FMS Question

[Hades]

I'm ATC, and as you all know, we don't learn all we should about flying those big birds before we control them dots around.. . So here's the question : In your FMS, If I tell you to go Direct to a point, do you delete all the RNAV ponts between you and this point in the FMS?. . If yes, is it possible for you to easyly access what you've removed if the direct routing has to be altered?. . And at last, does the FMS manage the SLA restriction by itself, or is it a manual reduction of the speed?. .. .Thanks for the Info!. .. .::Hades..

[moleslayer]

Hades........ .. .Most FMS have a [DCT TO]push button, just fill in the waypoint name in the brackets, and away you go.If the point you require is already in the flight plan you are using, its usually possible to just push the button next to that point, and the result is the same.If you did delete all the waypoints in the flight plan up to the one you want (very slow), then they are all recoverable as described above.. .Speed limit points are often coded directly into the flight plan, usually where they form part of a SID or STAR, if not pilots can insert them manually.. .Basically the FMS is a highly versatile tool, anything that the database provider doesn't insert into a 'Company Flight Plan'- the pilot can put it in themselves.The only thing that pilots can't alter are 'Database Approaches'.

[roger]

ok then. .You're cleared direct to BIG on a BIG3B arrival, would you prefer FL 150 to be level abeam TIGER, or FL 150 to be level 25dme before Big? Is one easier than the other? Just an example, I'm sure you pilot types get the point...

[Sniff]

737 FMC - When told to go direct to, then depending upon the FMC itself once you have done the button pushing you are left with one of two things:. .</font><ul type="square">[*]<font size="2" face="Verdana, Arial, Helvetica">Line direct between your present position and the waypoint that you are navigating to. All altitude/speed constraints are dropped.</font></li>[*]<font size="2" face="Verdana, Arial, Helvetica">Line direct between your present position and the direct to, and 'abeam' positions for all of the points that you have bypassed. All altitude/speed constraints are still dropped <img border="0" title="" alt="[Confused]" src="confused.gif" /> . .</font></li>[/list]<font size="2" face="Verdana, Arial, Helvetica">As you can see we have both systems in use - With the first putting in abeam Tiger as 22d before BIG (with FL150), and the second just inserting the Tiger restriction back in. Just for your interest, all LHR BA 737's are the second type; most LGW BA 737's are the first. So Roger an either/or clearance would be nice!. .As for airbus, ummmmmmmmm. .. .See ya! Sniff <img border="0" title="" alt="[Smile]" src="smile.gif" />

[Recover]

Hades,. .. .Just to add a bit more to Moleslayer's message. . .. .As he said you can either type in a point to go direct to, or you can bring a waypoint on the legs page to the top of page 1 and this will then go direct to this point (I'm talking Boeing so maybe a 'Bus person will help if it's any different). With most aircraft, when a wpt is brought to 'the top' an 'abeams' option is given. If accepted this will then create wpts along your new direct route abeam the original wpts. So if your original route went a,b,c,d and you were cleared direct a to d then abeam b & c would appear on the straight line between a and d. Hope I heaven't caused confusion. So if one is cleared direct Timba and presses abeams then Bexil's abeam will remain on the route. Unfortunately they normally drop any restrictions, so the pilot would have to put back the FL150 restriction on the 'new' abeam Bexil wpt.. .. .It's not a difficult job to put back wpts. They can either be typed back to their original place or one can pop them in a 'fix' page. With this option they then appear on the map with a green circle round them. One can select abeam the fix and then put this position back into the legs page. It's more logical than it sounds.. .. .So, overall, no it's not difficult but it may take a few seconds sometimes to type in. Due allowance should be made when asking us to route back to original point <img border="0" title="" alt="[Wink]" src="wink.gif" /> . .. .As far as speeds are concerned the kit will do the speed reduction for you, so long as you're in VNAV (the 'Bus people prefer to be 'managed'). With this engaged the autopilot will fly the vertical profile you've 'attached' to the wpts, so long as ATC let you descend (or ascend). So if we were told to leave FL350 when ready and be at Bexil at 250 kts and FL150, so long as we were actually cleared to descend to FL150 or below then the machine will do it. If we were only cleared to FL200 then this would go into the mode control panel and the autopilot would level the aircraft at FL200. If it's taken out of VNAV, then pilot is basically doing it all him/herself.. .. .BA still run famil courses for ATC so try and get on a flight. All will be explained much more easily when you can see the kit in action <img border="0" title="" alt="[Razz]" src="tongue.gif" /> . .. .And...... .. .Recover

