I could not find anywhere the answer to this question, but I was just curious to know. When flying a SID/STAR with altitude and/or speed constraints, are they always followed or is it up the the descretion of ATC i.e. like only during certain times of the day. Thanks for any infoDave S

No, ATC can often modify your route, allow you some shortcuts, vector you for traffic, etc. There is nothing "fixed" or "permanent" in the ATC world. You as pilot have also right to ask for exceptions if say you don't like the weather in front and want to modify your route. Remember fundamental principle in ATC - SAFETY drives everything and may trump any rule.

Thanks a lot Michael, I was always wondering about this, especially the part about shortcutsDave S

Thanks a lot Michael, I was always wondering about this, especially the part about shortcutsDave S

In my experience as a GA ifr pilot I have never flown 1 star (vectors always apply-usually before even the first fix even if assigned) and have only done 1 Sid-in 20 years of flying. I'll be the first to admit it might be different with the airliners as I don't know their situation-but I never understand the sid/star mania at least in my realm of Ga ifr flying. By the way-don't trust flightaware-I always look at my flights after I land-the direct flights they show are usually right (which I get 99% of the time) but the routed flights seldom match. Why? because vectors usually/always are what are given-regardless of the routing shown. Sometimes that routing is given in the initial clearance (rarely) but hardly ever ends up being the exact one.Why would these routings even be given? If radar coverage goes out you have a route to follow. But it is everyone's best interest to get where you are going as quickly as possible...the last full route clearance I got recently was flying from Nashua, Nh (Boston/NY congested airspace) to Michigan. I got one of the most complicated full route clearances I've ever had when contacting clearance delivery (and didn't match my filed routing at all). Took a while to copy/read back and 20 minutes to program into the kln94 while my engines were burning valuable avgas.After taking off I flew to my first waypoint -the next controller I contacted asked if I wanted direct (they see the /g in your flightplan). I was surprised after getting the complicated clearance and my voice must of shown it. He said-we aim to get you where you are going as fast as possible....is that ok with you? It didnt' take me a second to stammer yes...

I had one of those complicated full route clearances once night flying from Richmond VA to Teterboro NJ (seemed to have about a dozen segments for a relatively short flight... lots of dog legs too) and in this case we ended up flying it as cleared.... there are so many factors that I don't see how one can generalize. True, we usually fly direct /G but look where I am based.As for STARs: My experience based on listening to approach talking to the turbojets (I am in a C414) is that they are almost always cleared for the arrival as published for the transitions and cleared to cross the approach gate at the published altitude. I refer to the approach gate as the fix that usually is about 40nm from the airport with a crossing altitude of 10,000-12,000 ft where the handoff from center to approach occurs. Once inside the approach gate, it depends greatly on the location and type (RNAV or not) arrival. Most times, the arrival route is followed by vectors when 10-20 nm from the airport unless it is a RNAV arrival in which case the route is flown all the way down the downwind as published (my experience is limited to US where very few arrivals connect to approaches).As for SIDs: The locations with RNAV DPs faithfully fly these most times, while on the other hand all departures at OHare are vectors. Go figure.

Thanks for those detailed responses guys. Ok with that said, is it safe to say that with the MD-11 for example, V/S mode rather than PROF would be used on descent?Thanks, Dave S

I had one of those complicated full route clearances once night flying from Richmond VA to Teterboro NJ (seemed to have about a dozen segments for a relatively short flight... lots of dog legs too) and in this case we ended up flying it as cleared.... there are so many factors that I don't see how one can generalize. True, we usually fly direct /G but look where I am based.As for STARs: My experience based on listening to approach talking to the turbojets (I am in a C414) is that they are almost always cleared for the arrival as published for the transitions and cleared to cross the approach gate at the published altitude. I refer to the approach gate as the fix that usually is about 40nm from the airport with a crossing altitude of 10,000-12,000 ft where the handoff from center to approach occurs. Once inside the approach gate, it depends greatly on the location and type (RNAV or not) arrival. Most times, the arrival route is followed by vectors when 10-20 nm from the airport unless it is a RNAV arrival in which case the route is flown all the way down the downwind as published (my experience is limited to US where very few arrivals connect to approaches).As for SIDs: The locations with RNAV DPs faithfully fly these most times, while on the other hand all departures at OHare are vectors. Go figure.

Of course one should not generalize-but I have flown/landed in all the continental states now GA ifr andI get direct 99% of the time. Only time I've flow airways is in the west where I needed the terrain clearance and I asked for them. If I get a full route clearance-it is usually only followed at most to the first fix and then I get vectored or direct-which is always annoying after spending much time punching the gps. Check flightaware.com n7345r history-lots of straight lines going back for years. A rare route like from Burke Lakefront is shown on flightaware-and never do it-shortly after takeoff are given a vector and then direct/vectors depending on where Detroit wants us to go.I am only speaking of course of my experience in Ga. On one of my flight boards it was also asked the other day how many people had ever got a real hold. Most had never had one (I haven't)-a few who frequent uncontrolled airports had had a handful but no more than that.

Of course one should not generalize-but I have flown/landed in all the continental states now GA ifr andI get direct 99% of the time. Only time I've flow airways is in the west where I needed the terrain clearance and I asked for them. If I get a full route clearance-it is usually only followed at most to the first fix and then I get vectored or direct-which is always annoying after spending much time punching the gps. I am only speaking of course of my experience in Ga. On one of my flight boards it was also asked the other day how many people had ever got a real hold. Most had never had one (I haven't)-a few who frequent uncontrolled airports had had a handful but no more than that.

