Flight plan route query
 

Just after a bit of clarification for flight plan requirements after chatting to someone a fair bit wiser than me.

Taking off from point A, which also has a 5-letter IFR waypoint over the top of the airfield going onto a route (or even as part of a route), then landing at point B, again with say another 5-letter waypoint (over the top of the airfield) at the end of the route, I was wondering how this should be submitted.

If there was an actual aid at either airfield I’d obviously plan via the aid to join/finish the route, but if not would just go airfield A dct route designator, dct airfield B.

e.g. YAAA DCT Z99 DCT YZZZ

My wiser colleague says airfield A - 5-letter waypoint - route - 5 letter waypoint - airfield b.

e.g. YAAA DCT ABCDE Z99 ZYXWV DCT YZZZ

which is more correct?

I’ve already consulted the ERSA FPL requirements, and ENR 1.1, but can’t find anything substantive either way.
The waypoints are identical to the airfield reporting point lat/longs.

Been a while since I was in the ops department but my recollection is that if YAAA and YZZZ are not nominated as part of the overlying airway then you plan via the waypoints as a means of joining/leaving that airway.

You mention planning via the aid if there was one at either/ both airfields - the 5 letter code is a substitute for that. The system needs to know at which point you are joining/leaving the airway and using the waypoints achieves that.

Re “which is more correct?” - I’m with your mate - one is correct, one isn’t..

6 of 1, half a dozen of the other however, looking at the ERSA FPL and what usually gets filed, if the aerodrome has a waypoint allocated above(intersection) on an airway then the 5 letter waypoint should be used then DCT

eg, flight from YTWB-YCCA

DCT BIVAT Q303 YCCA DCT

if YCCA had a waypoint above

DCT BIVAT Q303 XXXXX DCT

Thanks for the clarification!

It only came about with one of our regular destinations gaining a 5-letter waypoint- up until then I'd never thought about it, or had ATC grumble about it.

Cheers!

LSALT
 

The route LSALT is calculated from the points on the airway. If ABCDE is at exactly the same coordinates as YYYY then not an issue but a lot of ABCDEs exist because a navaid was decommissioned sometime in the past - and it was the navId that was on the airway and not the aerodrome. At big aerodromes the aids are often a long way from the ARP.

So routing from YYYY not via ABCDE technically means you need another method of calculating LSALT.

An airway is like a bus route, and the waypoints along that airway bus stops. You have to tell the ATC system not only what bus you intend to ride, but also which stop you are getting on and off at to define your journey.

To me this doesn't tell you correctly where the flight originated nor where it is going.

From where are you leaving to go direct to BIVAT and after YCCA you're going direct to where?

Per BEVLY9 post, that is the route section for a flight from YTWB-YCCA

I can see she might have left YTWB off at the start but what's the purpose of DCT after the destination?

From a flight note submission point of view , you put in your departure point and destination seperate to the enroute waypoints so those “DCT” would imply to/from said points

YCCA is the intersection on that particular airway.
Which I think again raises the original question because planning

BIVAT Q303 MORRO DCT
BIVAT Q303 DCT
BIVAT Q303 YCCA DCT

all get you to YCCA the same way

My two-bob's worth: there are three components of a flight, the departure and getting onto the route, flying the route, then getting off it and arriving. Checkboard's bus analogy is good.

In BEVLY 9's flight from YTWB to TCCA, the actual route is BIVAT Q303 YCCA, but you have to get yourself onto that, then off it at the other end.

If you're putting in a full flight plan, the departure airport (YTWB) and the destination (YCCA) are already in the notification from the fields you've completed. So what is needed is to link the Dep and Dest to the route. This is done in the Route field (Field 15 of the ICAO Flight Notification) with "DCT" at each end:

DCT BIVAT Q303 YCCA DCT

This tells the system you'll be flying from YTWB direct to BEVAT to join the route, then at the end, you'll be leaving the route at YCCA (final waypoint) to land at YCCA (airport).

The "YCCA" is the route may seem superfluous but it is acting as the destination "navaid". In the big scheme of things, possibly not critical for a VFR OCTA, but unless you know that the waypoint over your airport, you should use the enroute waypoint/navaid as the tracking point before you land.

The whole flight string therefore will look like this:

YTWB DCT BIVAT Q303 YCCA DCT YCCA

The issue is more important when departing YCCA (ie without a navaid). Depending on the nav system being used, you can get into bother if you depart and just hit LNAV, because you may not be joining the planned route but doing a Direct To. For example, take the YCCA to OPIPO segment. In my machine, if I depart with YCCA as the departure airfield and OPIPO as the "first" waypoint, when I hit LNAV the box takes me straight to OPIPO; it won't join the YCCA-OPIPO segment. If I put in YCCA as a waypoint before OPIPO (ie YCCA becomes the departure waypoint, additional to the departure airport), after I takeoff from YCCA, it will then manoeuvre to join the YCCA ("departure waypoint/navaid") - OPIPO segment, which is what I planned.

For the use of "DCT" when flight planning, check out the bottom of page 23 and 24 of AIP ENR 1.10 (note the non-sensical text in point b! :eek:)