U.S. ATC question

[Northbeach]

Too often we are told to slow down and/or given vectors when we are coming up on an arrival fix. If you have 5 or 6 jets coming in why not just assign each jet a crossing time over the fix? Say you need 6-8-10 miles or 2-3-4 minutes then the fist jet gets XYZ @ 00:00, the second jet gets XYZ @ 00:02 or 03 depending on ground speed and so on. 200 miles out you could assign virtually any FMS A/C a crossing time and save yourselves a lot of headaches? Seems too simple, what am I missing here. With the changes in technology why are we still doing things like we did 25 years ago?
This question isn’t to be interpreted as an assault on anybody’s competence as that is not my intent at all. I just don’t get it……… You are working an arrival sector and have crossing times why not just assign those times to us rather than waiting until we are 40nm from the fix then vectoring us around the sky?

[Chilli Monster]

The Controller 200 miles out isn't working arrivals 40 miles out, has no idea what their requirements are for spacing and is too busy doing his job to be doing their job as well.

Could you have used a bigger font?

[elcrusoe]

Well to be honest i truly believe this is already being done. Of course this is not a wide spread exercise. I personnally have seen this in use at 2 different locations, here in the US and overseas. The technical term we use in the air traffic control world is metering. The technology is here, in most all center facilities i would imagine. The use of CFR (call for release), EDCT's have evolved in this way. But nothing is perfect, adjustments have to be made all the time. Too many factors come in to play to have a perfect world. But don't just put the blame on the ATC, look a little at the airline schedules, there is only one 10000' piece of concrete for u to land on at one time but everyone wants it at the same time.

Hopefully a combined effort form the aviation world (if we ever start talking to each other and not pissing on each others back) and well some smarter then the average monkey managment things could change.

[Hold West]

Probably in part because controllers still have to keep the aircraft separated before the fix, and letting them achieve the crossing time however they want will result in conflicts before hand.

Second, from years of difficult experience, if there's only 40 miles to work with, and a line of aircraft to sequence, speed alone won't do it, ever. The situation calls for vectors, too.

That type of solution is perfectly workable in a more strategic setting, but for down-and-dirty tactical sequencing, it's just not going to work.

Since you directed this at US controllers, is there somewhere in the world that does do this, successfully and on a routine basis?

[Fly3]

Changi Airport in Singapore has been using this for some time during busy periods and it seems to work for them. The only holding I've ever experienced has been when the field was closed due to weather however, major radar vectoring can take place.

[Oosik]

Because the FAA is still using 25 year old technology and the US airspace system in some sectors is attempting to handle more than twice the traffic flow with the same equipment and procedures.

There is the technology and the systems do exist, just not within the FAA ATC realm.

Excited about changing that? Then privatise the system and get rid of the GS16 and above managment. Do you know of any US government entity that operates as a corporation and is profitable?

Get rid of the lardasses and then we can do something. I'm twice as fustrated as you and you can fly away. I have to work these antiquated systems.

[Northbeach]

Chilli monster – I cycle between several computers depending on which version of Word I am using the font changes when I post- sorry I pissed you off visually.

200 miles out / 40 miles out….. were just estimates. I’m not sure of the exact distances. My point was being with the same controller for a long time then coming up on a fix and being vectored at the last moment; why not give us a crossing time 15/20 minutes earlier.

Yes it seems it is being done elsewhere, although I fly predominantly in the USA.

Thanks to those of you who stuck through the weird font to answer the question. It seems it is possible but not with old equipment and old ways of doing things.

[ATCO1962]

Hey, Northbeach,

Your theory about crossing a fix at a particular time sounds great but in reality, doesn't work very well, at least, not in our airspace.

A number of controllers here use the technique and wonder why it breaks down. A number of reasons; firstly, not everyone is exactly using the same time, to the second, and seconds are important if you have to achieve an exact distance between aircraft. I would think that as we're all supposed to be using satellite time, in the future, that particular problem will slowly ease as we should all be using the same time reference. However, giving out the times up to the second will be necessary.

