I see from Wikipedia that, for aircraft landing, the separation should be at least 4 miles to avoid problems from wake turbulence. Is that not such a big problem or am I misunderstanding your comment?

 

It's true that there are separation standards, not at least 4 miles like Wikipedia states, it all depends on the aircraft types. However, we use visual separation to legally reduce separation standards. For example, if I have a 737 behind a 757, I need 4 miles, however, if I get that 737 to report the 757 in sight and instruct to maintain visual separation, it's now up to the pilot to determine how close he/she wants to get.

 

Standard IFR to IFR separation in our airspace is 3 miles (this does not include wake), but we have a waiver to reduce that separation on final to 2.5 miles without visual separation.

I guess the simple answer would be....we don't want it to be that way in the US.....

 

Fair enough, but can we then please bin the argument that the US airports would not work without anticipated separation?

 

 

Fair enough, but can we then please bin the argument that the US airports would not work without anticipated separation?

 

No, because whether or not you clear someone to land or not, ALL controllers use some form of anticipated separation....we just have an actual definition for it.

No, because whether or not you clear someone to land or not, ALL controllers use some form of anticipated separation....we just have an actual definition for it.

 

I thought that was the whole point of this discussion, in most of Europe we don't use anticipated/hoped for/dreamt/planned/prayed for/expected/imagined/wished for separation.

 

No clearance is issued until the separation is there, hence at LHR it's not uncommon to receive your landing clearance at 3 or 400ft with a guy 2.5 miles behind you.

 

And there can be just as much traffic per runway in Europe as there is in the US.

 

All the best,

 

Ian

in most of Europe we don't use anticipated/hoped for/dreamt/planned/prayed for/expected/imagined/wished for separation.

 

LOL I loved this part!

The UK has the world's busiest single runway airport (Gatwick) and the world's busiest two runway airport (Heathrow).

 

The only anticipated separation allowed is this paragraph:

 

Wake turbulence separation minima on departure shall be applied by measuring

airborne times between successive aircraft. Take-off clearance may be issued with an

allowance for the anticipated take-off run on the runway; however, the airborne time

interval shall reflect a difference of at least the required time separation.

 

Nowhere else in CAP493 is there any authorisation to anticipate separation. It still works, I can see why you do not want to change it because you are used to it and like it. But the system works without it.

Guys, nobody ever said the system would or would not work with or without anticipated separation. If someone said it, and I missed it, I'm sorry, but it certainly wasn't at all mentioned or inferred by me. If there's one thing I hate about discussions here on the forum is that someone has to drive an argument into black and white - will work, or will not work.

 

My making light of it causing issues is a simple fact of life. I said it is used in order to make traffic flow more efficient. Without it, our system will not fail, as others have mentioned, using the UK as an example. All I've been saying is that we've been able to consistently move traffic at a higher throughput because of it. We have some unique airspace here in the US, along with some unique challenges. Nowhere else in the world will you find four incredibly high traffic airports within such a close proximity (the farthest distance between any combination of JFK, LGA, EWR and TEB is 18nm). We take every possible advantage we can get currently and there are still large delays. I never said it wouldn't work without it, but I did say that any delay will ripple back and ZDC (Washington Center) and ZOB (Cleveland Center) are already given quite a task in the arrival banks into the NY Metroplex. Forcing them to absorb delays beyond what they already do can lead to some very bad days.

 

Here's an example of one of the other ways in which we're trying to get more throughput in the NY Area (sorry for it being Facebook only, but that's where the FAA posted it - if you can find it elsewhere, post a link):

https://www.facebook...151067714960757

 

Additionally, have a look here and start clicking on different options. As an example, use TEB ARR 19/DEP 24, EWR ARR 22L/11 /DEP22R, LGA ARR 22/DEP 31, and JFK ARR VOR/DME 22L / DEP 22R/31L. That's an almost ideal situation (I used the JFK selection to approximate their visual procedures from the east). There's a lot of traffic going into that area. Every last second counts. If you took anticipated sep out of the equation, it would still work, but you'd have to absorb that potential delay in the other facilities.

 

Just as a final thought I had as I was driving up to the airport last night:

So what some of you are telling me is that you'd never turn left at a busy intersection unless you had a green arrow, yes?

Imagine a busy intersection, and the signal is green, so a left turn across the busy lanes is legal. Do you wait for an adequate break in the traffic and turn (this question assumes you'll get at least one), or do you just wait until you get the green arrow, because your turn is now dedicated and protected?

 

If you ever turn left on a green light without a green arrow, you're using anticipated separation. You accept a slight risk in that the traffic space is not dedicated, but life is all about risk. If you don't like risk, build yourself a castle and become a shut in.

 

The UK has the world's busiest single runway airport (Gatwick) and the world's busiest two runway airport (Heathrow).

