Depressurization

[inducedrag]

I would like to know what DEPRESSURIZATION STRATEGY different airlines have when over flying Afghanistan high terrain and going towards China over flying Pakistan

[Jimmy Do Little]

I don't know about the routes that you mentioned, as I don't currently operate them. However, it probably involves a reroute (diversion point) which will keep you clear of the terrrain, and may involve having to do a bit of a 180 turn to join a lower level airway. We used to use a similar statagy between India and Singapore. I'll run it past the flight ops dispatchers tomorrow and see what they come up with.

[SNS3Guppy]

When flying over high terrain, one executes am emergency descent to a safe altitude such as the MEA for the route being flown or MSA, and continues until one can descend further, when able. If diversions are an option, then one diverts. They aren't always an option.

[Jimmy Do Little]

When flying over high terrain, one executes am emergency descent to a safe altitude such as the MEA That goes without saying. I assume that the poster was looking for a strategy pertaining to a specific route.

This would be similar to the terrain issue in the Contiguous 48 states - East to West. I can't recall the exact position, but there is a point - due to the Rocky Mountains - where "Drift Down / Depressurization" requires a 180 turn, and another point where continue forward is the only option.

The example I used - India / Singapore - involves a 180 turn back to a specific waypoint, then a low level airway around the terrain to a diversion alternate (Note: it's an ETOPS route). If I had the route manual in front of me, I could provide the points for better clarity, but I don't have it handy.

Nonetheless, I assume that this is the type of information he/she is looking for. Hopefully, the poster will confirm.

[SNS3Guppy]

This would be similar to the terrain issue in the Contiguous 48 states - East to West. I can't recall the exact position, but there is a point - due to the Rocky Mountains - where "Drift Down / Depressurization" requires a 180 turn, and another point where continue forward is the only option.

After many thousands of hours over (and among) the Rocky Mountains, I've never heard of, nor seen such a point. It doesn't exist. If one is at at low altitude in a performance-limited aircraft, one respects drainages...water flows down hill, and so do we. I've spent a lot of time at very low altitude in the mountains, and religiously adhere to this rule...because mountains can typically outclimb airplanes.

If one is at a higher altitude, one looks at the airports available if this is required, and goes to one of them. If one is close to the point of departure, one may turn back, and if one is in a better spot to continue to one's destination, one goes there.

The rocky mountains aren't all that high to begin with from a transport category perspective, as the highest point in the lower 48 states is only about 15,000' high. This is very high in for a non-transport category aircraft, but otherwise, there are generally plenty of options, and there is no point of no return when crossing the rocky's...and in fact, there are a number of places to go while one is over them.

The example I used - India / Singapore - involves a 180 turn back to a specific waypoint, then a low level airway around the terrain to a diversion alternate (Note: it's an ETOPS route). If I had the route manual in front of me, I could provide the points for better clarity, but I don't have it handy.


You're assuming this is necessary at all. One need not consider only terrain. Circumstances may be that, owing to terrain, distances, remoteness, fuel reserves, etc...one may not be able to descend. This is frequently a concern on an oceanic crossing...where can we go, and how low can we go and still have fuel to reach an alternate? While crossing high terrain, one may be confined to remaining at a higher altitude until past terrain, then descending at the MEA will allow, to reach a suitable destination.

This is one reason to always have a chart available. Engine fails here, we go there. Engine fails there, we go here. At any given time.

On oceanic trips we have equal time points and alternates applicable there-to, sometimes multiple ETP's between multiple alternates, which we know in advance and can recalculate given changes in winds aloft or routing. However, over shorter distances such as as higher terrain under discussion, we don't calculate that, and have no need to calculate that. If we need to remain at altitude for a given period, there's oxygen on board to do that, and we will, until the MSA or MEA or MOCA will allow us lower. In the meanwhile we'll be looking for a place to go, and once that is determined, we'll go there. Simple.

[tightcircuit]

To answer the question.

Airlines publish oxygen escape routes for significantly large areas of terrain that have safety altitudes above 10,000'. We don't fly over the Himalaya but on our network Iran and East Africa are areas where escape routes are needed. The Alps don't cover a sufficiently large area to require it.

TC

[Jimmy Do Little]

If one is close to the point of departure, one may turn back, and if one is in a better spot to continue to one's destination, one goes there.

JFK - LAX. 2475 NM sector - then suddenly depressurized - with substantially higher fuel consumption.... Which would you choose? Point of Departure, or Destination.

Or, is this going to get the whole Enroute Alternate thing started again?

there's oxygen on board to do that, and like fuel, it is NOT an infinate amount.


Normally I'm a fairly PC individual - allow everyone their opinion, etc, keeping my conclusions to myself, etc - but now breaking from that tradition.

I recall what the user "Rainboe" mentioned in another forum...

