Jumbo Driver
23rd Mar 2006, 10:33
A question has arisen (via a thread creep in the ATC Issues Forum) regarding Speed Limit Points (SLPs) while flying a STAR, namely whether a SLP shown on a STAR Chart still applies if you are given radar vectors while flying the STAR (which frequently happens), thereby arguably being taken off the STAR. Common sense would seem to say "Yes", however, if that is so, it is not always easy to see where the speed reduction should be made.
The obvious cases would seem to be:
If the SLP is a fixed point on the STAR (and you are not routing through it), then you may choose to reduce speed abeam this point.
If the SLP is shown as a radius (dme) from the holding fix (e.g. BNN), then you may elect to reduce speed at the same dme - even though you may not now be routing via the STAR holding fix.
However, it seems equally valid to say that, by being given a radar vector, you have been taken off the STAR and therefore the original published SLP and all other constraints no longer apply.
There seems to be ambiguity within both pilot and ATCO fraternities and I for one cannot find a definitive answer.
It is interesting to note that on another thread http://www.pprune.org/forums/showthread.php?t=212064 there has been discussion about whether a change in flight level given when flying a SID cancels other constraints (such as published step climb levels) within that SID. Here, the definitive answer seemed to be tucked away within a CAA Safety Leaflet - RTF Discipline - Advice to Pilots, http://www.levelbust.com/downloads/s...eaflet_rtf.pdf, which says on page 4:
"When an amendment is made to a clearance, the new clearance must be given in full to the pilot by the air traffic controller, and this new clearance automatically cancels any previous clearance.
Thus, when an air traffic controller issues a clearance, which amends the route or vertical profile of an aircraft on a SID, e.g. 'climb FL 120', this automatically cancels the vertical profile of the SID. If the profile contains a restriction which provides vertical separation from conflicting traffic on another SID, air traffic controllers must reiterate the restriction, e.g. 'climb FL120, cross XYZ 5000 feet or above'. Similarly, when air traffic controllers issue instructions which amend the SID route, they are to confirm the level profile to be followed e.g. 'fly heading 095, climb FL 80' or 'route direct to ABC, stop climb at altitude 5000 feet'.
Similarly, if the original clearance included a restriction, e.g. ‘cross XYZ FL180 or below' then the issue of a revised clearance automatically cancels the earlier restriction, unless it is reiterated with the revised clearance."
It can be argued that giving an aircraft a heading away from the horizontal profile of the STAR is the same in principle as the example above and therefore a radar heading effectively cancels the STAR, together with any vertical or speed constraints of the STAR, unless specifically reiterated with the revised (i.e. heading) clearance. It is also a very short logical step to say that, if the published STAR requires, for example, "250kts 15nm before XYZ" and you are then put on a heading such that you are no longer routing via XYZ, then the SLP clearly cannot still apply - unless of course it is restated with the revised (i.e. heading) clearance.
It does seem that the critical question is whether the SLP is just a constraint of the STAR or does it apply to all inbound flights to that destination. By way of an example, the chart for EGLL STARs via Bovingdon (http://www.ais.org.uk/aes/pubs/aip/p...s/32LL0702.PDF) would seem to show the SLPs drawn as a distance to (or radius from) the inbound holding facility (i.e. BNN in this case) - and this would seem to be confirmed by Note 2 on the chart, which says "Cross SLPs or 3mins before holding facility at 250kts IAS or less".
However, this is not definitive and it would be helpful to find clarification similar to the SID case above. Until this happens, I have suggested the simplest solution is to reiterate the SLP requirement with any radar heading off the STAR for, as they say, "the avoidance of doubt", e.g.
"Speedbird 123, radar heading 160 degrees, be at 250kts or less by 17dme Bovingdon."
Can anyone find a reference to resolve this, please - or indeed offer a better answer ... ?
The obvious cases would seem to be:
If the SLP is a fixed point on the STAR (and you are not routing through it), then you may choose to reduce speed abeam this point.
If the SLP is shown as a radius (dme) from the holding fix (e.g. BNN), then you may elect to reduce speed at the same dme - even though you may not now be routing via the STAR holding fix.
However, it seems equally valid to say that, by being given a radar vector, you have been taken off the STAR and therefore the original published SLP and all other constraints no longer apply.
There seems to be ambiguity within both pilot and ATCO fraternities and I for one cannot find a definitive answer.
It is interesting to note that on another thread http://www.pprune.org/forums/showthread.php?t=212064 there has been discussion about whether a change in flight level given when flying a SID cancels other constraints (such as published step climb levels) within that SID. Here, the definitive answer seemed to be tucked away within a CAA Safety Leaflet - RTF Discipline - Advice to Pilots, http://www.levelbust.com/downloads/s...eaflet_rtf.pdf, which says on page 4:
"When an amendment is made to a clearance, the new clearance must be given in full to the pilot by the air traffic controller, and this new clearance automatically cancels any previous clearance.
Thus, when an air traffic controller issues a clearance, which amends the route or vertical profile of an aircraft on a SID, e.g. 'climb FL 120', this automatically cancels the vertical profile of the SID. If the profile contains a restriction which provides vertical separation from conflicting traffic on another SID, air traffic controllers must reiterate the restriction, e.g. 'climb FL120, cross XYZ 5000 feet or above'. Similarly, when air traffic controllers issue instructions which amend the SID route, they are to confirm the level profile to be followed e.g. 'fly heading 095, climb FL 80' or 'route direct to ABC, stop climb at altitude 5000 feet'.
Similarly, if the original clearance included a restriction, e.g. ‘cross XYZ FL180 or below' then the issue of a revised clearance automatically cancels the earlier restriction, unless it is reiterated with the revised clearance."
It can be argued that giving an aircraft a heading away from the horizontal profile of the STAR is the same in principle as the example above and therefore a radar heading effectively cancels the STAR, together with any vertical or speed constraints of the STAR, unless specifically reiterated with the revised (i.e. heading) clearance. It is also a very short logical step to say that, if the published STAR requires, for example, "250kts 15nm before XYZ" and you are then put on a heading such that you are no longer routing via XYZ, then the SLP clearly cannot still apply - unless of course it is restated with the revised (i.e. heading) clearance.
It does seem that the critical question is whether the SLP is just a constraint of the STAR or does it apply to all inbound flights to that destination. By way of an example, the chart for EGLL STARs via Bovingdon (http://www.ais.org.uk/aes/pubs/aip/p...s/32LL0702.PDF) would seem to show the SLPs drawn as a distance to (or radius from) the inbound holding facility (i.e. BNN in this case) - and this would seem to be confirmed by Note 2 on the chart, which says "Cross SLPs or 3mins before holding facility at 250kts IAS or less".
However, this is not definitive and it would be helpful to find clarification similar to the SID case above. Until this happens, I have suggested the simplest solution is to reiterate the SLP requirement with any radar heading off the STAR for, as they say, "the avoidance of doubt", e.g.
"Speedbird 123, radar heading 160 degrees, be at 250kts or less by 17dme Bovingdon."
Can anyone find a reference to resolve this, please - or indeed offer a better answer ... ?