ESTABLISHED on a DME ARC ?

[Checks]

FNG is an idiot.

Anyways, back to the original question. I have only flown a DME arc once in my life(CFII checkride) and I remember 1mile being the tolerance off course. What I cant remeber is if that is 1 mile total tolerance or 1 mile either side.
EXAMPLE:
11dme arc...off course at 12 DME or 11.5?

Thanks

 

[AWACoff]

1 mile either side ie. 11 DME arc means between 10 and 12 miles.

On a side note, my Jepps didn't discuss what "established" means either. There must be something out there that is less ambiguous than the P/C glossary.

 

[A Squared]

well, I don't know what the official "chekride" definition of "established" on a DME arc is. From a practical "when is it safe to descend" viewpoint consider this: the obstruction clearence criteria for a initial approach segment based on an arc is essentially the same as for an airway, 1000 feet out to 4 miles either side, then 500 feet tapering to 0 for 2 more miles. In other words, if you're at 10 DME on the proper altitude a 10 DME arc, you're at least 6 miles from anything at your altitude or above. Does this mean you can start down at 16 out on a 10 DME arc? well that would be a little unwise, but if you're inside of 2 miles and turning and the arc is coming in nicely, you're really going to have to do something wild in order to hit something.

regards

 

[Ty Webb]

A Squared:

Nice to have you weigh in on this one . . . but if you really want to participate in this string, you're going to need to insult someone's mother or at least become blasphemous. Just simply paraphrasing the TERPS manual isn;t going to cut it, not for for this string. . . . no how, no way.

WFWT

PS- thought about pulling the ol' "weedwhacker" out of storage, but decided against it.

 

[A Squared]

>>>>>you're going to need to insult someone's mother

Ummm, OK ... your mother flys a sloppy ILS

>>>>or at least become blasphemous

OK....Did you hear about the dyslexic, agnostic, insomniac.........?



PS- thought about pulling the ol' "weedwhacker" out of storage, but decided against it.

hehe .... a classic like the weedwhacker should be saved for special occasions .... this tool doesn't merit it.

regards

 

[The FNG]

Oh, you weren't finished yet. Well, allow me to retort...

(Hey somebody's gotta put some personality into this thing!)

Lets see, where to begin...

Ok, the fun(ny) stuff.

[I have been posting to this board for over five years, and have learned a long time ago blah, blah, blah...]

Five years! Wow, you really are King Sh*t of Turd Mountain!

[Considering I have a monsterous pile of automation-related documents and materials sitting on the floor right now, containing an analysis of the Cali crash in detail, no thank you.]

Oh yeah, I bet my mounstrous pile of stuff is bigger than your mounstrous pile of stuff.

[FNG is an idiot]

Ok, I'm the idiot but you're the one one who's only flown one DME arc and doesn't know di*k about it? Hmmm...

[...haven't even figured out yet how little they truly do know- both about life, and about our profession]

Since we're playing armchair psychologist let me have a crack at it.

(Stately older gentleman sitting in a leather wingback chair, reading glasses lowered slightly...)

"It's NOT about WHO'S right. It's about WHAT'S right."

Some of you just don't get it. Playing one person against another will never get you anywhere in a conversation, a debate, or "life" (Ty).

Debate the subject. Period. Everything else is a waste of time. I see more quoting here than anywhere else; and people chiming in saying someone's wrong, or I'm right, or they're right.

[Sorry, Chief, but he's right . . . . and you're wrong.]

What kind of juvenile bullsh*t is that?

Of course, this idea requires a higher level of understanding of the concepts of interpersonal relationships. So I can see it going over some peoples heads (I won't even say it).

And just to set the record straight, I was the one quoted first, (with an offhanded comment to boot) followed by a blindside post with the first name calling. Hey, I'll go toe-to-toe with anyone but what kills me is the people who pick a fight then when the going gets rough cry about their p*ssy hurting. Besides, I'm just having fun, while some of you are actually serious.

Oh yeah, here's another one: "Take your job seriously, but not yourself."

So to reiterate, "It's about WHAT'S right, not WHO'S right."

And for those into cliche's, "Fix the problem, NOT the blame."

So lets stick to debating the issues so people who don't know how to fly DME arcs but call people names can learn something.

PS: Nobody has even attempted to debate the technical elements of my previous posts. What's up with that? (But, if you want to sling mud I can do that too. Weehaaa!)

 

[100LL... Again!]

FNG-

Although your aviation dogma is entertaining to read, you are in over your head when it comes to the actual facts here. You are absolutely wrong. If you want to wait until you have a centered needle before descending, have at it. But to impugn the professionalism of pilots who apparently are more well-read on the topic is not helpful. By the way, you lobbed the first grenade.