 

I've seen that mentioned a lot already, but there's a lot more to traffic flow management than runway numbers. While it's true that this discussion is centered on that concept - clearing an aircraft to land before the runway has been assured clear - having a busy runway doesn't mean you're using it efficiently.

 

Using conceptual numbers:

EGKK has the highest number of runway ops per period of time (argument's sake: 1 day) at 24

KLGA has the second highest number of runway ops in that same period of time at 23.

 

What happens if EGKK has all 24 operations spread out across those 24 hours, and KLGA's are all within one hour, three times a day?

 

Granted, I doubt it's that extreme, but the issue remains: it's not all about total runway numbers, it's the traffic load of those runways. I only have runway demand stats for the United States, so I can't compare them and make an argument in statistics. There's more information that needs to be gathered, however, beyond "busiest single runway in the world."

Sometimes anticipated separation works....sometimes it doesn't.

 

I was riding in the cockpit jumpseat on a 10 and clear day (aka VFR) into KSLC in a CRJ-900, we were 3 1/2 miles in trail of an A320 and we were cleared to land. As we approached 3 miles from the runway, the A320 was just crossing the threshold. As we got down to one mile and 1000ft AGL, the A320 had still not cleared the runway. About 10 seconds later, we got the order to go around.

 

On the second approach, we were 5 miles in trail of a CRJ-200 who was in trail of an A320. As we got down to 5 miles, I got this feeling of deja-vu. The A320 rolled long and the CRJ-200 got nearly to the threshold and executed a go-around. The A320 had still not cleared the runway as the CRJ-200 above him turned westbound into the pattern. By the time we got down to 1 mile and 1000 ft AGL, the 320 had cleared the runway and we landed without incident.

 

As we were taxiing back, we saw numerous other go-arounds...it was not a good day at SLC.

 

The situation presented itself due to a wind shift at KSLC which required a change of runway orientation. We were well over 30 minutes out when we got sent up toward OCS (Rock Springs) and then vectored in over Provo...we had planned an approach to the 34s and now we were landing on the 16s. If you have that situation and a lot of traffic, especially in an airport like KSLC, which butts up right against the western ridge of the Rocky Mountains, getting all the inbound traffic shuffled around to land on the correct runway has ATC running pretty hard.

 

In Europe, the solution is to have aircraft simply hold at fixes then proceed inbound. If you fly into Heathrow with any kind of regularity, you will find yourself doing at least one lap around some fix before you are vectored inbound to the airport. In America, holding does occur frequently, but it is much less anticipated than in Europe and consequently, requires a lot more planning if we even think that something will require a change.

 

The point I'm making is that both systems have their merits. Both have their challenges. Anticipated separation does work here even in heavy traffic situations because pilots are trained to anticipate which taxiway they will use for landing and then aim to vacate the runway at that point. If for some unforseen reason, say low level wind shear, that requires a higher speed on approach causing the pilot to miss a taxiway and roll longer, if they can't vacate, then the aircraft behind him will most certainly execute a go-around. In our planning, the possibility of a go-around is automatically factored into the fuel planning, so there rarely any fuel issues as a result of a go-around.

 

It isn't perfect, but it works most of the time...and it is safe.

 

David Lamb

FAA Licensed Aircraft Dispatcher

The point I'm making is that both systems have their merits. Both have their challenges. Anticipated separation does work here even in heavy traffic situations because pilots are trained to anticipate which taxiway they will use for landing and then aim to vacate the runway at that point. If for some unforseen reason, say low level wind shear, that requires a higher speed on approach causing the pilot to miss a taxiway and roll longer, if they can't vacate, then the aircraft behind him will most certainly execute a go-around. In our planning, the possibility of a go-around is automatically factored into the fuel planning, so there rarely any fuel issues as a result of a go-around.

 

It isn't perfect, but it works most of the time...and it is safe.

 

Exactly.

 

Thanks for that insight Dave. I don't hear from dispatchers often. Mostly it's just the ATC coordinators' take on what ya'll said. Is go around fuel actually planned specifically, or is it just included in some of your alternate/contingency calcs?

Kyle,

 

I don't think there's any doubt the system works, it has been moving millions of flights around the US very safely for years. The OP was just asking why.

 

A few people have tried the "it's because we're so busy" angle...

 

Because it makes airport capacity acceptable to the airlines. Without it, there would be double the amount of aircraft in line on the taxiway waiting to go along with a reduced arrival rate.

 

As far as clearing every aircraft to land, here at Las Vegas if we didn't, we would have a go-around every other aircraft and have to increase our spacing on final...which would cause delays in the chain.

 

Neither of these really work as we have the same runway utilisation (if not higher) here in Europe and don't use "anticipated" separation (although Paris CDG is an exception, to be fair, Paris CDG is *always* an exception!). So if the runway utilisation is the same then it won't cause any back log higher up the chain and no further complexities in busy TMAs.