[romeowiz]

May I ask you a question concerning FMS: we had an incident because a pilot was cleared direct to COA and typed COSTA into the FMS. This is an intersection near Valencia, Spain. The same thing once happened with MTR, Metro. Any trouble of this kind happened to one of you?? There are quite a few five-letter VORīs that could be mixed up with waypoints??

[Pontius]

It's hasn'thappened to me (yet), but I could certainly see why it could happen very easily. There is, however, a very easy way of getting round the problem. When an alteration is made on the legs page, the new route is shown on the map with a dashed white line. It really is a simple matter of checking the modification makes sense before executing the change.. .. .I realise it might sound holier-than-thou, but I make sure I do this every time and I know certain airlines insist on a cross-check before any changes are made.. .. .The AA 757 in Cali could have have made their lives alot easier (and longer) if they'd had a look at their map before pressing 'go'. I'm not slamming the guys, but I've learnt a lot from their mistakes.. .. .So if COSTA disappears off the map at 90 degrees and the legs page shows a few hundred miles away, then it is a safe bet you've done something wrong and it's either time to get out the chart or ask the friendly person on the ground.

[tired]

On the original question.... .A340 - we also get the option to put in the abeam points when cleared direct or not, it's our choice. Personally I always select the "with abeam points" option for just the reason you're asking about - I can then put in a speed/altitude constraint if you give it to me. So I would prefer you to give me the constraint as "abeam Tiger" rather than "25 before BIG". However, lots of my colleagues don't use "abeams", so I guess it's a moot point.. .. .The point raised by Vector Pushtin..... Pontius is correct, it's up to us pilots to make sure that the new routing makes sense - the trainers in my mob are quite hot on drilling that into us (anyway, it's basic good airmanship.) Unfortunately, mistakes do happen.... However, there's another aspect to using a VOR's name, rather than it's identifier, on the RT - different pronunciations of the same name by different nationalities. After 15 years of flying through French airpsace I still do not recognise the way a French controller pronounces "Agen" - it's totally different to the way I pronounce it!! (Yes, yes, yes, I know his is the correct way, I'm just an ignorant Englishman <img border="0" title="" alt="[Smile]" src="smile.gif" /> ). If he just cleared me to "AGN" it would help me tremendously. On the same topic, how many Yanks call STU "St Rumble"?! I know it's ICAO procedure to use the name, rather than the identifier, but that's one procedure I think should be amended.

[ERJ_145]

I agree, one of the most tiresome tasks I do is sit down with a chart and convert 3 letter VOR names into "Biggin Hill" etc. ICAO should change to make it standard to refer to it as BIG not Biggin Hill, and remove room for error!

[Hades]

Thanks for all that info!!. .. .About those "observer flights" as they're called around here, tey've all been cancelled, until further advise, due to Sept11. Guess I'll have to wait some time... .. .For them waypoints... easyest and most comprehensive methode, if you ask me is "Cleared to Dijon, DJL". Takes 2 seconds, never a "Say again".. everybody happy.. .. .It's quite difficult what that FMS is able to do, even though we had a quite complete theory about it, but your feedback helps a lot. . .. .::Hades..

[romeowiz]

@MANAGP: thatīs a Human Factor item. I told my fellow controllers a lot about it, but one is easily trapped by this kind of error. Take DKB for an example, Dinkelsbuehl. Sounds very cosy, familiar and warm for a German, like a grandmother talking friendly to her little grandson, but is almost impossible to pronounce for the rest of the world. (probably the same happens with "AGEN" to the frogs!) So we take the option and name it AND spell it. But what for all the new bull****points with five letters? Takes a lot of time.. .. .For the original question: if you can easily fly with restrictions given for a "abeam" position, what would you expect me to say if I have a change. Letīs imagine a clearance like "descend FL240 be level abeam TIGER". If I then clear you further down but still want you to cross abeam TIGER at 240, is it OK to say "continue descent FL200 maintain programmed profile" or something, or just say "cross abeam TIGER FL240 or below"?

