Christchurch Departures

[Flyer 682]

In regard to departures from runway 20 - why is it that some international flights (Australia, Singapore), have to fly all the way to Woodend before they are able to turn, whereas some flights are able to turn more or less straight away?

[Tinstaafl]

Could be several reasons:

* There might be a minimum turn altitude. Different a/c will reach that altitude at different places eg a 4 engine a/c that's heavy, say longhaul ,will take more track miles than a light twinjet.

* ATC might specify for traffic separation purposes.

* The required route might make it more convenient

[Flyer 682]

Appreciate your reply. My feeling on the matter tends towards your second reason, that ATC might specify for traffic separation purposes. I have heard pilots question the need to go in the opposite direction, which in this case is towards Woodend near the eastern seaboard, then track northwest, before heading on a more westerly course. This example relates to International flights to Australia and Singapore. It has been interesting to observe that QF flights using 767's and 747's, do not appear to have to reach Woodend, whereas, invariably SQ flight 298, (which has used 747's and A340's and latterly the 777), does. Could it be that ATC over-utilises the air space, considering it is far from congested. While this emphasises larger safety margins which is to be applauded, might it also mean that it makes life easier for ATC but annoying for long haul pilots. The extra distance would seem to involve an extra 15 to 20 minutes of flight time which does not sound a lot yet seems avoidable and unnecessary.

[kavu]

All depends on your SID (standard instrument departure).
Off 02 (I think this is what you are meaning) you have the following SID's

Woodend One Departure
-Track to OD NDB
-Maintain 3000ft to OD NDB
-Intercept cleared route

Control can then turn you early if required.

Hope this helps

[nzer]

CHC Departures

My experience on both longhaul and shorthaul departures is that once radar identified, and other traffic permitting , ATC cancels the SID and clears you DCT to the next fix or Oceanic Boundary.

[nike]

I agree that NZ space is far from congested, and ATC are not always the hardest working bunch.

Why is it that there is so much variation between controllers?

some give clearences quicker and provide more efficient routing than others.

and before you say it depends on circumstance, voices are easily recognised, and it seems those same voices are always efficient.

and for these efficient ATC individuals i am greatful.

[Flyer 682]

To all who replied thanks very much. Good to learn more especially when the curiosity is aroused. You have been very helpful. Two things though - I am not that au fait with the jargon so what exactly does NDB and DCT stand for. Nike thanks for picking up on my points regarding ATC, congestion etc. because it was the feeling I was getting.
I think a couple of you guys may be ANZ pilots, (correct me if I'm wrong), how do any Q pilots looking in feel about it?

[kavu]

NDB - Non Directional Beacon
DCT - I think it is Direct Course Track or Direct To, Could be wrong
others refer to it as DTK - Direct Track

For more definitions you could look up in the Planning Manual under the General Section.

As for the turning before SID complete it's up to the controller, if the track that the aircraft wants is free then the controller can then turn the plane onto the required track.

SID's are great for departing aircraft just like STAR's, or a approved arrival procedure, are for arrivals. It helps merge the aircraft onto finals. But most times the controller will radar vector the aircraft into the position that he wants.

[Snowballs]

International aircraft departing usually fly straight ahead, to 5000’ before turning towards the hills / mountains. This requirement is for safety / performance / terrain clearance requirements.

Heavy aircraft don’t climb like lightly loaded domestic flights.

They request permission from ATC to climb straight ahead before turning.

Most international operators will have some Christchurch operational limitation in their ops manual.

[Barbers Pole]

SIA Airbus's will sometimes turn east after take off and climb overhead the airport to gain some height before heading to cross the southern alps. Straight performance (or lack of) as they are normally heavy and I belive climb at reduced power so need the extra distance to ensure adequate terrain clearance.

Nothing to do with the ATC' guys, plus if you go off RWY02 there is alot of traffic coming in from the north so sometimes you will not get a turn to the west until you are above them or get radar vectored around behind them.

[nzer]

"Snowballs" - speaking for one operator/type, ie, ANZ and the B767, ex CHC at /close to MGTOW (CHC-SIN eg) you could turn onto a westerly heading at 500 ft off either runway at CHC and meet the climb requirements to MSA/LSALT - no special procedures are promulgated - typically however by the time ATC identifies you, you at 2000ft or so, and take DCT to the gateway from there. Terrain clearance is a PinC/crew responsibility, and condidering weight/performance/terrain and engine failure consideration before MSA/LSALT a crew will decide the most suitable technique on the day.

[CONVAIR]

The example of the right turn and overhead off 02 (or left turn overhead off 20) is sometimes used to avoid turbulence over the alps. I think one international airline recommends a set heading overhead at FL150 if conditions dictate to avoid the turbulence that would be encountered if lower over the hills. Its all about not upsetting the punters coffee.