 

I guess the answer to the OP is simply a mixure of "we've always done it that way" and "it ain't broke, so let's not try and fix it". Both are perfectly acceptable answers but let's not pretend there's any logic to it.

 

I would like to comment on your post from a few days ago though...

 

It not physically harder, no, but being held in suspense like that is, mentally. To me, it's a lot better to have an expectation and a contingency than it is to have nothing. In the case of anticipated sep, your expectation is that you're going to set down, with the contingency that you might have to go around. In the case of "continue approach" (not using anticipated sep), you don't have anything. You're waiting for either a clearance to land, or an instruction to go around. That delayed instruction places the pilot in a void of instruction. Continue inbound to the airport, but continue to wait for further direction.

 

As a guy who operates regularly into LHR and is quite used to getting late landing clearances, I'm struggling with the logic.

 

If you're not given clearance to land your expectation is to go around. Of course, you don't really expect to but that's the current instruction, continue your approach until MDA (or DH) then go around. There's no mental suspense, you don't have "nothing" and you aren't in void of an instruction, you have "continue approach", that means you continue the approach. It gives me a nice warm fuzzy feeling inside because if something happens to the controller, or comms (either his or ours) or anything else before we get there, we go around and people rarely die in go arounds.

 

I find it very unnerving operating into US airfields when they give us a "clearance" to land as I know it means diddly squat, indeed I know full well the runway isn't clear. While we're a few miles out it's no biggie but as we get closer, particularly if the weather's a bit dodgy, we really have to ask ourselves if the clearance is still valid or has our radio broke or is the guy on the phone, in the loo, broken his radio, talking to his assistant or dead!

 

We have no idea; and we're steaming in with all these people on board and just some 3rd party's "anticipated" safe runway. I know I'm used to the UK system so I'll naturally be more comfortable with it but I'd really rather just know for sure that the runway is safe "right now" (as I'm about to land on it), rather than "it might be soon but don't worry, I'll let you know... honest" (while I'm 10 miles out).

 

I find that much more stressful than having LHR say it's going to be a late landing clearance and just flying it manually down to 50/100ft waiting to hear the words (not forgetting the guy next to me will take the call) and then landing (or going around as appropriate - I never have).

 

It's also worth pointing out here that in the UK we have the "land after" clearance, which is a bit of a fudge but basically says that in certain conditions (by day, good vis, in sight of the guy in front) an aircraft can land on a runway while it's still occupied by another further along. It's almost as dodgy as LAHSO and is generally only issued to local operators (and usually the single aisle guys) but is very useful if someone has missed their exit and is dribbling up the runway to the next one. I've accepted them many times and never felt anyone was in danger - indeed in all cases by the time we'd actually touched down the "offending" aircraft was practically clear.

 

This is an interesting discussion as I've always wondered why the US issued it's landing clearances like that, I kinda figured out there wasn't really a reason but it's interesting to hear others thoughts.

 

All the best,

 

Ian

 

P.S. our SOP is to always plan for a diversion airfield (even when it's not legally required) and the fuel planning software calculates the fuel required from the point of initiating the go around, flying the MAP, then an enroute point, then a route including the anticipated STAR and approach and landing at the alternate. On top of that is some statistical contingency fuel so if a go around becomes necessary due to flow issues then fuel's normally not a big issue.

I fly world wide and have done more around the world flights in a single outing than i prefer too. I feel just as safe in the US as I do in any other airport around the world....well there are some places in the African Region that I find very unnerving and it isn't because of their radio clarity.

 

As far as landing clearances given while the runway is occupied, i'm sure there's a reason for it and it would take a ATC guy to explain why. In the aviation biz, things are usually done for a reason. I would'nt persuade or pretend that I know the reason because i'm on the other side of the fence. Through out my military and civilian flying life i've noticed that i've only been given this type of clearance at US heavy traffic laden airports during day time VMC conditions. During these times the traffic flows like clock work and reminds me of aircraft carrier excercises. I can say that when the weather is low, traffic backs up and they issue holding clearances instead of this type of landing clearance. We also have EVS so i can see the aircraft near the runway before we have them visually. Besides, they have to keep ye old ILS critical areas clear. Either way I've never ever had an issue with it and I all ways keep an eye on the guy/gal im following. I see this alot at LGA, MIA and SFO. I find it amazing how quickly one can forget if the landing clearance was given or not in the heat of the battle. You find yourself asking "are we cleared?" when things get busy. This is why I use the taxi light technique. As soon as you hear cleared to land, we turn on the taxi light. Now as i do my safety/configuration check i can glance up at the switch.