[Sniff]

Hades - In the BA Jump seat policy (the one that got revised post 11/9) ATC and ATC students are welcome! (I admit administration may be a different matter). .. .Vector-pushin - Use the old stuff - If you tell us to 'maintain programmed profile', you will find that when we get to Tiger, we will stop descent (as that is when the profile does until it needs to descend again for the next restriction or even the runway!) and not maintain the 500'/min descent as required by the ANO.

[Smudge's Lot]

What is slightly confusing (with regard to Direct to and Height constraints on STARS) is when we are given a height restriction which is specified as 'xx' miles before a main VOR. One example is the lorel arrivals for LTN and BHX when, I believe, it is common for "Descend FLxxx 20 miles before MID. Fine-the only problem for the FMC is that the point AVANT is 18 miles before MID and if you try to construct a waypoint as MID/-20 then you get an error msg so you have to build one as AVANT/-2 (ie 20 miles bfore MID). This can complicate the descent slightly at a time when changes to the FMC are supposed to be kept to a minimum (Company requirement) . . I suppose what I am trying to say if that is what you want, the say descend FLxxx by xxx waypoint and NOT expressed as a mileage before another waypoint.

[Pegasus77]

Pontius: Checking what you are entering before executing is a Boeing-thing only. Sorry to say that if you press DIRECT TO, an Airbus immediately flies in the new direction, and then you see the new green line on your NAV-display.. .There is more room for error there I believe.. .IMHO this is one of the very few real designflaws in the Airbus-logic.

[Hades]

@Smudge's Lot : How about the restriction "In xx NM from present position" ? Does the FMS have an easy input for that one?. .. .CHeers. .. .::Hades..

[Smudge's Lot]

No, if you say xx miles from present position, it would be almost impossible as the FMC is moving as fast as the a/c ie 7 miles a minute. The easist way for 'non-standard' descents for all pilots is for the height constraints to be fully published in the AIP and all Jepp/Aerad charts. I understand that at the moment, there are several dozen such restraints known by 99% of all pilots and by ATC but are NOT officially published-WHY NOT? <img border="0" title="" alt="[Eek!]" src="eek.gif" />

[romeowiz]

To eliminate Human Error; once you have common practice published one tilts towards complacency!. .Once in a while there will be an exception to the "rule" of having to cross XYZ at FL250 because of traffic underneath. You will be assigned FL260 but thereīs 250 in your software, thatīs a trap.

[Smudge's Lot]

Vector-As much as a trap as not knowing the 'Standard' descent levels, assuming an optimum descent path(ie no early levels) and then finding that you are far too high and cannot comply with the early descent restriction.. . When I said publish the early descent profiles, I do not mean incorporate into the FMS software as a Hard Instruction, just publish it so that those levels can be seen on the relevant Jeppesen/Aerad charts that most pilots use! <img border="0" title="" alt="[Smile]" src="smile.gif" />

[romeowiz]

OK, most of these restrictions are defined in LoAīs between ATC-Units and do not find their way into pilots publications. We alter our procedures a lot referring to traffic amount and day7 night or weekends, thatīs a good reason, too - not to publish. . . If we would know your descent profile we could find a good compromise.. .If you fly an airliner into STR e.g. I could give you some hints.

[tired]

You know, at the end of the day, we (pilots) should not need to have to rely on the FMS to get these levels right. I've found over the years that 1000' every 3 miles works well in all the jets I've flown - if ATC gives you an unexpected descent, it doesn't take too much mental agility to work what distance you need to lose the height (always remembering the wind factor, of course <img border="0" title="" alt="[Wink]" src="wink.gif" /> ). I'm not the brightest light in the harbour and I generally manage to get it right (more or less ), so you youngsters shouldn't have any difficulty at all.. .. .(Edited for etrocus spelling and general ham-fistedness.). . . . <small>[ 19 March 2002, 22:37: Message edited by: tired ]</small>