Are IFR airways an anacronism in a TSO146a GPS world?

[ForkTailedDrKiller]

The "Greenie aviation" thread got me thinking, why don't we fly more "direct to"?

I can understand the need for IFR airways in the "olden days" when we used to fly from navaid to navaid, but with GPS, particularly TSO 146a GPS, that is no longer necessary? So why are we still required to flightplan, as I understand it, to fly IFR designated routes or airways when in controlled airspace under radar coverage?

I can understand it when outside radar coverage it helps ATC know where I am, and I know some of the waypoints are ATC frequency/handover points but are they essential when within radar coverage? Does the radar system allow controllers to mark a point handover point?

For example, the designated IFR route from Townsville to Rockhampton is: YBTL-WALTA-BWN-MK-MURPH-YBRK
but lately, once I change to TL Appr, I am being given "track direct to MURPH"! Yippe! Way to go!

Why not "track direct to Rockhampton"?

A couple of months ago I decided to push the envelope a bit and flightplanned Toowoomba direct Townsville. On departure YTWB, once established with BN Centre I was cleared "direct Townsville", but I think that, theorectically at least, I am supposed to flightplan via designated IFR routes where possible.

Any ATC out there able to enlighten me?

Dr :8

[Dragun]

It's to keep a structured environment to allow planning for arrivals and departures and to keep separation standards. If everyone just flew DCT to everywhere they wanted to go it would be complete chaos and very hard work for controllers. Hence the reason the flight planning requirements are only in controlled airspace.

They will often give you tracking direct to a waypoint prior to your destination (e.g. murph instead of DCT RK) as it will be from there they can sequence aircraft in an appropriate order for the approach depending on size and speed. These 'sequencing' waypoints also differ for jets and other aircraft for the same reasons e.g. BIK and RIVET at Sydney.

In saying that, ATC will give you direct tracking when their workload or the traffic situation allows.

The 'direct to' function doesn't change on the TSO of your GPS. The only difference between TSO146 and 129 is essentially the legality of its use e.g. sole means vs. primary means and alternate requirements depending on your operation.

[Spodman]

AIP ENR 1.1 20.1. The pilot in command must plan and conduct a flight in accordance with the route specifications and applicable flight planning requirements published in GEN 3.2 and ERSA GEN when:
a. proposing to operate under the IFR on any route segments, or
b. proposing flight in controlled airspace, unless otherwise authorized by ATC.

20.4 Where no route specification has been published in the relevant en route chart, a route determined by the pilot in command, and, if in controlled airspace, approved by ATC, will be planned.

An example - YWKB DCT YPOD – All OCTA. Your GPS means you comply with GEN 3.2, there is no published route. There is a published route via HSM & HML, but this is irrelevant. Fill your boots.

Any affect? If you are buzzing along OCTA below a published LSALT you are more likely to be quizzed by even a busy ATC. In the days of Flight Service this would have vastly increased the workload of processing your flight, as you are ‘off the rails’. No real affect now. Requirements of position reporting must still be met by you.

Another example – YMEN DCT YPPF – 8,000 FT, partially in CTA. As above, but the route must be authorized (before you put the FPL in) by ATC. They will say, “NO”. (In other cases, particularly if it doesn’t affect areas close to the big airports they may say, “yes”).

ERSA GEN says depart EN by a variety of ways, but only defined to the first waypoint outside CTA, you pick DCT EN ML H345 NEVIS. After departures has finished organizing you with his other traffic you will get DCT NEVIS maybe without going anywhere nearer to ML than when you were parked at EN.

ERSA GEN says arrive PF from the SE via H345, but this only means for the bit in CTA. You can plan DRINA H345 AD PF DCT, then try your luck for direct with the clearance.

As above, your call what happens in between NEVIS & DRINA, DCT if you want.

So, either EN ML H345 AD PF, or EN ML H345 NEVIS DRINA H345 AD PF for more typing and less flying.

This is how I understand it. If I’m wrong I’d like to hear about it.

[NOtimTAMs]

With a TSO146a GPS unit you are always able to fix your position legally (and continuously!), so the 2 hourly navaid fix requirement becomes irrelevant until the GPS goes Tango Uniform.

On a recent YSBK-YBNA-YBCG flt in CTA at flight levels in rather lovely weather I was denied IFR CLRNCE DCT BNA from a bit past past Maitland (edge of C into E) - so as soon as I could I cancelled IFR, "dropped" to VFR status, climbed 500' and went merrily on my way....That being said, some controllers have approved fairly lengthy DCT legs on similar routings.

[Spodman]

Had another look at your question & thort I'd give more of an answer. If a clearance is involved by my references above ATC prior approval is required. If you plan direct anyway ATC are not policemen and whether you get a clearance or not will be affected by how inconvenient or otherwise what you have planned is.

If your plan is very inconvenient they may offer a route that isn't. If they are really busy they might just say, "NO"! Your call.

[OZBUSDRIVER]

Been thinking about this. Prior getting clearance DCT, would it be prudent to expect the TO to be a common entry point for the STAR at destination? Keep thinking about gates of entry, the busier it gets the further out the gate is to facilitate sequencing. Would that work?

Sorry if a dumb question.

EDIT doooh DRAGUN answered it for me. That would be a YES and YES

[Brian Abraham]

You be wanting some thing like this Doc? Perhaps the shortage of ATCers may bring it on, else you fly TIBA. Where did you say ADS-B was at?

Free flight (air traffic control) - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Free_flight_(air_traffic_control))

http://www.accs.uq.edu.au/documents/WinterSchool05/FFATC.pdf

[Dragun]

Spodman

Nice lengthy responses but isn't that exactly what I wrote in the first place without all the references?