NOS & DOD IAP's

[Nikes]

Hello, I recently learned that the DoD separately produces Instrument Approach Charts as a result I have a few questions.

What is the major difference Between the DOD Flips and NOS?
(I would think that they could just combine them with NOS since they already include military airports)

Do military pilots have to fly with them or can you use NOS charts?

Lastly, why are the divided into High and Low books?
(I assume that the supplement books are issued between update... then again I shouldn't assume.)

Thanks,

Nikes

 

[Papyco]

I only just started Instrument Ground School here in Primary. I can tell you what I have learned so far, but I am sure that most of these other guys probably know a lot more than I do.

There is no difference in reading the Approach plates. Both the DOD FLIP and the NOS are the same when you are looking at the plates of a particular approach. The major difference between the two publications is that the DOD FLIP has a section for Radar Instrument Approach Minimums. This particular section lists all the different airfields that can provide PAR and ASR approach services. Since there aren’t too many civilian airports that support PAR approaches, they are not listed in the NOS plates. I don’t know why a military aviator would want to buy and use NOS plates when the DOD FLIP plates are free.

I have been told that the High books will be incorporated into the Low books some time in the future. So until then there are still different books for High and Low approaches. Why they are separate in the first place? I don’t know exactly (remember I did just start ground school last week

I am sure that someone on this board probably has a few more things that they can point out.

 

[furloboy]

I believe that the low and high pubs are separate because the books get too thick to easily handle in a small cockpit. Not much room in there. And when it's dark and rainy and you're min fuel it seems twice as cramped.

As a fighter guy I know that we usually only carried the High pubs. There weren't a lot of fields that had only low approaches that were still capable of handling high performance aircraft.

Combining them will be interesting. Might work out as they've shut down about a gajillion bases in the last 30 years.

Anyway, that's my guess.

 

[Yahtzee]

High vs Low Books

Lastly, why are the divided into High and Low books?

Thanks,

Nikes

This is a stretch but according to Air Force 11-217 Vol 1 (I don't have the specific reference with me, but I think it's Chapter 8), high approaches have descent gradients in excess of 1000/nm after the FAF.

I'll ask an USAF Advanced Instrument School grad on Tuesday and see if I can get you a better answer.

Yahtz

 

[Hugh Jorgan]

Re: High vs Low Books

This is a stretch but according to Air Force 11-217 Vol 1 (I don't have the specific reference with me, but I think it's Chapter 8), high approaches have descent gradients in excess of 1000/nm after the FAF.

I'll ask an USAF Advanced Instrument School grad on Tuesday and see if I can get you a better answer.

Yahtz

I don't think so.... as I clear some of those cobwebs from that part of my brain, I seem to remember the final approach segment being the same as the low approaches, while the intermediate approach segment is the steep part, ie. penetrations, etc.

 

[Yahtzee]

IAF...not FAF

Hugh,

Thanks for the catch...it's late and my head is still aching...maybe from a combo of smallpox, anthrax, and typhoid all injected into the same arm.

From 11-217 Vol 1 Chapter 8

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

8.5.2.2. Profile View.

8.5.2.2.1. Altitude Restrictions. Note the altitude restrictions. Minimum, maximum, mandatory, and recommended altitudes normally precede the fix or facility to which they apply. If this is not feasible, an arrow will indicate exactly where the altitude applies. In some cases altitude restrictions are published in the plan view and not in the profile view. This is often the case with multiple IAFs where it is not feasible to show all the routings in the profile view.

8.5.2.2.2. Descent Gradients. Consider the descent gradient. For a low altitude IAP, the initial descent gradient will not exceed 500 feet per NM (approximately 5°); and for a high altitude approach, the maximum allowable initial gradient is 1,000 feet per NM (approximately 10°).

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sorry for the typo...most high approaches are carbon copies of the low altitude versions from the FAF to MAP.

Yahtz

 

[Toro]

I don't know why they're divided into high and low books, but I would agree with what furloboy said. Nearly every US military base I've been to has high approaches (with the exception being mostly Army) while I've only seen high approaches at a couple civilian fields. As a result, you've got big fat low books that usually only cover one state while a high book can easily cover 3-4 states. Since (with the exception of UPT out and backs) we're usually landing at military bases, fighter pilots will carry the low books in their map case, but they want the least amount of crap on their leg, so they'll use the high book and even if they don't fly the entire penetration, they'll reference the final portion of the high approach.

In Europe, there are either so few high approaches (or they are spread so far throughout the different regions) that high and low approach plates are combined into one book.

 

[Nikes]

What is the purpose of the High Approaches? My guess is that it simulates minimum exposure to ground fire, if that is the case do you fly them more often than normal appchs?

Thanks again

Nikes

 

[JCJ]

NACO vs. DOD Plates

A couple of differences

the DOD plates are printed on much sturdier paper than the NACO (formerly NOS) plates - NACO plates are printed on paper sufficiently thin that they could, in an emergency and with some discomfort, substitute for toilet paper.

