As most NGX experts have learned, it was best to have the NGX descent speed to be .78/280 kts on the FMC Descent page.  I think ATC has most jet traffic descend at that speed until the transition to 250kts at 10,000ft.   I don't know the specific reason, or if it's only applicable to aircraft in the 737 class, but what would be a reasonable speed for the 777?  IIRC, the MD-11 had a descent policy speed, I think the default was 290kts, and whatever the mach cruise speed was at cruise until FL280 or whatever FL that mach changes to IAS. 

 

What do the pros use for a descent speed on the 777?   I've been using the mach cruise/280 kts, but it seems a little slow.   But I also remember seeing some STARs in the U.S. instructing traffic to be at 280kts or slower at the intermediate altitudes. 

 

 

I think ATC has most jet traffic descend at that speed until the transition to 250kts at 10,000ft.

 

Nope.  ATC doesn't care, honestly.  The only time you're going to get speed assignments like that is in busy periods, into busy metroplexes like New York.  Even then, you normally don't get assigned speeds until you hit the TRACON.  If you get them on the center level, they're Mach speeds earlier on at cruise.

 

Short story: ATC doesn't have jet traffic descend at speeds where they can avoid it (about 90% of the time)

 

 

 

I don't know the specific reason, or if it's only applicable to aircraft in the 737 class, but what would be a reasonable speed for the 777?

 

Sequencing/spacing, if anything, but remember when the 737 arrives versus when the 777 arrives:

-737s tend to do shorter hauls, departing and arriving in busy periods

-777 tend to do longer hauls, departing and arriving in off-times (as compared to the RJs and other short route flights)

 

 

 

But I also remember seeing some STARs in the U.S. instructing traffic to be at 280kts or slower at the intermediate altitudes.

 

This would be a case for entering the descent speed on the DESC page of the VNAV pages, but unless you really want to set it as a default for all flights, you can just enter it flight by flight whenever you're on a STAR like that.

London likes to put on speed when it's busy, but it'll either be a quite high speed such as 300 knots, or if they're holding nowadays they use a system with which they will slow inbounds down earlier (so they don't have to go intot he holds for as long) and then they will instruct 250 IAS during descent.

 

 

It's very company specific though what the ECON speed is, there is as far as I know no general rule.

It's company specific and Tracon specific as has been mentioned. Cost index, traffic conditions, Star/Approach constraints, and weather are some of the more influential variables.

 

George

It's not uncommon to hear Houston Center giving speed constraints to the river of inbounds below FL230. Not every day, just depends on how the flow is working.

Thanks for the replies.  PFPX has the 777 as having a M.84/320kt "descent profile", so I'll go with that.   Err, maybe what ever the last mach cruise speed/320kts would make more sense, with a 60 CI on my current flight that works out to be about M.82 on cruise.

 

Sequencing/spacing, if anything, but remember when the 737 arrives versus when the 777 arrives:

-737s tend to do shorter hauls, departing and arriving in busy periods

-777 tend to do longer hauls, departing and arriving in off-times (as compared to the RJs and other short route flights)

 

Great observation Kyle.  I think about the time of my flight a lot when I decide if I should follow a published STAR "to a T", or take some shortcuts or liberally apply more or less speed than normal during the approach.   I often pull up the flight record in Flightaware and find my answer there!  Heck, I have at times adjusted my flight path when I see AI traffic sharing my same route by flying an offset LNAV path to realistically add separation!

 

 

-777 tend to do longer hauls, departing and arriving in off-times (as compared to the RJs and other short route flights)

 

I don't think that is applicable for airports such as Dubai, Hong Kong, Frankfurt, Heathrow.... the list can go on and on...

 

 

I think about the time of my flight a lot when I decide if I should follow a published STAR "to a T", or take some shortcuts or liberally apply more or less speed than normal during the approach.

 

STARs - more recently, anyway - generally get followed through unless you have one of two situations:

1. It's busy and you need to be sequenced with another stream feeding the STAR
2. There's absolutely nobody around and the facility has combined sectors

Situation number 1 is the most effective and common types of sequencing, tactically.  Controllers know that speed restrictions, particularly in the descent, can be troublesome, and the adjustment is generally very slow (unless you've leveled off at an intermediate altitude - rare now with OPD STARs).

 

Situation number 2 is less frequent and depends on a number of factors.  The first of which is that the facility needs to be combined.  As an example, when arriving from the north east at IAD (how most trans-Atlantic flights arrive), you'd talk to 3 controllers: BINNS, MULRR, and then IADFx (where x is E, C, or W, depending on your runway assignment).  In the middle of the night, you'd talk to 1: BARIN (all of the sectors combine down into it when things are slow).  The reason I point this out is to give you insight into the side most pilots don't see.  When I control all of the airspace, I don't have to ask the next sector over if I can do something non-standard.

 

 

 

I often pull up the flight record in Flightaware and find my answer there!

 

Yep.  That or listen to LiveATC a little.  Pull up an archive of an overnight shift and you'll see what I'm talking about, above.

 

 

 

Heck, I have at times adjusted my flight path when I see AI traffic sharing my same route by flying an offset LNAV path to realistically add separation!

 

Most of the time, even en route, it's just a couple vectors.  I don't think a lot of the controllers out there know that it's so easy to offset a route in some planes.  If they need to set up a "blow by," they'll normally vector the overtaking aircraft on an angle, and once separation is ensured, they'll give them "direct [FIXAA], rest of route unchanged."  What you're doing isn't incorrect at all though.  Just not often seen.

 

 

 

I don't think that is applicable for airports such as Dubai, Hong Kong, Frankfurt, Heathrow.... the list can go on and on...

 

It wasn't meant to be all-encompassing, which is why I used "tend to."  Additionally, even at the European airports you mentioned, the US overnight flight arrival times are rather early in the morning.  By the time most of those heavies have landed, the intracontinental flights are just starting to depart for the day.