It's getting frightening to answer any queries here because there are always pedants who will prove your answer wrong for a type that is not even being asked about.

Guppy....I've gleamed very little from your various responses, except that you infer that you operate an "Oceanic..." capable aircraft "...within several feet of mountainous terrain..."

Not much more needs to be said!


Airlines publish oxygen escape routes for significantly large areas of terrain that have safety altitudes above 10,000'.

TC Correct! Thank you. Only leaves the fuel issue ... Where applicable.

[Rainboe]

The question goes a little deeper than simply depress over the Rockies or Alps. Nowhere has such expansive or high terrain as the Himalayas and Tien Shan mountains to the north. Quite fascinating to fly over there at 35,000' and see terrain so close! The problems involved there are that the terrain vastly exceeds 10,000' for such a large area you can get easily get caught exceeding the emergency oxygen supply for the passengers in a depress by having to remain above MSA which will greatly exceed 10,000'. This sort of terrain even a 747 cannot fly directly over, but it is acceptable to skirt the edges where you are still affected by high MSAs. The requirement on those particular legs where MSA is so high is you need to be able to reach a point and descend within your passenger oxygen limit, and if need be exit your route onto a lower MSA and descend. Those legs with the problem have escape routes published off the main route, and one must be aware which is nearest to get to and exit and descend within the time available. I recall this is a problem near Urumchi, north western China. It goes without saying that the exit routes should lead you to a suitable diversion route and airfield itself unaffected by oxygen requirements en route, as you will then be at a maximum of 10,000'.

It is advisable to warn the cabin crew when you are approaching such areas so they can be advised that any emergency descent will not get rid of the requirement to remain on oxygen.

[Jimmy Do Little]

FYI... (Not specific to the Oxygen issue, rather to Engine Out...)

VOLUME 4 AIRCRAFT EQUIPMENT AND OPERATIONAL AUTHORIZATIONS

OneHandbookNew.dot (http://fsims.faa.gov/wdocs/8900.1/v04%20ac%20equip%20&%20auth/chapter%2003/04_003_002.htm)



Engine-Out En route Limit. At an altitude of 1,000 feet above all obstacles within 10 miles of the course to be flown, the airplane must be able to climb at a rate specified as follows...

1) Airplanes certified under CAR 4B must be able to climb at .079-(.106/N) Vso2, expressed in feet per minute, where N is the number of engines. For a four-engine airplane with a stall speed of 100, the following formula applies: .079-(.106/4)1002 and .079-.0265 * 10,000 and .0525 * 10,000 = 525 FPM

2) Airplanes certified under CAR 4A must be able to maintain a rate of climb of .026Vso2 , expressed in feet per minute. For an airplane with a stall speed of 50, the following formula applies: .026*502 = 65 FPM

3) Instead of meeting the climb requirement, the operator may substitute an approved diversion.

The procedure must be approved by the POI and published in a CFM or a portion of the GOM.

When an operator proposes such a procedure, the airplane must be able to maintain an altitude of 2,000 feet above any obstacle within 5 miles of track after the assumed failure.

The rate of climb used to show this capability must be taken from the AFM and diminished by .079- [.106/N]Vso2 for CAR 4B airplanes or by .026 Vso for CAR 4A airplanes to compute a net gradient.

The operator’s proposed procedure must define a point at which the airplane is assumed to pass over the critical obstacle.

The operator’s procedure must define this point by means of an approved navigational fix.

The airplane must also be able to meet the required rate of climb at an altitude of 1,000 feet above the alternate airport. The procedure must provide an account of winds and temperatures forecast in the area. Fuel may be jettisoned to meet these requirements.

An en route alternate airport to which the airplane could divert, which meets the prescribed weather minimums, must be specified on the flight release when these procedures are used.

[inducedrag]

LIKE THIS FOR ALPS
EUROPEAN ALPS
DEPRESSURISATION STRATEGY
- The European Alps represent a critical area for all overflying
airplanes. They extend from South-Eastern France through
Switzerland, Austria and northern Italy. 24h airports are
depicted on the chart with dedicated ATIS frequencies.
- The Alps are considered to lie within a « box » bounded by
latitudes 43ºN and 48ºN and longitudes 005ºE and 014ºE.
- The « box » is divided into 5 sections of different colours,
each with a different procedure.