I have been flying as a passenger since 1982 and FS pilot for seven years now. I have been flying out of the busiest airport in the world, KATL, and I live about 20 miles from the airport. The planes along time ago use to fly holding patterns in circles around the airport. Now they just arrive and head for what I call the landing corridor. I can tell, on a clear night when ATC just vectors the airplanes to line up for a landing. I have spotted in one air column 4 planes at different altitudes heading in every differrent direction. In the old days you could tell the little airway highways by how all the planes use to fly. Today looking up from the ground can scare the HELL out of you. You can only hope all the pilots see each other and ATC knows where each planes is located. Modern techniques, I guess.Carl Perry

Geofa, I agree that in GA the directs are common but the question is regarding the procedures in air carrier operations (I think). I haven't had an ATC requested hold in GA flying either.Dave: The MD11 works so well in PROF mode that if the constraints in the flightplan agree with those on the chart I recommend PROF, just as done real world. What will usually happen in an ATC environment depends on the arrival or departure. The TRUDO1 (FMS) arrival into KMKE is a very unique case where the charted path takes you from TRUDO at 9000 right down to any one of four initial approach fixes. A more general case is BDF5 (Bradford Five) at KORD where all arrivals from the SW are lined up in an inbound train on the BDRr062 crossing BENKY at 11000 unless they are stacking up in the four published holds. Just before BENKY, center will hand the arrival over to approach and after crossing BENKY they will get further instructions, usually a vector and a new altitude constraint. In this case the arrival transitions are flown as published but inside the approach gate is pretty much up to approach control. Flying the MD11 on the BDF5 star you would use PROF all the way to BENKY then use the FCP controls for HDG and SPD to follow ATC home.In a simulated environment without ATC, I recommend my SIDSTAR collection where for example at KORD I provide 11 different enumerations of BDF5 for routing all the way to the ILS (eg, BDF5.10 provides a route for the simulation that mimicks real world tracks to the ILS for RWY 10.Hope this helps.

Thanks Dan, I do have your SIDSTAR collection. I guess my curiousity about this began when I was flying the FQM1 arrival into KEWR. According to charts, it states to expect clearance to cross SWEET at 7,000. This fix if I remember is about 40nm from the IAF to 22L. I thought thought it was somewhat strange to be as low as 7,000 when your that far away from the approach.ThanksDaveS

It is strange, but it is due to the location where they get the arrivals coming in from that direction below the departures I think. I have run into very few procedures that have you that low that far out. Notice FLOSI does the same thing. Browsing the Hi Preferred Routes from FAA reveals that most callout PHILBO, which arrives from the S/SW and avoids this lengthy routing at low altitude.

The Northeast Corridor around CN, NY, NJ, has several low entry points going into destinations in that area. KLGA approaches from the NNE have that about 50 nm out. I suspect it is the higher congestion of the NYC area.

Thanks Dan, I do have your SIDSTAR collection. I guess my curiousity about this began when I was flying the FQM1 arrival into KEWR. According to charts, it states to expect clearance to cross SWEET at 7,000. This fix if I remember is about 40nm from the IAF to 22L. I thought thought it was somewhat strange to be as low as 7,000 when your that far away from the approach.ThanksDaveS

I could not find anywhere the answer to this question, but I was just curious to know. When flying a SID/STAR with altitude and/or speed constraints, are they always followed or is it up the the descretion of ATC i.e. like only during certain times of the day. Thanks for any infoDave S

As you probably know, the whole point of SIDs and STARs is so ATC have 'all their ducks in a row' with no aircraft in surprising locations. Additionally, the pilots know they are clear of terrain hazards etc when flying those kinds of procedures.But it is often the case that aircraft will only be halfway through such a procedure when they'll get told to proceed on their own without the need to stay on the SID or STAR, or given a vector to send them on their way more expediently, since SIDs and STARs are really all about getting something pointed in the rough direction it needs to be going at a safe height. If all that stuff is being met, and it's safe to let an aircraft set off on its route before reaching the end of a SID, ATC will happily let it go. The same is true of all other ATC stuff, especially speeds, you will often hear ATC telling aircraft flying well below 10,000 feet that there is no speed restriction.Having said that, one or two SIDs can be followed for reasons other than safe traffic separation or terrain clearance, in which case they would be likely to get flown all the way through. For example, some SIDs restrict stuff because of noise abatement regulations, which is why you'll often find they are more likely to be followed fully at night, when the noise regulations are generally a bit stricter at many airports. That's why you'll see aerodrome booklets with SIDs in them that often list a specific aircraft type for a particular SID, which is usually related to minimum climb performance, to put the thing well above or abeam of noise monitoring stations on departure.If you have a local airport, it would be worth getting hold of the Aerodrome Booklet for it. That's the book that the airport regularly issues which lists all the SIDs, STARs and other stuff related to operating from that particular place. The SID/STAR charts are in it of course, so you can photocopy them or remove the pages if you want them on your yoke in FS. You would find it interesting to compare aircraft you see in the skies around the airport with the routes in the book, and if you are remotely interested in that sort of thing, it makes an interesting thing to have.You can buy them here: http://www.afeonline.com/shop/product_info...roducts_id=2135That's not the only place that sells them of course, but it is one of them, you can often find old out of date ones cheap in airport shops too, as they are not much use to pilots when they've been updated, but still very handy for simmers.Al

At a busy airport like London Heathrow SID's are most definately adhered to. Noise abatement procedures there are RIGID!. STAR's lead up to stacks from which a/c are vectored for continuous descent. If traffic is light then yes a/c are vectored at ATC discretion. But ATC will always try for a continuous descent. It would be chaos if each and every a/c was vectored individually!! When one is handling a take off and landing at 70 second intervals each it's not difficult to imagine the amount of strawberry jam on the ground if SID's and STAR's were not used!!Vololiberista