is time-sensitive. I need you to do this now (and if it's even more than simply now, I'll say 'expedite' or 'no delay', depending on the call).

Instructing someone to cross a runway is time-sensitive. I need you to do this now.

Clearing someone to land is not as time sensitive. I've flown into CHO (Class D airport - not too much traffic) a few times, and have been cleared to land about 20nm out (it has a CTRD). It's not a do this now type of instruction. It's a permission instruction (regardless of anticipated separation or not).

 

An instruction like that allows the tower to say "you know, there's nothing going on, let me let this guy know he has his clearance, and if someone needs to jump out, I can throw them outta here if the necessary separation is maintained."

 

I already gave my comment on that (so it's not being ignored - 1/3 of the way down page 3) and I disagree, I don't think it makes a blind bit of difference to the pilots. It may be easier for a pilot who just wants to hear the words "clear to land" but for any pilot who wants to know if the runway is safe to land on then, if anything, it's harder.

 

The only way I, as a pilot, know the runway is safe to land is when I look at it and see that the runway is clear, or that in my own view, it will be clear by the time I set my wheels down on it.

 

Ever.

 

Clearance to land is just that: I'm giving you permission to land at this facility. In a similar manner, a radar controller giving you a climb or a descent is permission for you to execute that action. Say a VFR target beings climbing and strays towards your path and I anticipate it might be an issue after you've been cleared to 6000. Was my instruction for you to climb to my SOP altitude of 6000 wrong? No. I had anticipated separation, and that separation will degrade if I don't do something else. I might do one of several things to avert the issue, but in any case, corrective actions are issued and everything's just fine.

 

If clearances were assurances of separation in every possible situation, your clearance on your IFR flight plan would be a 100% assurance that your entire route would be protected with no modifications, would it not? If I can't issue a landing clearance until I'm assured it's fully clear, the idea is that I have to ensure all flight paths are always deconflicted in the case of clearances. Am I missing something?

 

No idea what I said to push that "hot button", sorry if I upset you.

 

Was that aimed at me? I value controllers immensly and see no benefit in starting a turf war, let's just make sure we each know what each other is doing and what we mean when we say things. Any misunderstanding can be fatal (to the pilots at least).

 

I apologize. I took your comment about it only making it easier for the controller, and forgetting about [the flight] in a way other than you meant it. I took it to mean you were implying that the only purpose was to make their lives easier, and they'd just dispense with continuing to protect your flight because your clearance was given.

 

Sorry for assuming. It's a knee-jerk reaction, as I straddle the fence being both on the dark side, and out as a pilot, personally.

 

The answer to the OP is still, it's just the way it is, there's no reason, it's always been done like that (and that doean't mean I think it's good/bad/dangerous/fun/silly/the best way/the only way/whatever, it just is).

 

It really isn't. There's sound reasoning and judgment to give controllers the ability to conduct operations in a particular way. Without the proper safety mechanisms, or reasoning, we wouldn't be doing it.

 

Why did our wake turbulence minimums just get changed? Because we said so!

Actually, no, the reality is that it was studied and found that in many cases, wake turbulence separation was over-applied for many aircraft combinations.

Question, is anticipated separation used during low vis? If so how can the pilot ensure the runway is free when he can't see it?

Question, is anticipated separation used during low vis? If so how can the pilot ensure the runway is free when he can't see it?

During Low-vis, the runway and it's ILS system are protected. When running arrivals and departures I need to have my departure up and past the far end of the runway (past the localizer antennae) before the next arrival reaches 4nm. Once that arrival has landed, they have to be off the protected area of the runway (exits included where I work) prior to the next arrival reaching 4nm. I'm sure the rules vary regionally, but that's the simple explanation.

Question, is anticipated separation used during low vis? If so how can the pilot ensure the runway is free when he can't see it?

 

Good question.

The answer to your first question is that the 7110.65 does not specifically state situations in which is cannot be used, meteorologically.

 

To answer the second question, the pilot will still be able to see the landing environment in time to execute a missed approach, theoretically. In practice, your radar facility isn't going to be stuffing flights in at the radar separation minimums anyway (min is 3nm - which yields about 60 seconds between aircraft - plus wake turbulence additions), because of finals compression. Furthermore, if you were in CAT II or III, that spacing would further increase, both because of traffic management initiatives (TMIs) and natural filtering (a good number of aircraft aren't certed for those ops).

 

Additionally, if the facility has multiple runways, the arrivals would likely be stacked across for simultaneous approaches.

I for one completely agree with the fact that anticipated separation eases mental burden on both the pilot and the controller. And do not underestimate the importance of its effect on radio traffic: frequencies are so extremely busy, which itself is a safety factor.

Those who regularly land at LHR look at your GA ratio...

Question, is anticipated separation used during low vis? If so how can the pilot ensure the runway is free when he can't see it?

When flying into LGA, I can't recall hearing anticipated separation being used during low vis. When the weather gets low, traffic gets backed up. I normally get this type of separation during VMC conditions. I fly into LGA about 2 to 3 times a month and I usually end up on the expressway visual to 31. They use the expedite term alot when clearing guys for takeoff. I've been held at MIA and other airports when flying to LGA when the weather gets low. I've had to wait up to 2 hours. Also depending on the approaches being flown during low vis, you have to keep the critical area clear. There's a good little scenario that they teach about a controller being confused during low vis ops. She cleared a jet to depart when the runway wasn't clear. Luckily the departing crew sensed the confussion and denied the clearance until the controller was able to confirm the position of the other traffic. Could have been bad.

Hi,

 

There's a good little scenario that they teach about a controller being confused during low vis ops. She cleared a jet to depart when the runway wasn't clear. Luckily the departing crew sensed the confussion and denied the clearance until the controller was able to confirm the position of the other traffic. Could have been bad.

 

You mean

, right?

Thats it. They briefed this at flight safety during a quaterly sim. Here's another good one.

the pilot will still be able to see the landing environment in time to execute a missed approach

In true low-vis ops, pilots will be lucky to see 1000 feet in front of them let alone traffic a mile down the runway.

 

Where I work, multiple landing clearances can only be used while VMC conditions exist at the airport.

JFK ground "somebody didn't do something right" - "you can't just do....." [what the f** you want] hahaha.

JFK ground "somebody didn't do something right" - "you can't just do....." [what the f** you want] hahaha.

Lol, at least he kept composure. I like his tone and blowing of his breath lol.

"Virgin 491, follow to 757 ahead, you're number 405, cleared to land runway 34L"

Hahaha. Yeah, he did good in all fairness in my unqualified perspective.