Confusion about when it's my navigation, and when it's ATC

A Guy Called Tyketto writes:

Okay.. KLAX LOOP4.DAG.KEPEC1 KLAS at FL290?

Yes.

I'll actually give an objective tutorial on this, as it's in the
sector I'm affiliated with and do most of my time in.

OK. I often take my routes directly from FlightAware, so that I'm
flying the same routes people fly in real life. If I'm staying within
SoCal, I also use TEC routes.

Look CLOSELY at those charts, and I mean closely.

Which charts? I have VFR sectionals and TACs, plus SIDs, STARs, and
instrument approach plates, but no IFR charts.

I suggest looking at the KEPEC1 first before the LOOP4. Yes,
it's the arrival and you haven't even departed yet, but you are in the
flight planning stage at this moment, and there is something important
that needs to be learned. The KEPEC1 arrival is an RNAV procedure,
requiring RNAV-capable equipment. Aircraft that are /E, /F, /G, and /R
are RNAV capable. If said aircraft is RVSM capable, then the following
suffixes apply: /J, /K, /L, /Q (FAAO 7110.65, 2-3-7). If your aircraft
is not one of then your flight plan will be rejected because you can
not use the KEPEC1 arrival.

The aircraft is RNAV-capable, but I will grant that I didn't notice
that it was RNAV. I just look at the fixes and so on most of the
time, knowing that ATC will probably tell me to do something
different, anyway.

LOOP4. If your aircraft is not capable of climbing at 500ft per
nautical mile to 10000, you're using the wrong SID. LOOP4 requires it.

The aircraft is capable of this.

I'm going to assume that you a) have RNAV and RVSM capable
equipment onboard and your aircraft is able to meet the climbing
requirement, and that you are familiar with ATC in the terminal area.

Yes, it's a BBJ2 or 737-800, and I know ATC a little in the area, as I
fly around there a lot.

You've received your clearance, and will be cruising at FL290. Great.
ATC clears you to takeoff on 24L.

Yes. More specifically, I was told to climb and maintain 5000.
Departure told me to climb and maintain 15000 (IIRC) and to proceed
direct LAX, which I did.

You best look at the LOOP4 chart again, as you have 2 crossing
restrictions you must meet. You must cross the SMO R-160 at or
below 3000ft.

I believe the FMC knew that, although I wasn't watching to see. ATC
had already told me to climb and maintain 5000, which I assumed
overrode all other instructions.

From there, you should get vectors back to LAX
with something being told to you like:

"Turn left direct Los Angeles, resume the LOOP4 departure,
comply with all restrictions, climb and maintain 15000".

I was told proceed direct LAX, climb and maintain 15000. No mention
of restrictions, though. Had ATC said that, I probably would have
looked back at the plate to see (although the restrictions are mostly
coded into the FMC's database).

In reality, all I really did was dial 15000 into the MCP, letting the
FMC continue its climb, and I plugged LAX into the FMC as the current
leg, forcing it to proceed to LAX directly (LAX was the next leg,
anyway).

You do exactly that. Your restrictions are to cross LAX at or
above 10000, KEGGS at or above 13000, and COOPP at or above 15000.
Sometime at that point you'll be handed to the Center controller who
will climb you to your cruise altitude. That ends the use of LOOP4
unless you end up NORDO for some reason.

I was handed to Center, which then told me to climb and maintain
FL290.

Now, you're en route, and you're ready for the arrival. You're
still at FL290. Staying that high until your FMS starts to descend is
really going to increase your descent rate, as well as try its hardest
to maintain a slow speed for your descent. Not good.

I recall stepping through the legs looking for anything that seemed
like a steep descent and possibly tweaking some legs, although I don't
remember the details.

What I do remember is that I reached the top of my descent and the FMC
started down, then ATC called me and asked why I was low. So I reset
the MCP to FL290 and went back up. Seconds later, Center told me to
cross something at something (I don't remember what now). My guess
was that he forgot that I'd be starting my descent and remembered when
he saw me descending, so he called me on it and then cleared me down.