It reminds me of the attitude of a lot of regional new hires that feel a need to teach the captain how to fly the aircraft - after all they are the one with the flashy degree from an aviation university.

Your point about side lobes is correct, but no one is advocating a descent to the inbound altitude just 'cause the needle twitched a little. Besides, who is so positionally unaware that they can't tell a side lobe from the real thing (couldn't resist). Also, side lobes behave VERY differently than the course centerline, and will not produce stable indications.

Also, you assert that flying an entire approach with the needle half a dot off center is not established? Laughable. Before you make the obvious slam, I fly 'em centered, but that's beside the point. I guess you are the safest pilot in the world.

Ignorance is optional.

Quick trivia questions:

#1 How far outbound can you fly from the IAF on a typical approach at the PT altitude before you theoretically hit something?

#2 If the PT altutude is 3000, but you arrive at the IAF at 3500, what is the criteria for beginning a descent?

a. Arriving at the IAF
b. Turning outbound
c. Course alive outbound
d. Needle centered outbound

The answer may surprise you.

 

[A Squared]

#1, 18 miles

#2, A, unless the procedure specifies a minimum altitude to maintain until established outbound from the IAF, the manuvering area and the entry area provide the same obstacle clearence.

 

[midlifeflyer]

On a side note, my Jepps didn't discuss what "established" means either. There must be something out there that is less ambiguous than the P/C glossary.

Why "must" there be? Not =every= detail of =every= operation =has to= be defined. (Of course, for some people it does - it's a personality thing)


The FAR doesn't contain a definition. At least suggests that the definition is =intended= to be loose, perhaps contemplating the use of different nav systems or even different opSpecs.

 

[80/20]

TonyC are you asking for cockpit nav indications that defines "established on a DME ARC"? (Or for the point on the arrival where you can continue the descent?)

 

[The FNG]

Lots of good points. And I'm willing to admit "I'm" wrong if that's the case. (and there's that "you're" wrong, not "what's" wrong thing again - I still don't get it) So, if someone more well read has a definative answer please post the reference. Not sure what "over your head" means but if you're willing to elaborate I'm all ears (eyes?). I will add that a certain training department office is amused by this discussion.

Further, I didn't say flying an approach 1/2 dot off center is not established, but rather having centered and thereafter remaining within limits; vice never centered and thereafter waffeling around trying to get "established" while descending. Case in point: the crash of Secretary Ron Brown in Bosnia shooting the dual NDB into Dubrovnik. (Been there, done that, got the t-shirt) That's what can happen.

Semantics? Absolutely. Should everything be defined to a gnats ass? Not necessarily. But some things are worth talking about.

So lets talk about "course alive". Course alive occurs well before flight director capture. Shouldn't that mean something? I don't know what the tolerance is and I know it's not needles centered. But I'm ok with FD captured because it's been certified. I'm not ok with plain ol' course alive. I still think "striving" for centered is the safest approach. Who can argue about that (someone I'm sure)?

 

[100LL... Again!]

A squared gets an A+ Bravo!
--------------------------------------------------

FNG-

There are some autopilots that capture the loc before the live needle.

I guess I don't care if a training department thinks that this is amusing, since there is SOME importance to this issue. A while back in an issue of the ALPA magazine, an article was written about a MAJOR airline where the flight department wrote a letter to the FAA saying that the approach into JAC was improperly designed. The FAA wrote back and said "You're flying it wrong."

The article is called something like "No Shortcut Here"

This means that enough pilots flew it wrong and brought it up to their flight department that they felt they needed to write a letter. Probably written by a CP or Dir. Trng.

Just goes to show that you need to see it in print before you can believe it. Even then...

If the needle is not pegged, you are in safe airspace.


Quiz #2:

How much obstacle protection on the final approach course of a VOR approach?

a. 250'
b. 300'
c. depends on temperature
d. all of the above are possible answers

 

[80/20]

Quote:
_______________________________
Singlecoil said:
Course alive on a procedure turn on a VOR or ILS/LOC means you can let down.
_________________________________

This started a good discussion, which is what makes this forum good! I knew I had read about this somewhere and started looking for the source. First, AIM, TERPS, FAA Orders and US Gov Specs for IAPs but no result. It really bugged me because I knew it was hidden in some obscure source document. Finally I found it: ICAO Doc 8168-OPS/611, Procedures for Air Navigation Services - Volume 1, which simply says:

"Established" is considered as being within half full scale deflection for the ILS and VOR or within +/- 5 degrees of the required bearing for the NDB.

