'Time based separation' at Heathrow a world first
NATS Newsbrief - February 2014

 

I ran across this news release regarding longitudinal separation during high headwinds. It adds another complication to this issue and another set of standards that pilots must be aware of.

 

http://www.nats.aero/newsbrief/time-based-separation-heathrow-world-first/

 

It seems to be an elegant solution to airport crowding based on the physics alone. Think of it, distance separation based aircraft type and wake vortex that doesn't take headwinds into account results in slower arrival rates because the aircraft's speed over ground is inversely related to headwind velocity. As the headwinds increase in velocity the aircraft maintaining a constant IAS will see a decrease in SOG and a resultant increase in arrival times. According to the NATS, landing rate, passenger arrivals or whatever quantitative metric is used decreases causing delays and even cancelled flights.

 

The new system being deployed at Heathrow beginning in spring of 2015 will use data collected and studied over three years taken from over 100,000 flights. The resultant metric is expected to save over 80,000 minutes of delays every year. NATS is a partner in SESAR, the European Commission's equivalent to NEXTGEN.

 

 

I ran across this news release regarding longitudinal separation during high headwinds. It adds another complication to this issue and another set of standards that pilots must be aware of.

 

...at Heathrow.

 

Nobody else uses that yet, from what I know, and it's not so much something a pilot would really need to worry about. It's all a burden on the ATC side, just like wake turbulence separation (most pilots don't know the specific variable distance requirements between wake categories for leader/follower - they just know that they should avoid wake areas and heavy is theoretically more violent than small). Along those lines, TBS is really there to address delays and effective decreases the distance between aircraft. Despite the decrease in actual longitudinal separation, the headwind serves to help push the wake away from the arrival path, somewhat mitigating its effects.

 

Just like our recat here in the States, it's an acknowledgement that wakes were previously not fully understood and we can reclaim airspace we'd once protected for fear of coming into contact with wake turbulence. That fear was unfounded.

I thought that the whole idea behind NEXTGEN and probably SESAR in the EU is to automate these kinds of tasks and relieve ATC of workload. Is this an early implementation of these systems? At what point will ATC at Heathrow implement this? It sounds like a test run although they have run it through thousands on simulations and it is suppose to maintain airspace safety and alleviate crowding. This almost sounds too good to be true.

 

NEXTGEN is supposed to be like AIS in the maritime environment. AIS and the rule changes that accompanied its implementation provides transponder services that indicate course, speed and distance to discreet identifiers giving everyone so equipped basic SA in crowed waterways. It has been required on commercial vessels for awhile now and is now available to all vessels. It also provides incursion warnings but is more like TCAS than any ATC routing tools.

 

 

I thought that the whole idea behind NEXTGEN and probably SESAR in the EU is to automate these kinds of tasks and relieve ATC of workload. Is this an early implementation of these systems? At what point will ATC at Heathrow implement this? It sounds like a test run although they have run it through thousands on simulations and it is suppose to maintain airspace safety and alleviate crowding. This almost sounds too good to be true.

 

It's meant to make the airspace more efficient for both sides. When I said burden I wasn't necessarily meaning that it was a specific personal task burden. There's automation in place to help controllers space arrivals. Our STARS facilities have a couple tools to assist in this task (j-rings, cones, and there are a few other tools as well, but I'm forgetting the names), and I'm sure UK controllers have their own tools to keep workload down on their side, too. I was simply meaning to say that it wasn't something that the pilots need to concern themselves with. After all, how often do you see pilots worrying about what radar separation is required in various environments?

They have to automate, the various rules for crossing, opposing or leading scenarios alone beg for mistakes. Do you know what the current status of NEXTGEN is? I am an admitted tech nut and this system is fascinating just from a technology standpoint. I'm wondering what the fallback is if there is a system problem. Something this mission critical is going to be triple/triple redundant, what we call five nines failure proof meaning 99.999% reliable. Last question, I do appreciate your time and input. How will NEXTGEN interface at the tower level, like runway and approach assignments? Will the tower grunts still control the beginning and end of flight and the system mediate route control at the Center level? Thanks for your input.

Do you know what the current status of NEXTGEN is?

 

Things are being rolled in gradually system by system, really. IAD and BWI just got a bunch of new STARs that are part of the OPD part of NextGen.

 

Potomac has some STARS (the radar console in this case) stuff in place, though it hasn't fully converted. I think Washington Center is now on ERAM fully by this point (previously HOST), which means they're also using ADS-B to supplement radar (so far, only ZLC, ZTL, ZJX and ZMA are the only ones left).

 

DataComm is in place at many facilities for pre-departure clearances and so on (IAD is making good use of it - LiveATC's coverage of their clearance frequency is rather boring now).

 

Heck, if you're into all of this, you'll probably enjoy the direct info (with pictures, charts and tables) more than me typing it:

https://www.faa.gov/nextgen/library/media/NextGen_Implementation_Plan_2014.pdf

(Note: you'll see TBFM pretty late in that document - it is not what LHR is doing with arrivals management...different issue with TBFM as it's delivering aircraft from ARTCC to TRACON, not to the runway like the LHR thing.)

Thanks Kyle

 

 

My guard is always up because in sim forums there are a lot of members who are vague on the details of their experience and like to throw their opinions into the mix as if they have experience that gives their opinions weight.

 

+1