NACO plates include all published civil airport public IAP's in the geographic area of coverage, but do not include military approaches unless to a joint use civil/military field. Even in the instance of a joint civil/mil field, not all the IAP's might be included in the NACO plates - for example - SPS is joint use civil/mil. there is an ILS to 15C and one to 33C that are published only in the DOD plates, although several other IAP's are published in the NACO plates

DOD plates include mil approaches and some civil approaches. They do not list all civil airports with published IAP's, and they may not have all of the IAP's that exist to a listed civil airport. The approaches published for civil airports are those of "military necessity". For example, ELD has a VOR approach and an ILS, but the ILS is published only in the NACO plates and not in the DOD plates. guess the military doesn't need the ILS at ELD published

If an IAP to a civil airport is included in the DOD plates, it usually is identical to that published in the NACO plates

note that most civil airports don't have category E minimums, but some that have ANG or AFRES aircraft permanently based there do (examples = FSM, STL)

NACO plates also list radar minima, but as previously mentioned these are almost always ASR approach minima only unless there is a joint use civil/mil airport listed. then the PAR minima (if PAR is available) may be listed in the NACO plates as well

I have seen military hi-XXX IAP's but dont know anything about them - nothing I fly flies high enough to actually get to the IAF of those approaches

obviously I have too much time on my hands to collect this trivia

 

[Toro]

What is the purpose of the High Approaches? My guess is that it simulates minimum exposure to ground fire, if that is the case do you fly them more often than normal appchs?

Not sure exactly why they're flown, but it's not to minimize exposure to ground fire. If there were ground threats around, we would come up initial as fast as possible, pitch out and land. The only time most fighters fly instrument approaches is when the weather isn't good enough to fly up initial. Beyond UPT and outside of a check ride, I can't think of any reason why you'd fly the entire penetration for a high approach.

 

[Hugh Jorgan]

What is the purpose of the High Approaches? My guess is that it simulates minimum exposure to ground fire, if that is the case do you fly them more often than normal appchs?

Thanks again

Nikes

Stay higher longer, saves gas...

 

[rainman_02]

Actually, hi- approaches consume more fuel. In an enroute descent situation, you can calculate out the top-of-descent point to make an idle power descent from cruise altitude to the initial approach fix. Because most penetrations require the use of speed brakes and sometimes you configure prior to the IAF and penetrate with gear and flaps, you are burning more fuel than a comparable enroute descent to a low- approach.


As far as why they were created...I will ask around.

 

[Tweetdrvr]

Hugh and YCJ are correct.

Both the civil and mil books have a statement on the front that says they are printed in accordance with inter-agency air cartographic committee specifications and agreements approved by the DOD and the FAA.

Air Traffic Control agencies hate Hi approaches. They usually start in Center's Airspace, transition through approach control's space and end up in tower's space. Before they can approve a high approach, they have to look at the flow and figure out how this guy diving out of the sky is going to fit in behind or in front of someone being vectored around in the low radar pattern. But when you are gas limited such as a fighter might be, it is easier to divert from 10,000 feet or higher than it is to go all the way to a missed approach point or even to a low altitude IAF that may be at 2 or 3,000 feet.

The parenthetical numbers behind the HAT are what the military guys use for ceiling and visibility filing criteria that allow us to carry a little less fuel than if we filed based only on forecast visibility. If I filed using only visibility criteria, I would have to carry enough gas to shoot the entire approach at my destination, go missed and divert to my alternate. If using ceiling and vis weather for filing, then we carry enough fuel to go to the IAF, fly past it and divert to the alternate and carry only enough fuel to shoot one approach. If I use ceiling and vis, I can show up to my IAF at the destination, and if the weather is above approach mins by an acceptable margin, I can roll the dice shoot the approach and know that I won't have to miss. If the weather is pretty close to mins, i.e. sky obscured and RVR less than a mile for an ILS, then maybe I should just suck it up and divert smartly before I commit to an approach that might end up in a miss and then trying to divert with not enough gas.

The High books will go away sometime this summer. It will be interesting to see if the Civilan thin paper books will include any of them. There are some to civil fields that are not that high. The Hi VOR RWY 3 to San Angelo for example has an IAF at only 12,000.

 

[STBY GAIN]

My understanding about why we have HI-IAPs is included in many of the previous replies, but here's my take. In the Viper, the map case is barely big enough to hold a full piddle pack, much less the entire Low-series pub set. We are required to carry the standard HI charts, IFR Sup, and FIH in there. It is also rather inaccessible in flight, or at least it takes some gymnastics to get back there. There is a little pocket on the other side of the 'pit that is much easier to reach, that is big enough for about 1 approach book. Conveniently, this one book holds just about all the approaches I could want to fly in my 1/3 of the country.

As far as the actual TACAN penetration goes, they are rarely flown other than for currency. What the previous poster, TweetDriver said about them, is spot on; it's a lot easier to divert from an IAF at 15,000 feet than from something a lot lower. The IAF's are usually a lot easier to get to from the enroute structure if you are comm-out, which is a big part of why the full procedure exists.

Finally, a large number of the low-book procedures include such funny maneuvers as procedure turns and procedure tracks and holding-in-lieu-of approaches. If I'm really comm-out, I'd rather penetrate off a TACAN from 15,000 feet than try to remember back to Tweets about which way to turn for a procedure turn (the last time most of us did that!)

As alluded to earlier, there is a note inside the front cover of the most recent IFR Sup; they are indeed consolidating HIs and LOs into a 24(?) volume set, with the HI charts having the black slashes on the borders. That's going to be a tight fit in the cockpit, I'll tell you that much. I see that lasting about 6 months.

 

[talondriver]

I think I'll just find a airfield VFR and report initial.

 

[JCJ]

two other things re DOD vs NACO plates

If you look at the NACO low altitude enroute IFR chart, you will notice that airports are listed in either blue, green or brown. the color is related to charted IAP's

blue - airport has at least one IAP published in the DOD plates (includes mil airports with IAP's published only in DOD plates as well as civil airports with approaches published in NACO and DOD plates)

green - airport has IAP published in civil NACO plates only

brown - airport has no published IAP's (may apply to civil or mil)



in small print at the top of the page of the IAP will be an abbreviation for the publishing agency - usually FAA for civil, USAF for USAF, USA for Army, USN for Navy & Marines