Sign in to follow this  
brucek

Few Airline 'world' Questions

Recommended Posts

I have a few questions I hope someone could help me answer...Question 1: In real life, do airline pilots have to "wait" until ATC advises them they may start their descent according to theflight plan given to them by each airline...or do pilots descend automatically according to the FMC? Question 2: Often, airline pilots set a probable landing runway for their arriving airport on the FMC before departure...How do they know they will probably land on the particular runway?thanks,b. glass

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

1) At Heathrow (EGLL) and Gatwick (EGKK) the STARS have a note saying "DESCENT PLANNING Pilots should plan for possible descent clearance as detailed in the table below. ACTUAL DESCENT CLEARANCE WILL BE AS INSTRUCTED BY ATC".2) Again, at these two airports STARS terminate at holding fixes that serve all runways. Aircraft are normally under Radar Control from the holding fixes to the Final Approach Track. During this period "changes of heading or flight level/altitude will be made only on instructions from the Radar Controller...".I hope this helps.

Share this post


Link to post
Share on other sites

1) If ATC coverage is available ATC has authority over altitude and flight profile (barring emergencies).2) weather forecasts and knowledge about normal conditions at the arrival airport (for example, Curacao will have arrivals on the 11 over 95% of the time, Schiphol has published runway utilisation schedules which are diverted from only when the wind is extreme and makes the default runway choice impossible).

Share this post


Link to post
Share on other sites

1. That is not an airline "world" issue. When you fly under IFR, your altitude is controlled by ATC. This applies whether you are a Flight 1 Warrior or a PMDG 737NG flying IFR. The MSFS ATC will descend you when you are at a point that is calculated to be a 3 degree descent to your destination. If you have other earlier altitude restrictions programmed into your FMC per your arrival plate, then of course, you will get your VNAV descent guidance prior to the MSFS ATC giving you descent instructions. If that is the case, either ignore your altitude restrictions since the MSFS ATC does not know or care, or you can hit the ATC menu and ask for a lower altitude.2. Check the weather at your destination and you can take an educated guess at which runway to enter. Or you can just leave it and wait until you are closer to the destination and have received the ATIS. It doesn't really matter unless the arrival procedure contains differences.

Share this post


Link to post
Share on other sites

1. In real life it depends entirely on the class of airspace. Many people think IFR means that you are controlled. This is not true. If your are in Class A-E IFR you are controlled. If you are in class B-C when VFR you are controlled. In Class D and E airspace, if the IFR flight is in VMC (Visual Meterological Conditions) then the pilot may be asked to resume own navigation and maintain own seperation with possibly a minimum/maximum alt clearance. This effectively means the PiC can choose a level. If IFR and in IMC (Instrument Meteorological Conditions) then the level will be controlled by the controller. This could be "Descend FL60" "Descend to FL60 10 miles before CPT". The latter requiring that the PiC (or the FMS!) calculate the vertical speed needed to arrive at FL60 at 10 miles DME from CPT (e.g. not 9 or 11).Now, the FMS (or FMC - whichever you prefer) has a VNAV option that most operators stipulate is bad practice. Simply because there is less control. Most Operational Procedure Manuals will specify the vertical navigation is handled manually via the autopilot control panel.2. They don't. They might guess that a certain runway is available, but they don't depart on the strength of that alone. However, IFR commercial flight planning is done assuming the most limiting of either a still wind or forecast wind (worst performance case) at the destination and alternate aerodromes taking into account all non-length limiting runways available for use with an hour of the ETA. Therefore, no assumptions are made that can, within the bounds of the available data, limit the aircrafts options for a suitable landing location.

