View Full Version : LPL 09 departures / MAN conflict?
A number of the 09 departures have a restriction of 1NM or 580 feet whichever is earlier before turning on northerly or southerly headings.
Most commercial a/c will reach 580' very shortly after the runway end (and well before 1NM) so should turn immediately they reach 580'.
Unfortunately although our FMC has the 580' restriction included...it does not act on it and will only turn (so I am informed) at about 1,700' when 1 mile is achieved.
Just want to get to the bottom of this as have heard a few guys recently suggesting "let the FMC do its thing" without knowing the background to the restriction.
Clearly we are nowhere near the low level corridor (still 3nms inside the LPL) have heard a rumour it is related to avoiding MAN holds?
I know its a restriction and should not require explanation...but to nip this in the bud some inside info would be useful.
Thanks in advance
opnot
28th Sep 2010, 15:38
RMC
This restriction would not have any bearing on Manch ops, it may be a liverpool restriction to avoid built up areas for noise purposes, only a suggestion
LEGAL TENDER
28th Sep 2010, 17:54
FMC at 580' ?? I am guessing that's operating in LNAV/VNAV mode?
Could you select HDG mode to do the turn as required?
Or alternatively, steer control yoke left/right as required? ;)
The first thing I have to ask is which chart provider are you using and also who provides the databse for the FMS.
I ask that because as I am sure you are aware it is the AIP that is the definitive reference and if you look at the AIP you will find that:
Taking runway 09.
The turn must be made after the departure end of the runway.
After passing the end of the runway the turn is to be made "as soon as practicable" but not below 500ft AAL (581ft AMSL) and no later than 1 DME.
Define as soon as practicable. Open to interpretation. However, "not below 500ft AGL" and between DER and 1 DME are very clear.
It would be reasonable to define a fix at the 1 DME point and make a restriction of above 581ft at that point. An aircraft following that profile would comply fully with the SID.
Therefore I would say that if your colleagues are starting the turn at the 1 DME point and are more than 581ft at that point then they are in full complicance with the SID.
The confusion has probably arisen on your part because one has to refer to several parts of the AIP to get the correct answer and the wording used in the Noise abatement procedures (AD section of AIP) is not the same as that used on the SID plate and even the SID plate has two slightly different wordings on it when talking about the same departure.
Imagine how some person who's job it is to encode that into a database and a chart is going to cope.
DFC - Answer to your questions...the FMC is supplied by Smiths Industries....the chart supplier is Jeppesen.
The precise wording on the Jep chart is "At ILVR 1 DME or 580' if earlier"
The majority of our people adhere to this as -
-Until now we had no reason to suppose the AIP would say something different to the Jep
-We do not have access in the cockpit to AIPs
...if I am going to convince these guys to trust the FMC 1NM turn I could really do with the reference that states the AIP is the master document....any help you could give with that would be greatly appreciated.
Thanks again.
Unfortunately although our FMC has the 580' restriction included...it does not act on it and will only turn (so I am informed) at about 1,700' when 1 mile is achieved. - there would appear to be a coding error in your database which you need to report. 1D ILVR is in fact DER as near as damn it!
The AIP is ALWAYS the master document and there really is no need to 'prove it'. It is effectively the source of national regulations, and chart providers are mere repeaters of the information - however, I do not see any error in the Jepp here.
1D ILVR is in fact DER as near as damn it!
No it is not.
The DME antenna is located abeam the mid-point of the runway on the south side - see aerodrome chart. The DME is adjusted so that an aircraft will receive a 0nm indication at the threshold of the arriving runway.
Since the antenna is abeam the mid-point and there is no significant displacement of the thresholds the DME will read zero at the departure end of the runway also.
Therefore (not allowing for slant range error) a 1nm DME indication will happen 1nm after the DER.
In fact if you fly a circle round the DME antenna crossing both thresholds then the DME will always show zero.
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RMC,
The only reason why 580ft is mentioned is to stop people interpreting "As soon as practicable" to mean making a turn at 50ft AGL.
They want you to turn as soon as practical between the DER and 1 DME but they don't want you to do it below 500ft AAL (581 QNH). It is that simple.
Turn at an altitude is a pain to put in an FMC while still keeping the following track and being able to fly it in LNAV. (Turn at an altitude direct to a point is easy).
On the 09 Dep to POL (POL5V) you have turn at an altitude to fly a specified track to intercept another track to POL.
You need to look at the FMS database procedure but it is likely that you have the following;
1. Turn at an altitude - 580ft
2. Intercept 360 Track to a point (place to be 3000ft+)
3. Intercept 063 track to a point (place to be at 4000ft)
Please chack your database to confirm this.
If this is the case then in simple terms the FMS gets to 580ft (say at 0.1 DME) and now starts to intercept the 360 track but it knows that it is too early to turn so it delays the turn until the right time to make a smooth turn onto the 360 track inbound to the coded point for the altitude limit - and with an initial climb speed and a bit of headwind this probably happens at 1 DME.
Since I don't have you FMS I can only give the most likely case.
However, I hope you can see a problem with the above - with a very low speed and strong heradwind the turn could happen after 1 DME.
That is why I said coding a turn at 1DME above 580Ft is the safest option.
Finally there are plenty of times where the FMS will not perfectly fly the Noise abatement procedure - Naples being a good example of where this happens and where it will cost you in fines if you rely on the FMS.
If you are worried, use HDG and rotate the knob at 581ft (stick it in TRK) and then tell the FMS to intercept the POL inbound track before engaging LNAV. One does not need to be a slave to the magenta line!!
Arty-Ziff
29th Sep 2010, 21:40
Apart from all the techincal "flying a plane" stuff that's been mentioned, I wouldn't worry too much about Manchester holds or conflicting with anything inbound/outbound from Manchester. You'll only climb underneath the MIRSI hold (which is the only Manchester hold immediately affecting Liverpool departures), and underneath outbound traffic from Manchester. If Manch are on 05, then you'll be given a non standard departure going southbound (to keep you away from Manch arrivals), and a DESIG or POL departure will either involve you levelling at 4000ft to keep underneath the inbounds, or some fancy vectoring to get you above the holding traffic.
Sorry this doesn't give you an exact expaination of why the restriction exists! Maybe noise as someone has suggested.
No it is not - yes, my mistake, I can see the DME on the AIP page - the Jepp does not show the DME TX and since the ILS freqs were separate I assumed it was threshold..................
You can add the HON R/Y at MAN to the 'don't try it in LNAV' list.