Diversion from SID
 

Hi all

I have a question directed to pilots about a divergence from a sid.

A business jet had to depart on a sid with a right turn at 2000 feet. A couple of minutes before a very slow IFR plane had departed on that same sid.

Of course the business jet would have caught up with the previous one quite fast. To be more expeditious and less fuel burn for the jet, what I did was to let him climb higher and make it a left turn towards the last point on the sid.

A colleague of mine said "you shouldn't do that, pilots don't like being taken of off their sids". I completely understand that, but I think they would hate it more that they would be leveling off beneath the other one for some time before continuing there climb.

I'm not a pilot myself but I think the instruction "turn left to XXX" is not so difficult and thus I want some opinions from pilots on this matter.

We normally welcome a direct turn the the terminating point of the SID. The only time we might decline it is for weather reasons or if terrain is an issue given that in some places we might get an instruction like "you may turn left direct XXX with your own terrain separation".

At many airports, such a diversion from SIDs is rather the norm than the exception. Usually, it is a direct to a point further down the route, vectors for shortcuts or, possibly, also a route around a slower traffic. There is also the mentioned instruction "when passing x ft, turn right/left etc.".

None of these instructions are unusual or only grudgingly accepted by crew - they are taken as they come. If there is sufficient capacity on the controllers part, a quick information about the reason in case of an intermediate leveloff or a longer route is gladly taken as well.

After all, everything that safely expedites the flow of traffic is in the crews best interest...

Do I correctly understand the scenario? Two aircraft were allowed to depart on the the same SID with the faster one last? Why? A radio failure or finger trouble would have made that a very interesting day. But returning the opening question and speaking for myself, I really don't care about being taken off a SID from before just before I roll to just before the reaching the last point. What I really don't like is being stopped from climbing. That really gets my goat.

PM

Hello DaCoke,

Any direct in the SID is most welcome.
However being "short cut" in the STAR (leaving us high on profile) is annoying.

Since we are speaking STAR & SID. Can you confirm, that when cleared direct to; the constraints (altitudes & speeds) associated to the by-passed waypoints are cancelled when flying abeam those waypoints.

Bonne journée

Lots of SIDs around the world have specific mention to the very scenario you describe. For example, Toronto Pearson (YYZ) has a notation in the altitude box for almost every RNAV SID that describes what to do in the case of a tower or departure initiated turn away from the SID profile. In this specific case it is for noise abatement purposes, but as far as I am concerned the controller has the bigger picture, so I go where they tell me to - unless my EGPWS shows red and begins talking to the voices in my head.

As for STARs, Feather44 already mentioned that this can leave us high and fast with some controllers still expecting the airplane to be able to meet all speed and/or altitude restrictions afterwards. The phrase "do your best" often gets chuckles from all the other airplanes on frequencies and grumbling from the airplane it was directed towards.

Feather44, if they say "Climb/Descend via the SID/STAR, cleared direct xxxx" then you are responsible for meeting any previous altitude and/or speed restraints that would normally apply at that waypoint.

If they do not specifically state "Climb/Descend via" and you are cleared to a waypoint, you do not need to meet any previous restriction but you must meet any restriction ahead of you.

This is fairly new here in Canada as we adopt a more ICAO style format, so I've been double checking anyways as a bit of CYA.

Thanks TSRA, I take note.