Share this post


Link to post
Share on other sites

>In Class D>and E airspace, if the IFR flight is in VMC (Visual>Meterological Conditions) then the pilot may be asked to>resume own navigation and maintain own seperation with>possibly a minimum/maximum alt clearance. This effectively>means the PiC can choose a level. If IFR and in IMC>(Instrument Meteorological Conditions) then the level will be>controlled by the controller. What part of the world are you flying? Flying around the US, Mexico and Canada, I've never heard or experienced such a thing. When did weather being IMC or VMC mattered to an IFR altitude assignment? When you are IFR, you're IFR, ATC here does not change the separation standards, asides from clearing you for a visual approach or letting you reference some traffic so you can get on with a climb or descent. If you are somehow thinking of block, cruise, or discretion type altitude assignments, those are still assigned by ATC. Your ability to choose is defined within that criteria. It is not purely up to you, you are still under their control, albeit with a little wider margin than just one altitude. "Resume own navigation", as a term has nothing to do with altitude. It means to join some segment of your route and do your own navigating at the end of a vectoring sequence. The only place where IFR flights can be conducted outside of ATC control is in uncontrolled airspace. Hence the term uncontrolled. D and E are controlled airspace.>This could be "Descend FL60">"Descend to FL60 10 miles before CPT". The latter requiring>that the PiC (or the FMS!) calculate the vertical speed needed>to arrive at FL60 at 10 miles DME from CPT (e.g. not 9 or>11).>By your "FL60", I'm guessing you're talking about Europe. I'm glad they're not like that here on this side of the Atlantic. We'd have so many people get busted if ATC wanted that sort of stuff all the time. All the crossing restrictions we ever get are to just cross a fix at a certain altitude, you are free to get there earlier, no need to hit it right on except for your own ego.>Now, the FMS (or FMC - whichever you prefer) has a VNAV option>that most operators stipulate is bad practice. Simply because>there is less control. Most Operational Procedure Manuals will>specify the vertical navigation is handled manually via the>autopilot control panel.>Who is "most"? The airline I work for wants us to utilize those vnav needles more, with gas prices being the way it is. In fact, they even talk about making 4 degree our standard descent, to more closely resemble an idle descent. I hope not, since that will blow my "rule of 3" and "rule of 5" crutches out the window. Not to mention leave us jacked up if they want us to both slow down and go down.>2. They don't. They might guess that a certain runway is>available, but they don't depart on the strength of that>alone. However, IFR commercial flight planning is done>assuming the most limiting of either a still wind or forecast>wind (worst performance case) at the destination and alternate>aerodromes taking into account all non-length limiting runways>available for use with an hour of the ETA. Therefore, no>assumptions are made that can, within the bounds of the>available data, limit the aircrafts options for a suitable>landing location.How can you say that we don't? This kind of stuff is personal preference. Personally, I don't usually bother programming it in that early, unless there was a good reason. I have flown with people who religiously entered an arrival runway while we were still sitting at the gate. Sometimes you have to, because the arrival procedure at the destination diverges for different runways, so our Honeywell brand FMS will not even show the STARs unless a runway is entered. Entering a runway also can skew the estimated arrival times for our ACARs purposes and we would end up getting there earlier than they expected. I personally would rather be fashionably late than to sit there short of the gate waiting for the rampers to run out to meet me. Again, though, what you do here is personal in nature.Anyways, I don't mean to sound mean, but I think your post just did more to confuse the poor newbie trying to get a handle on whether to let that PMDG plane descend on it's own or wait for the MSFS ATC to tell him to descend than anything else. As a flight instructor, I could have spouted all I wanted to about airspace and buffet margins and stability and coffin corners to my students on their first lesson and sound real smart, but it would have done not a bit of good since it would be places and things that they were just not ready to go to yet.

Share this post


Link to post
Share on other sites

>Anyways, I don't mean to sound mean, but I think your post>just did more to confuse the poor newbie trying to get a>handle on whether to let that PMDG plane descend on it's own>or wait for the MSFS ATC to tell him to descend than anything>else. Sorry, so much info was given to me...so do real world airline pilots let the FMC descend the plane automatically, or do they wait for ATC descent clearance?? (basically it's one or the other)thanks,b. glass :-)

Share this post


Link to post
Share on other sites

Perhaps you'll find this link to the AIM section on STARs helpful:http://www.faa.gov/atpubs/AIM/Chap5/aim0504.html#5-4-1Any crossing altitudes and speeds depicted on a STAR are for planning purposes, unless the controller clears you with something like "BarnBurner 123, when able, proceed direct Panoche, descend via the Panoche 2 arrival."John

