CLN2E out of EGSS incorrect speed restrictions

[Berzerker]

The CLN2E (Clacton 2E) departure out of London Stansted (EGSS) appears to restrict all waypoints until SSE26 to 250kt, but the restriction is only assigned until SSE11. There’s a notation on the chart if “After SSE11 MAX 250KT below FL100 unless otherwise authorized”

I understand the altitude restrictions after that are under FL100, but when given an instruction of “climb now” out of essex radar, you would not be restricted to those altitudes after SSE11 and above FL100, you should be able to speed up past 250KT. However, due to the speed restrictions in the navdata, after SSE11, a VNAV profile will keep the A/C at 250kt

[NAVData]

Hi,
sorry, due the lack of information only a general answer. I don’t understand what is/should be incorrect now? How should this coded in your eyes?

You see on the charts (Jeppesen and AIP UK), this limitation after SSE11 below FL100 unless otherwise authorized.

When you now cleared higher as the FL100, than you can increase the speed after crossing FL100. Sorry, possible I missunderstood you here, but I can’t see what should be wrong in the coding/on the charts. You must always code the minimas of what is allowed not the maxima what is possible.

Last, remove the restrictions in the FMC and the VNAV profile should be ok again, but what should the aircraft do, when it doesn’t get the higher cleareance? Yes, it must hold the speed and thats the minimum requirement …

Cheers
Richard

[Berzerker]

sorry, due the lack of information only a general answer. I don’t understand what is/should be incorrect now? How should this coded in your eyes?

The 250kt speed restrictions should simply be removed for all points after SSE11. They only apply under FL100, which is noted on the chart separately.

You see on the charts (Jeppesen and AIP UK), this limitation after SSE11 below FL100 unless otherwise authorized.

Correct, this is for situations in which you are allowed to climb past FL100 before the end of the SID (i.e. “climb now FL180” given from essex radar)

Sorry, possible I missunderstood you here, but I can’t see what should be wrong in the coding/on the charts. You must always code the minimas of what is allowed not the maxima what is possible.

The point is not coding anything. There’s no speed restriction after SSE11 for any lateral navigation point as noted on the chart (separately from the overall restriction of 250 below 10000), yet each way point is coded to restrict to 250 in the navdata itself. Per the chart, you are allowed free speed, after SSE11, so above FL100 you should still not be restricted to 250kt.

Last, remove the restrictions in the FMC and the VNAV profile should be ok again, but what should the aircraft do, when it doesn’t get the higher cleareance? Yes, it must hold the speed and thats the minimum requirement …

Yes, this is possible, but not all addons allow this functionality, so it should be programmed as it’s denoted on the chart initially.

[NAVData]

Hi again,
sorry, still can´t see why this should be incorrect. Without any ATC, the whole procedure are completely under FL100. When you look on the chart, you see on EVERY waypoint in the sequence a hard altitude restriction, that means without any ATC clearance you must follow this profile.

I have also looked into the AIP UK and here you find following note at EGSS:

So my understand for that is, the speed restriction is mandatory till you get the “no ATC speed restriction” command by the ATC. But that clearance is explicit, depending on the situation and not per default. According the charts, without any ATC order you must fly 250kts because all waypoints are below FL100.

Cheers,
Richard

[Berzerker]

Without any ATC, the whole procedure are completely under FL100. When you look on the chart, you see on EVERY waypoint in the sequence a hard altitude restriction, that means without any ATC clearance you must follow this profile.

That’s correct, so you shouldn’t even need a hard code of 250kt at those points for that reason. The charts also agree since there’s only a MAX 250 listed at SSE11 and nothing afterwards.

So my understand for that is, the speed restriction is mandatory till you get the “no ATC speed restriction” command by the ATC. But that clearance is explicit, depending on the situation and not per default. According the charts, without any ATC order you must fly 250kts because all waypoints are below FL100.

Again, I’m talking about if you’re given clearance to climb past FL100 by ATC (which is common at times when there’s not much traffic), you would be way above FL100 even before SSE23 or 18, but the restriction is only for below FL100. In these cases (again, when you’re above FL100), you should be able to speed up past 250kt once you reach FL100. I understand you can delete the restrictions, but the restrictions aren’t there on the chart and they shouldn’t be hard coded in.

[NAVData]

Again, you can´t expect such a clearance. The default (and that´s what is coded) is keep 250kts below FL100 and the reason why this is coded in this way is, because it is EXPLICIT mentioned because at least in Europe you may general fly not faster than 250kts below FL100.

