question about times

[darry2385]

I was at the observation area last night killing a little time before I had to pick the g/f up from work and tower was talking to JetLink 4900 about having problems w/ their edict and release times.  My best effort at transcribing from the feed archive...

Tower: JetLink4900, we got and edict program for Newark, they moved that time up. then we got a call for a release time for flow, then they gave us a wheels-up time of 00:31, that's 1 hour 17 from now.

The feed didn't get the audio from 4900, but I remember him "complaining" about how they had just de-iced and will have to go do that again before they can leave. 

Tower: Yeah, I know what you mean, this is an ongoing thing w/ Newark and Flow, I don't understand how it works.  They call and give you one time then they call and give you an hour delay.  It makes no sense at all.

some time passes...

Tower: THey have two programs every day in Newark.  They have an edict program, which your time is 23:12.  Then we have to call flow so we can fit you into the sequence and for whatever reason, Newark is always...they give you times that are off the wall.  You know, we call for O'Hare and they have an edict and add or subtract 5 minutes, but its reasonable.  Here, you got 23:12 and then 00:31.  How can you plan on that, especially in the winter.  You can call company, maybe they can swap you with someone down the line here, but...

this got a little discussion going on among 4900, another flight at the gate I can't remember, JBU11 and tower.  It ended w/ JBU asking for their wheels up time, which was too far in advance to be in the system, to which JBU replies "yeah, we're overachievers"

Around 23:30, 4900 got cleared to leave and all was well. 

But my question(s) is/are what exactly is an edict time.  I'm assuming release time is the time flights are allowed to take-off, is that correct? 

[KSYR-pjr]

EDCT - Estimated/Expected Departure Clearance Time

In general, ATC prefers to keep aircraft on the ground awaiting departure rather than allow them to depart only to have too many in holding patterns awaiting sequencing.  Aircraft flying to the big-three NY airports are continually subjected to EDCTs.

[jmcmanna]

EDCT times are generally national ground delay programs designed to ensure arriving aircraft meet a specific arrival rate into an airport (in other words, so many aircraft per hour).  ATC usually finds out the EDCT time the same time as they receive the aircraft's clearance, and they are relayed to the flight crew.  The issue comes when they amend the EDCT programs when the aircraft is pushing back (or the destination airport goes into a ground stop, making all the EDCT times void and new EDCT times are issued).

A center flow release comes from the overlying ARTCC and are usually only required for aircraft going to busy airports, and sometimes only certain times of the day.  This is to ensure that aircraft bound for certain airports meet prescribed in-trail requirements with the neighboring ARTCC.  They call them ESPs (Enroute Sequencing Program), DSPs (Departure Sequencing Program) or CFRs (Call for Release), depending on the ARTCC, but they all work about the same way.  The tower calls the center for a release time, Center gives a release and void time, and the tower ensures the aircraft departs within that window

EDCT and ESP programs are separate, but sometimes overlap.  Example 1: EDCTs to LAX.  N12345 has an EDCT of 1653.  There is no requirement for the tower to obtain a center release for LAX departures from this airport.  The tower ensures that N12345 departs within 5 minutes of 1653.

Example 2: EDCTs to JFK.  N12345 has an EDCT of 1653.  The departure airport is required to ESP all departures to JFK.  Tower calls for N12345's release, and they say "released at 1657 void at 1659".  Tower ensures N12345 departs between 1657 and 1659. 

Sometimes the flow release might be way past the EDCT, and it does happen once in a while.  The Center flow release has the higher authority.  The EDCTs give a 10 minute window per aircraft and usually are issued well ahead of the aircraft's departure time.  The ESP/DSP/CFR releases are based on up-to-the-minute traffic restrictions and much more precise for fitting aircraft into the flow.

[aevins]

EDCT - Estimated/Expected Departure Clearance Time

"Expect" (Estimated on ETMS) departure clearance time - a fact that for some reason has always bugged me (not being picky just venting  )

[mklatval]

Yeah and you can ad CDT to that list (It's like DSP but a 1 min window instead of 3) I feel like a large part of my job is schmoozing TMU for good times. Usually if the place has already de-iced and you  let TMU know they will give you a better time. Also if you know the aircraft's edct you can call a half hour ahead to get a DSP to match and then you'll have better luck.

[jmcmanna]

Yeah, I hear ya on the schmoozing thing.  Usually the "they're de-icing" thing works pretty well for us, too.  Calling 30 mins ahead usually does not work here though . . . they'll just say "looks good, call when he's taxiing out" then give a 45 minute delay when I call back.

We're on the boundary with ZMP and ZAU, so 1/2 of NWA departures go through ZAU TMU (for DTW) and 1/2 get ZMP TMU for MSP.  Last week a guy called ZMP TMU by mistake and got a release for a Detroit flight (ZMP just said "released" without checking the flight number).  15 minutes after takeoff, ZAU TMU called up, pretty pissed, "what time did you get for NWAXXXX for Detroit?!?"  Whoops.