Also, the DAG/HEC corridor is one of the busiest streams in US Airspace.

It's extremely busy even in the virtual US airspace. The difference
in the simulated world is that pilots look for heavy traffic, whereas
I presume they aren't so thrilled about it in real life.

Just about every arrival into the LA Basin passes in that corridor, and all
northeastbound flights leave the basin through that corridor. You may
have a flight which ATC has positively separated you from, laterally
and vertically. It is best to let them control your descent instead of
asking.

Fine with me. I just wasn't sure about whether I was supposed to
start on my own or wait to be cleared down.

ATC should tell you something like the following:

"Cross MISEN at and maintain FL240".

I recall something like that, but I don't remember the fix or
altitude.

If you look at KEPEC1, you have a segment there where you have
a crossing restriction at MISEN of FL240 or higher. The closer you are
to that, the easier your descent will be for your next crossing
restriction, which is CLARR. ATC will tell you this:

"Cross CLARR at and maintain 13000 and 250kts. Las Vegas
altimeter xx.xx".

Yes, I recall getting that.

From here, you'll be descending and reducing speed for the
arrival, and must hit CLARR at that altitude and speed.

I recall some trouble hitting the descent, but I tweaked it and
arrived at the right altitude and speed. I think starting the descent
late messed it up.

From there, the arrival tells you everything you need to do.
Should ATC have you execute the full arrival, they will tell
you something like:

"Descend via the KEPEC1 arrival".

Unfortunately, they vectored me around, and then told me to follow
some traffic going the opposite way (towards the airport, whereas I
was still headed east). I messed up so much fiddling with the FMC and
autopilot that I couldn't follow the other guy in, so I had to go
around. Then it was more vectors, and following someone else in. I
gave up on the AP and flew by hand towards the other aircraft, then
intercepted the localizer and configured everything for a nice
autoland.

That's it. From there, you're crossing KEPEC below 13000 and
above 12000, IPUMY below 12000 and above 1000, NIPZO above 9000 and
below 1000, SUNST at 8000 and 210kts, KIMME at 210kts, CHIPZ at 170kts.

Yeah, if ATC doesn't send me hither and yon instead.

Look now at the ILS 25L chart. You'll notice that the altitude
you're at by the time you hit PRINO is the same altitude you should be
at for executing the ILS approach from PRINO. So ATC should only have
to tell you:

"After PRINO, cleared ILS 25L approach".

I think ATC was looking to have more fun. In simulation, ATC, like
pilots, tends to look for challenges rather than seeing traffic and
complexity as undesirable.

No PTAC is needed, as the RNAV arrival drops you off directly
on the IAF for the approach. From there, follow the chart down. 8000 or
above at PRINO, 6500 or above at LARRE, 4900 or above at SHAND, 3800 or
above at RELIN.

I wish.

In short, like everyone else has mentioned, just because your
FMS thinks it's okay to descend, doesn't mean that it's kosher with ATC
for you to descend. They may have other things impending your descent.
When in doubt, ask. The worst you'll get back is 'no', and a reason for
why you can't at that time.

OK. I will ask next time. I have yet to do an approach (in the
presence of ATC) that followed the plates, though. Somebody always
wants me to do something different.

--
Transpose mxsmanic and gmail to reach me by e-mail.

In a previous article, Mxsmanic said:
Paul Tomblin writes:

If that upsets you, then let me know so I can join the legion
of people who have you kill filed.

Nothing upsets me, but I'd prefer that you killfile me, just the same.

Your loss.


--
Paul Tomblin http://blog.xcski.com/
"Once you have flown, you will walk the earth with your eyes turned skyward,
for there you have been, there you long to return." -- Leonardo da Vinci.

Milen Lazarov writes:

or you can just request it directly:

N12345: Request block altitude between 15,000 and 17,000.
ATC: N12345 maintain block altitude between 15,000 and 17,000.

I'll try that, thanks.

--
Transpose mxsmanic and gmail to reach me by e-mail.