Secondly, it used to be the case that pilots had to be accurate in timekeeping to plus or minus 30 seconds. That means that, if you thought you were going to have 2 minutes separation i.e. about 10-12 miles at average speeds, you may only have 5-6 miles if the first aircraft turns up 30 seconds later than you thought and the second guy 30 seconds faster.

Most people here use a combination of speed and vectors.

Safe flying

[BelArgUSA]

I never had spacing for arrival problems in the USA.
Despite a "25 yrs old" ATC system, controllers are helpful and competent.
Even high altitude controllers are great in suggesting speeds prior to arrival.
xxx
Chicago, Atlanta and Dallas have an incredible amount of traffic.
And they do an outstanding job at getting everyone on the approach.
Giving arrivals an expected "time" for a fix on approach would be murder.
I have flown into JFK, ORD, SFO, LAX and MIA hundreds of times.
Not half of the concerns of doing an arrival to LHR or LGW.
In Europe, I rather take FRA or AMS any day, any time. Even CDG/ORY...
xxx
:ok:
Happy contrails

[GetTheFlick]

Northbeach,

You've already been given the good answers. It is called "metering" here in the States and it would work. As a matter of fact, we could make it work right off the ground. If...

All pilots would fly at the speed listed in their flight plan.

Airlines only flew one type aircraft.

There were never any thunderstorms or other weather.

Departures could sit "in position and hold" for a precise time to depart.

Of course, with the first go around, the first blown tire, the first missed high speed taxiway -- the whole day and the whole plan would be shot.

Not to worry though. The eggheads will keep talking the managers into spending billions of dollars by telling everybody that it will all work -- someday.

Don Brown

[Gonzo]

BelArgUSA,

I'd be interested to know what concerns you have about coming in to LHR, could you expand?

[Blockla]

Additionally, what makes you think the sequence is "stable and organised" when you are 200NM out. Departures departing from inside 150NM away will push in in front (possibly), then there are a whole lot of reasons why the arrivals sequence changes, from RWY config changes (which changes the acceptance rate and possibly the whole order of arrivals, to Medical (or other) priority traffic.

The concept of "time over a point" is great, but is subject to much amendment and inaccuracies as stated above. Getting to the fix is also difficult in certain circumstances due to separation issues.

From a pilot point of view would you be happy with a fix time, then still be subjected to (further) reduced speeds and vectoring; or would you simply prefer the suck it and see approach and possibly encounter no delay at all?

[FlightDetent]

My aircraft is not on the edge of computing technology, but pretty much a common view. The FMS' fix / time input field is one minute, give or take 30 seconds. Over such 60 s spread she will travel 7,5 NM (450 kt GS) in cruise, 6 in descent and 4 for initial approach. What use is then average 5 miles uncertainity boundaries for ATCO with 5 NM spacing?

FD (the un-real)

[anotherthing]

Gonzo

as both you and I know, there are problems with Heathrow and often Gatwick, but that's because of the limited tarmac time available for the amount of aircraft they handle. The busiest single runway airport in the world and the busiest international passenger airport in the world...

Couple that with (a small piece) of airspace that also has to sequence arrivals and departures for Luton, Stansted, City, Southampton to name but a few, and the initial sequencing for Birmingham and East Mids and there will always be problems!!

BelArgUSA

For Heathrow to work efficiently and maintain the runway occupancy percentage it does, it needs to have aircraft in the hold, so that the best sequence can be achieved.

Of course, if Heathrow could go to true 24 hour operations and the airlines spoke to each other and divided up the slots so they didn't all want to get to the same place at the same time, then that would help solve the problem, but as it is customer driven, the airlines won't do that...

The other option is stop growth at Heathrow and Gatwick and close all other airfields in the LTMA...