When you get the clearance, delete the speed-restriction and you can fly the cleared speed …

By the way:
According the rules, when a speed restriction is set in a sequence, you must hold it till either a new restriction is set, ATC cleared you to speed up or slow down or you´re reaching FL100 (again at least in Europe). In other words - also, when this 250kts are not coded, you must hold this 250kts … and when you cleared for “no ATC speed restriction” you can set the speed you like.

Cheers,
Richard

[Berzerker]

Again, you can´t expect such a clearance. The default (and that´s what is coded) is keep 250kts below FL100 and the reason why this is coded in this way is, because it is EXPLICIT mentioned because at least in Europe you may general fly not faster than 250kts below FL100.

And again, I’m not, but even if I don’t get the clearance, I’m restricted below FL100, so I’m at 250KT Max anyway. There’s no need to hard code it. But if I do, then I am, according to the charts, allowed to fly faster than 250kt when I’m above FL100 (as long as I’m past SSE11). That is objective according to the charts. Navigraph’s navdata is assuming an incorrect restriction when it may or may not apply in all situations.

When you get the clearance, delete the speed-restriction and you can fly the cleared speed …

Yes, but this is a workaround for incorrectly coded navdata. And, again, not all planes have this capability depending on how deep their system development is.

According the rules, when a speed restriction is set in a sequence, you must hold it till either a new restriction is set, ATC cleared you to speed up or slow down or you´re reaching FL100 (again at least in Europe). In other words - also, when this 250kts are not coded, you must hold this 250kts … and when you cleared for “no ATC speed restriction” you can set the speed you like.

This is only applicable for if ATC sets you the speed restriction, not the chart. The chart’s speed restriction are based on lateral path. Once you pass a point that’s labeled “MAX 210KT” and there’s no restriction later, you may speed up to best practical forward taking into account any implicit or other restrictions set (i.e. 250 under 10000).

I’d appreciate it if you got a second opinion internally. I’ve talked to multiple real-world pilots about this as well and they agree with me.

[NAVData]

Allright, we will discuss this internally.

Cheers
Richard

[Rodeo314]

I think the confusion here is, in the UK, the 250/FL100 limit does not apply unconditionally (unlike e.g. in the US).

US regulations:

§ 91.117 Aircraft speed.

(a) Unless otherwise authorized by the Administrator, no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 m.p.h.).

UK regulations:

Airspace Speed Limit (SERA.6001)

Aircraft flying below FL100 are required to observe, with exceptions, a speed limit of 250 kt IAS. Such a limit is an essential component of the ‘see and avoid’ principle when separation is not established by ATC. This is in addition to speed limits, which may be notified for specific procedures.

The 250 kt speed limit does not apply to:

1. (1) flights in Class A and B airspace;
2. (2) IFR flights in Class C airspace;

(emphasis mine)

Between SSE11 and CLN, you are actually in class A airspace and technically exempted from the 250 speed limit.

However, most SID/STAR procedures near major UK airports do (re-)introduce the restriction, which is why all corresponding charts (be they from Jeppesen or the AIP, though the former do highlight it in red) specifically mention the speed limit (because it’s actually mandated by the procedure itself rather than the general rule).

So, in theory, after SSE11, you are allowed to accelerate past 250 knots, but in fact you aren’t because the procedure says otherwise (distinct limitation).

What makes it very confusing is, almost all SID and STAR procedures in the UK mandate a 250/FL100 restriction, so you’d think it’s a general rule like in the US, but no – it’s actually implemented on a per-procedure basis.

That’s probably why Jeppesen coded the procedure this way (Navigraph only translates their coding to the appropriate addon format).

And yes, once you are cleared above FL100, it does mean you also need to manually clear the speed in your FMS, which is cumbersome and/or counter-intuitive, but that’s actually a result UK’s somewhat unusual regulations…

Regards,

Tim

[Berzerker]

Thanks for the explanation, but I don’t think that’s really the point of confusion either. Even if it doesn’t apply unconditionally, the chart does say MAX 250 below FL100 unless otherwise authorized, so that takes care of the confusion for below FL100 after SSE11, but above FL100 there’s no restrictions, as per the chart.

If this is truly a Jeppesen coding thing that Navigraph copied, then it is on Jeppesen to either correct it or verify that the chart is correct, because as it stands, the coding and the chart do not agree.

[NAVData]

As I wrote, we will check this with our data provider (because we don’t add something on our own) and when something is wrong it will be fixed in the future. When the coding is ok, than not.

Cheers
Richard