Note: This is given specifically for the inbound course/final approach.

Not just a theoretical issue, if you are heavy with tailwind at altitude and on a steep approach it can be difficult to get down unless you start as soon the chart maker's intened.

FNG points out the risk with side lobes (false localizer beams). Any approach that has problems with this within 10 degrees of final must have a non-standard warning. Example: "LLZ only to be used inside +/- 10 degrees of front beam"

 

[A Squared]

OK, if you insist:

D all of the above.

a) A VOR approach with a FAF gives 250' of obstacle clearance,

b) A VOR approach with no FAF gives 300' of obstacle clearance,

c) those clearances are predicated on the correct *true* altitudes, for a given indicated altitude, the true altitude will be lower with lower than standard temperatures. For example, assume an MDA of 600 feet HAA, 300 foot obstacle, and 300 feet of clearence on a VOR with no FAF. If the temp is -40, and your altimiter is correctly set to the altimeter setting for that airport, and you are at 600' indicated, your actual altitude will be 455', still enough to clear the obstacle, but not by much.

regards

 

[canadflyau]

I'll keep this short.. Being established is as pointed out earlier, 11DME is 11DME, 13,000 is 13,000, etc etc. but correct me if I am wrong, but for each one of these are acceptable tolerences establised in the FAR/AIM, ie +or-1 mile is within tolerence for the DME arc procedure.. if you are outside of this, you are not "estblished." They even let us know how wide a Victor is and how to figure out if we are in those established tolerances..

I fly a DME arc at several airports in fairly dense airspace, and if you don't call "established on the 15DME arc" within seconds of being within +or- 1 mile (depending on which direction they vector you from) ATC will call you asking "are you established?"

my .02

 

[100LL... Again!]

Tip 'o the hat to A squared.

 

[80/20]

Singlecoil talkes about when you can start your descent on the inbound track. He suggested that you may initiate this while you are trying to get 100% aligned with the track. I do not think that he intends to say that it is ok to fly the approach down to minima with intentional deviations.

The width of the obstacle clearance area at the part where the final approach course/inbound track is anticipated to be intercepted is wide enough to allow Singlecoils technique (It should be half of full scale deflection for ILS/VOR and +/- 5 degrees for NDB). That does not mean that you always should squeeze yourself down to the lowest limit. A Squared points out metreological factors that the TERPS expects the pilot to consider. There have been many incidents with very close to the ground flights caused by minima not corrected for cold weather. Some airlines that routinely operate in cold weather will use a table with values to be added to published minima.

 

[Singlecoil]

80/20 is right on on this one. I did a search on the Practical Test Standards for Instrument and ATP thinking they would be the same on this issue. They are not. They hold you to different tolerances regarding tracking the radial or course inside the FAF, but don't say when you can descend.

I agree that the most neglected point here is temperature. The PTS don't even mention it, yet you can find yourself 700 feet low on a very cold day in Alaska or Montana and still think everything is fine. What is worse, some Minimum Vectoring Altitudes in mountainous areas are only 1000 feet AGL. On a cold day, you might be only 300 feet over the mountains, but ATC thinks you are 1000 feet AGL because your mode C transponder is lying just like your altimeter. In Canada they correct for this with MVA's but in the US they don't. I've filed NASA reports on this but haven't heard a thing in reply. This is not a problem unless you fly near mountains, then you better give yourself some extra altitude if the temperature is colder than standard.

 

[80/20]

Cold weather altitude corrections enroute.
A rule used by several operators: Add 4% per 10C below standard.
Note that you must request a higher altitude if you don't want to maintain an assigned altitude that you think could be too low. ATC does not correct their minimum vectoring altitudes for low temperature.

Use a computer or table to adjust approach minima. A table is quick and easy to use. Non-precision approach minimum altitudes could require adjustments from 40 to more than 100 feet on a cold winter day.

 

[100LL... Again!]

The amount of cold-weather variation depends primarily on two things:

#1 HAT or HAA for the approach. The higher the altitude AGL. the larger the error can be.

#2 Temperature. The colder the temp, the larger the error.

Therefore, there is more potential to be significantly low on an approach with a HAT of 900' than on one with a HAT of 350'.

The real danger can occur on PTs that are extra-high due to rising terrain, since the HAT on the PT could be a few thousand feet on the outbound.

Th higher the aircraft is above the weather reporting point, the worse the error.



Additionally, wind over mountainous terrain can noticeably affect the pressure in the vicinity of the aircraft and change the pressure lapse rate from the surface to the PT altitude, for example. Some consideration is given for this type of terrain when determining minimum altitudes.