Share this post


Link to post
Share on other sites

He did ask about real life, not PDMG!You misread the Resume Navigation bit. Either that or I mis-wrote. Either way I agree. Regardling the FL60 bit. My mate said recently the most difficult thing about operating the 737-200 (no FMS) was nailing the descent rates.I said it before, I'll say it again. I will always defer to active commercial pilot knowledge. I am still in flying training. Therefore, I know this is like telling you to suck eggs, but humour me as I'm in a typing mood: I assure you, according to both JAA and generally ICAO, you have more options when IFR in VMC with regard to approaches and seperation. Also, the responsibiliy for seperation from terrain and other aircraft can shift to the pilot when VMC, even when IFR. With regard to the letter of the law IFR changes the way you calculate MSA. It doesn't actually mean you need to fly by sole reference to the instruments - that is what IMC means and that is why there is a seperate column in your logbook. IFR does also change the contract between the commander and ATC depending on the Class of airspace. Saying that, ATC always has responsibly for seperation when vectoring. In fact, in JAA land, you don't need an Instrument Rating to fly IFR. If you have a vannila PPL, then so long as you are in and will remain VMC, you can file IFR!Be as mean as you like, but you are probably right...SORRY FOR ANY CONFUSION :)

Share this post


Link to post
Share on other sites

I am glad you did not take my comments the wrong way. Congratulations on deciding to learn to fly. You seem very learned with book knowledge. The only thing is I kind of sensed, while reading that post, is that there was a whole lot of stuff you've read in books, thought that maybe you understood, but did not have much actual real life experience with. Nothing in your post is entirely incorrect, even the part about airplanes in VMC being required to maintain their own separation for example, which is a true statement even here in the US, as any aircraft is ultimately responsible for its own separation when meteorological conditions allow. Sure. However, the context with which you used those statements gave a very confusing and very incorrect picture. Come back in a few years, and after you've got a few hundred hours under your belt, and reread what you wrote and I bet you would also cringe when you read that post.

Share this post


Link to post
Share on other sites

Yes, this thread has now missed the point further than a than a Blackbird pilot unsure of his position! However......I already have a coupla hundred hours and a UK instrument rating, so although nowhere near your experience I do have an inkling :)Not that I wish to argue, but we have lots of Class D and E airspace here (UK), so the IFR and VMC issue is an important one. The whole thing has become confused by the challenging of facts and the resulting 'clarification'. My original point is that deciding on a runway at departure is not just a case of guessing, but is constrained by a few factors.

Share this post


Link to post
Share on other sites

Hi,I think most has been already said here, but let me add on how it's done here in the US. (I fly instrument, and while it's not a jet, I still receice the same ATC advisories as the airliners do).Your FMC creates a Top of Descent point, as you know. In the absence of any ATC restrictions, that is the most economical point for the aircraft to begin descent. ATC controllers know that airliners have this equipment, so will often say "Descend at Pilot's Discretion". As long as this is said prior to reaching the TOD point, the pilot can continue on the FMC descent from the TOD point and basically just let the FMC control the entire desent (if no further restrictions are made by ATC). The pilot must tell ATC that they are vacating their altitude (one of the compulsory communications required when IFR).If ATC issues a hard descent request prior to or after the TOD point, then unless the FMC can regain the planned descent path, you will be using FLCH or V/S to do your own descent (and this is the most common).Someone mentioned STAR's. Just being cleared to fly a STAR does not infer any permission to descend via the altitude contraints, but only to fly the lateral part of the STAR. What you need to hear is "descend via the xyz STAR', the you can use the hard altitude points in the FMC to descend via the STAR altitudes.You also asked about runway assignments. Say you are at FL350. Your first desent clearance may be to FL210 or something like that, which is in the overlap between the high altitude and low altitude sectors. Since the STAR is always in the low altitude sector, at some point during your descent in the high altitude sector, prior to FL210 (in my example), you will be told to "expect the xyz STAR".Accordingly, once you are accepted by the low altitude sector controller, you will be told to "expect runway ab". This gives you lots of time to brief the approach, etc. The actual runway assignment (versus the "expect runway assignment") is given by Approach Control, but you really need to know the runway assignment long before getting into the terminal environment.I hope this helps. It's often hard to know how it's actually done, even when you have the opportunity to listen to ATC regularly, unless you're actually doing it, and understand the control structure.Of course, countries and even locations within the US may vary. Controllers are all people and are very different to work with. After a while, you actually start being able to predict what an actual voice will say, and how they will control you. Scary, huh? :)Bruce.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this