 

I haven't gone around in years while flying the line until last month while shooting the VOR into MHTG to get below a cloud deck. Every time i've gone, it was weather. I've never felt odd after a landing because of safety. I do know in heavy traffic areas you have to be on your A game and pay attention. Our SOP and techniques actually enhance our safety. I know it sucks to have to tune radios as you go along and keeping up with gross nav checks but it keeps you out of trouble. Backing up visual approaches with the ILS/FMS could have saved a few crews.

 

Bottom line I think there is a reason for many things. I may be a tad partial to the US because i'm a yank, but i treat all airports the same. I have never understood why in Europe I can't get my departure clearance before taxi like in the US. I prefer to know what i'm flying and how i'm departing instead of given a clearance while I taxi through an unfamiliar area. I've been given a departure clearance as i'm cleared for takeoff. Last thing i want to do is load/review/brief and setup a departure while on the taxi or taking the runway. But i'm sure there is a reason for it. I just use my best guest and after transiting through a few times, you usually figure the right one.

Rick

Is go around fuel actually planned specifically, or is it just included in some of your alternate/contingency calcs?

 

In the USA, for domestic flying, the fuel requirement is A- Fuel to destination airport. B- Fuel to furtherst alternate and C - 45min of holding at normal holding speed. That is the minimum required. On top of that, based on conditions, there may be an alternate airport added to the release. On top of that, we add fuel for unforseen contigencies (go-arounds, unanticipated holding) and weather conditions. Depending upon conditions, we may add it as "hold" fuel, which is part of the minimum fuel requirement for the flight or (in most cases), we add it as "extra" fuel. The upside of adding it to extra fuel is that it gives us the flexibility to burn some of it on the ground. If we put fuel into TAXI fuel, then we are required to burn it before takeoff, as it isn't part of the minimum fuel requirement. The other advantage to extra is that we can always move it to HOLD if the need arises on the fly as extra fuel is also not part of the minimum fuel required for a flight...but unlike taxi fuel, we can use it as needed airborne.

 

On a side note, I fly a lot on the simulator in Europe and am quite accustom to the clearance at the last minute concept. To the point that was made by Ian - you plan on going around unless you are giving a landing clearance. Couldn't have said it better myself. However, here in the USA, you are given a landing clearance, but pilots are trained to expect a go-around if the runway a- is not in sight and b- clear of obstructions by the MDA or DH (depending on the approach). The rule is for Cat I, if you can't land at the DH, you go around. In this respect, it isn't all that much different than in Europe...the pilot always plans for a go around (part of the approach brief) and on the approach, one pilot is heads down, the other is heads up looking at the runway.

 

Like I said, each system is different. They both get the job done....safely and that's what counts.

Happy New Year

Dave

225 pages of data on the runway use at Heathrow and Gatwick, for anyone interested in comparing it or just interested in general.

 

http://www.caa.co.uk/docs/589/ICF_runway_resilience_final_report_16Feb09.pdf

compare: "hold position" and "position and hold".

The difference is the order and the word "and". To a non naitive speaker this is not a very obvious difference. Now compare

"hold position" with "line up and wait"

 

There are no words in common at all, thereby the risk of confusion is virtually eliminated.

 

I don't see the downside of the change?

 

Yeah,

In the UK we have moved on further, we no longer say 'line up and wait' it is simply 'line up'.

 

 

The yanks are behind in a lot of regards, [Television image quality formats, etc.] But aviation is a pain for new long haul European pilots arriving into US airspace.

 

Celsius and Fahrenheit, lets not even go there! but I would like to see hector pascals being used in the states.

It's also worth pointing out here that in the UK we have the "land after" clearance, which is a bit of a fudge but basically says that in certain conditions (by day, good vis, in sight of the guy in front) an aircraft can land on a runway while it's still occupied by another further along. It's almost as dodgy as LAHSO and is generally only issued to local operators (and usually the single aisle guys) but is very useful if someone has missed their exit and is dribbling up the runway to the next one.

 

Interesting! I was wondering if this clearance was ever issued to airliners. I've only heard it a couple of times when flying GA out of Biggin Hill.

 

I have never understood why in Europe I can't get my departure clearance before taxi like in the US. I prefer to know what i'm flying and how i'm departing instead of given a clearance while I taxi through an unfamiliar area. I've been given a departure clearance as i'm cleared for takeoff. Last thing i want to do is load/review/brief and setup a departure while on the taxi or taking the runway.

 

Also interesting! In the UK I believe clearance is given before taxi (or even engine start) but that might be for SIDs only. Perhaps only non standard procedures are given at the hold?

 

The yanks are behind in a lot of regards, [Television image quality formats, etc.] But aviation is a pain for new long haul European pilots arriving into US airspace.

 

Celsius and Fahrenheit, lets not even go there! but I would like to see hector pascals being used in the states.

 

I'm only a low hour PPL, but I flew out in the states for the first time proper this autumn and found it to be a pleasure! Much more GA friendly (in terms of airspace). They were using Celsius too