Milen Lazarov wrote:
On 2007-01-03, Mxsmanic wrote:

Pixel Dent writes:

I think I read this section before; this paragraph sounds familiar. I
always get instructions to "maintain," though. What's the phraseology
when I get a block of altitudes? Or does it even happen with
frequency in real life? How do I request it (or do I even need to
request it)?


From a flight today, west of Billings, MT:

N12345: Unable to maintain 16,000 for turbulence.
ATC: N12345 maintain between 14,000 and 16,000

Yep, we had severe and extreme turbulence pireps near the mountains
today. Bad day to fly anywhere but east from here.

In article ,
Mxsmanic wrote:

Yes, I've had that. Usually the FMC decides what's best, but at least
I can override that and force a descent at a higher rate (provided
that I can tolerate the airspeed increase).

Well, once again I don't know much about airliners, but in smaller
planes at least you don't generally increase airspeed to descend you
reduce power. At least in the area of the country I fly ATC often has
speed restrictions on the airliners so they couldn't increase speed
during a descent if they wanted to. It's good practice to hold your
airspeed steady while reducing power to make your descent.


To really get a feel of how this all works I'd suggest you go to one of
those live atc sites and listen to an approach controller. You'd be
amazed how much you can learn listening to one for a half hour. At first
it will seem chaotic and then you'll realize there are patterns to what
he's doing with the planes.

I have a really hard time just understanding what they are saying
sometimes. I don't know how pilots and controllers manage to
understand each other without making mistakes.

Practice, practice, practice. Everyone has a hard time understanding at
first but the more you listen the more it makes sense.

"John Theune" wrote

Are you flying IFR? if so then ATC will tell you what altitude to be at.
Resume own navigation refers to routing not altitude. VFR is a different
set of rules.

He is flying a simulator "game," so he isn't really flying anything, and has
no consequences to whatever he does.

Get it?
--
Jim in NC

"Mxsmanic" wrote in message
Now, my question is this: If the FMC has a programmed descent in its
route, do I let the FMC start the descent where it sees fit, or do I
force the aircraft to maintain FL290 until ATC explicitly clears me
for my own navigation or for a lower altitude?

The profile in the FMS is for efficiency and does not take other traffic
into account. You must wait until ATC explicitely clears you to another
altitude. If you are about to pass the FMS's descent point, politely prompt
ATC for a lower altitude. Going into LAS, you very well may get vectors off
the planned route so that ATC can adequately space the arrival traffic (in
the real world).

And if ATC's last
instruction had simply been "resume own navigation" or "proceed as
filed," would that mean that I'd be free to begin the descent whenever
the FMC (or I) decides it's best?

No. That would be for lateral navigation only unless explicitely cleared for
different altitudes. Here is an example that one of my colleagues recently
received counseling about. He was cleared via the KORRY 3 arrival into KLGA.
He started to descend according to the profile. ATC asked why he was
descending and to call a number after landing (not good). He was cleared via
the KORRY 3, not cleared to descend via the KORRY 3. Slight difference, but
very important for traffic seperation.

In situations where I can begin the descent at my discretion (assuming
that own navigation implies this), should I tell ATC that I'm leaving
my cruise altitude?

Yes, the Aeronautical Information Manual states that a pilot should advise
when leaving an altitude.

If the FMC has a continuously changing estimate
of lower altitudes in the descent profile, what should I give as my
target altitude? The next fix that has a specific altitude? (Such as
a fix in the arrival procedure)

Yes.

Climbing I think I understand. If I'm told to resume own navigation,
or cleared as filed in the first place, I climb per my flight plan/FMC
profile. If ATC says maintain X, I stay at X until ATC tells me to
resume own navigation or instructs me to change altitudes. But the
descent part still has me a bit confused.

Query ATC for the assigned altitude so that both of you are on the same
page. Climbs are the same as descents. 'resume own navigation' is for
lateral flight. Don't climb unless expicitely assigned a new altitude by
ATC.

D.

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Mxsmanic wrote:
A Guy Called Tyketto writes:

Look CLOSELY at those charts, and I mean closely.

Which charts? I have VFR sectionals and TACs, plus SIDs, STARs, and
instrument approach plates, but no IFR charts.

