Author Topic: KLAX RNAV Departures  (Read 10103 times)

Offline yqrNINJA

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KLAX RNAV Departures
« on: July 19, 2017, 01:06:32 PM »
Hello all. First post....

I am not a real world pilot, just a flightsim enthusiast.

I noticed something new during RNAV departures leaving KLAX over that past few months. I am wondering what the purpose of the change in phraseology. Once handed off to Tower for TakeOff clearance, the Tower Controller always say "Flight# RNAV DLREY Cleared for TakeOff Runway 24L".  Most pilots readback "RNAV DLREY, cleared for T/O runway 24L" What is the purpose of "RNAV DLREY"? DLREY is the first fix on the departure (ORKCA1), are the pilots not already obligated to fly to DLREY? Is it to point out the altitude restriction at DLREY?

The old LOOP departure had a altitude restriction off the 160 radial off of the Santa Monica VOR (which isn't really RNAV). perhaps to replace that?




Offline tyketto

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Re: KLAX RNAV Departures
« Reply #1 on: July 19, 2017, 08:43:26 PM »
Hello all. First post....

I am not a real world pilot, just a flightsim enthusiast.

I noticed something new during RNAV departures leaving KLAX over that past few months. I am wondering what the purpose of the change in phraseology. Once handed off to Tower for TakeOff clearance, the Tower Controller always say "Flight# RNAV DLREY Cleared for TakeOff Runway 24L".  Most pilots readback "RNAV DLREY, cleared for T/O runway 24L" What is the purpose of "RNAV DLREY"? DLREY is the first fix on the departure (ORKCA1), are the pilots not already obligated to fly to DLREY? Is it to point out the altitude restriction at DLREY?

The old LOOP departure had a altitude restriction off the 160 radial off of the Santa Monica VOR (which isn't really RNAV). perhaps to replace that?

What you are seeing on those departures is RNAV, which is Remote NAVigation. That means that the altitude and speed restrictions are depicted on the chart, and would not be given by the controller. If they are given by the controller, it will effectively cancel any altitude and speed restrictions depicted on the departure.

With this being RNAV to DLREY, as you'd see on departures off of 24L, this means that the pilot must comply with the heading, altitude, and if listed, speed restrictions up to and including the DLREY intersection. This will also allow for simultaneous departures off of 24R, as well as 25R and 24L.

Think about the implications of this. The LOOP departure has an altitude restriction until the SMO R-160 as you stated, but off of 25R, it also has depicted the instruction to turn right heading 220 and await further instruction from the departure controller for the turn back to LAX. Now.. Imagine if someone were on the LADYJ1 off of 25L, with RNAV to HIIPR? that has depicted a 251 heading to HIIPR, to cross HIIPR at/below 3000, then a 256 heading to EVOSE.

See the problem? It completely shuts down simultaneous departures off of runways 24 and 25, and 25L is also used for departures if the crossing at F can not be made for those cargo and private aircraft on the south side of the field.

Additionally, if you also look at the ORKCA1, you'll notice that every departure is given the same heading and altitude restrictions, ensuring separation is kept all the way until vectors could be provided, which would be to KLIPR, at or above 10000. You'll see that on page 2 of the chart, which gives you the description.

So in short, RNAV to <intersection> is depicted on the chart, so that the chart tells the pilot what they have to do. They still have to check in with ATC, but as the chart tells them what they should do, RNAV to <intersection> gets them to comply with the chart; because if ATC tells them something else, it cancels the chart until ATC tells them to resume the departure or, in the case of RNAV departures, CLIMB VIA THE SID.

Additionally, you'll find this in use at any airport that has simultaneous approaches and departures in use with parallel runways. KLAS uses this when 1L/R are in use. SLC uses this for the 34s and 35s. KSEA uses this when when either the 16s or 34s are in use. KDFW uses this for when the 17s/35s or 18s/36s are in use. So when simultaneous departures are in use with parallel runways, you'll hear "RNAV TO" frequently.

BL.
« Last Edit: July 19, 2017, 08:46:03 PM by tyketto »

Offline yqrNINJA

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Re: KLAX RNAV Departures
« Reply #2 on: July 20, 2017, 09:41:31 AM »
Great reply. I understand completely. Thank-you for taking the time. ATC is fascinating.

Offline dawgweed

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Re: KLAX RNAV Departures
« Reply #3 on: August 20, 2017, 11:16:41 AM »
RNAV means Area Navigation; not Remote.

RNAV is a method of navigation which permits the operation of an aircraft on any desired flight path; it allows its position to be continuously determined wherever it is rather than only along tracks between individual ground navigation aids.


The reason that ATC states the initial RNAV point in take off clearance is that there were too many occurrences of departing aircraft flying the incorrect procedure.

https://www.faa.gov/documentLibrary/media/Notice/N7110.595.pdf

Offline porterjet

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Re: KLAX RNAV Departures
« Reply #4 on: October 23, 2017, 10:18:04 AM »
As dagweed says it is one last check for the pilots. As the tower says"RNAV to DLRAY..." The PNF is supposed to glance at the FMS to verify DLRAY is the TO waypoint. If not they have either the wrong SID or the wrong runway selected.