I just told you. LOOP4, KEPEC1, ILS 25L at KLAS. Those are also
charts.

The aircraft is RNAV-capable, but I will grant that I didn't notice
that it was RNAV. I just look at the fixes and so on most of the
time, knowing that ATC will probably tell me to do something
different, anyway.

You should look at those, because if you choose the wrong
chart, and your equipment can't support the chart you're filing, you'll
be given another SID/STAR to use.

Yes, it's a BBJ2 or 737-800, and I know ATC a little in the area, as I
fly around there a lot.

You best look at the LOOP4 chart again, as you have 2 crossing
restrictions you must meet. You must cross the SMO R-160 at or
below 3000ft.

I believe the FMC knew that, although I wasn't watching to see. ATC
had already told me to climb and maintain 5000, which I assumed
overrode all other instructions.

If you lost your FMC, what would you do? You just can't let
your instruments do everything for you the moment you rotate. I'd
fathom to see what would happen if you were a /A and didn't have an
FMC.

Now, you're en route, and you're ready for the arrival. You're
still at FL290. Staying that high until your FMS starts to descend is
really going to increase your descent rate, as well as try its hardest
to maintain a slow speed for your descent. Not good.

I recall stepping through the legs looking for anything that seemed
like a steep descent and possibly tweaking some legs, although I don't
remember the details.

What I do remember is that I reached the top of my descent and the FMC
started down, then ATC called me and asked why I was low. So I reset
the MCP to FL290 and went back up. Seconds later, Center told me to
cross something at something (I don't remember what now). My guess
was that he forgot that I'd be starting my descent and remembered when
he saw me descending, so he called me on it and then cleared me down.

I doubt it. There's two places where the Center controller
could give you the crossing restriction; one at MISEN, the other at
CLARR. If he gave you the one at MISEN (which I know he did), it would
make the CLARR crossing restriction a lot easier to make.

"Cross CLARR at and maintain 13000 and 250kts. Las Vegas
altimeter xx.xx".

Yes, I recall getting that.

"Descend via the KEPEC1 arrival".

Unfortunately, they vectored me around, and then told me to follow
some traffic going the opposite way (towards the airport, whereas I
was still headed east). I messed up so much fiddling with the FMC and
autopilot that I couldn't follow the other guy in, so I had to go
around. Then it was more vectors, and following someone else in. I
gave up on the AP and flew by hand towards the other aircraft, then
intercepted the localizer and configured everything for a nice
autoland.

They had visual approaches in use. Also, it has been said
befo 99.9% of all landings are hand flown, not autolanding, unless
on a Cat III ILS approach. ILS 25L is not CATIII.


OK. I will ask next time. I have yet to do an approach (in the
presence of ATC) that followed the plates, though. Somebody always
wants me to do something different.


It could be because visual approaches may be in use over using
an instrument approach. It provides more flexibility with ATC, plus
puts separation responsibility back on the pilot. If you were following
traffic, and you were coming in too fast and had to go around, that may
not be ATC's fault. There would be some things you could have done to
slow your speed down.

BL.
- - --
Brad Littlejohn | Email:
Unix Systems Administrator, |
Web + NewsMaster, BOFH.. Smeghead! | http://www.wizard.com/~tyketto
PGP: 1024D/E319F0BF 6980 AAD6 7329 E9E6 D569 F620 C819 199A E319 F0BF

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-----Original Message-----
From: Brad ] On Behalf Of A Guy
Called
Tyketto
Posted At: Wednesday, January 03, 2007 7:48 PM
Posted To: rec.aviation.ifr
Conversation: Confusion about when it's my navigation, and when it's
ATC
Subject: Confusion about when it's my navigation, and when it's
ATC

....
If you lost your FMC, what would you do?
....

He'd reboot - its Windows and Flightsim after all.

On 2007-01-04, Newps wrote:

Yep, we had severe and extreme turbulence pireps near the mountains
today. Bad day to fly anywhere but east from here.

Yep, the ice was not nice either. Seems that tomorrow will be better
so I might get home. :-)