PROCEDURES
FL180
FL180
FL160
FL140
FL140
NORTH OF LATITUDE 46°N (pink)
- Descend to the North to FL180
- Track as required to LSZH, LFSB, LFST or LSGG
- ASAP, descend to the higher of Grid MORA and 10,000ft.
SOUTH OF LATITUDE 46°N (blue)
- Descend to the South to FL180
- Track as required to LFLL, LFMN, LIMC or LIMF
- ASAP, descend to the higher of Grid MORA and 10,000ft.
NORTH OF LATITUDE 46°N (salmon)
- Descend to the North to FL160
- Track as required to LSZH, EDDS, or EDDM
- ASAP, descend to the higher of Grid MORA and 10,000ft.
SOUTH OF LATITUDE 46°N (yellow)
- Descend to the South to FL160
- Track as required to LIMC, LIME, LIMF or LIRP
- ASAP, descend to the higher of Grid MORA and 10,000ft.
BETWEEN LONGITUDES 011°E & 014°E (green)
- Descend to the East, North or South to FL140
- Track as required to EDDM, LOWW, LIPZ or LJLJ
- ASAP, descend to the higher of Grid MORA and 10,000ft.

[Jimmy Do Little]

Exactly the same.

[inducedrag]

Any for overflying Afghanistan where some of the places MSA over 19000 Ft for over 200 miles

[Wizofoz]

Jimmys right on this one. Seems like Guppy is one of those guys that thinks the world extends from JFK to LAX....


We not only have depress escape routes for much of our network (which includes Himalays, Rockies, Alps, Iran (We're not over Afganistan again yet Induces- so the MSAs are only 17000'!) but we also have SE Driftdown procedures as some route have MSAs higher than out SE ceiling above a threshold weight.

there's oxygen on board to do that,

Yep, 21 mins worth for our pax in the 777 (14 in the A343:eek:) and a requirement to be below FL150 before it runs out.

[SNS3Guppy]

JFK - LAX. 2475 NM sector - then suddenly depressurized - with substantially higher fuel consumption.... Which would you choose? Point of Departure, or Destination.


Irrelevant, as ample alternate fields lie enroute, from chicago to Denver to Kansas City to Salt Lake City, etc. A hundred or more possibilities.

You suggested some mythical point of no return over the Rocky Mountains, as though they're some insurmountable barrier that can hardly be tamed. The truth is that from FL350, they're a little bump far below, and it's hardly an issue at all. As stated correctly before, if the departure is appropriate and nearby , then choose it. If one is close to the destination, then choose that. Otherwise, divert to any necessary, appropriate, available airfield. This is not rocket science. Closer to Kansas City? Go there. Closer to St. Louis? Go there. Closer to Chicago? Go there? Going south and Dallas is closer? Go there. No end of places to go. Boise? Sure. Albuquerque? Yep. Denver? You betcha.

Do any of these need to be previously "declared" alternates or part of the flight plan? Of course not. One diverts as required. Does one plan out each of these fields as a diversionary alternate? No, of course not.

Does one plan a series of diversionary alternates when crossing the rocky mountains? Of course not.

When overflying The Himalayas? Not necessary. Are we going to drop down, go around this mountain and then that, then connect with a lower airway and follow that? Doubtful. Point for the destination, notify ATC (such as it may be in that part of the world), and go in that direction, taking lower when able. Again, not rocket science.

and like fuel, it is NOT an infinate amount.


It doesn't need to be.

Guppy....I've gleamed very little from your various responses, except that you infer that you operate an "Oceanic..." capable aircraft "...within several feet of mountainous terrain..."


Actually no, I didn't say that. Your reading comprehension skills severely lack, but given your disjointed posting and your lack of understanding of your topic material, this doesn't come as much of a surprise.

One of my jobs (I do several) involves flying airplanes, some large some small, very close to terrain while engaging in wildland firefighting. Another job involves flying aircraft globally, including frequent oceanic crossings. These represent much greater distances with far fewer alternates, and are more critical and more significant than crossing a mountain range such as the alps, the himalayas, or the rockies...because one can't descend much due to fuel burn.

We never calculate equal time points with diversionary paths for routings over some of the areas discussed (Afghanistan, etc), because it's not necessary. There are options. Again, as you have trouble keeping track...one does NOT need to always consider the departure or destination, and there are generally plenty of alternate options enroute, even in remote parts of the world, should the need be. The only time this is not the case is during times of widespread weather (such as a cyclone), or on extended oceanic legs (when we do plan for alternate diversions...and in fact plan several types of alternate diversions, including depressurization).

[Wizofoz]

Point for the destination, notify ATC (such as it may be in that part of the world), and go in that direction, taking lower when able. Again, not rocket science.


...And run out of oxygen, letting many of the passengers DIE in the process or, in the event of an engine failure, drift gently into the terrain killing EVERYONE.

My ONLY job is flying aeroplanes, and I do so such that either a depressurisation or engine failure will not end my life or anyone elses.

You are fighting above your weight here Guppy- commercial operations over that sort of terrain REQUIRE stratergies to ensure saftey.

You assume that because it is outside you experience, it does not exist.

You are, quite simply, wrong.

[Rainboe]

Does one plan a series of diversionary alternates when crossing the rocky mountains? Of course not.
When overflying The Himalayas? Not necessary.
As I said, the Himalayas/Tien Shan mountains are far more extensive and much higher than you expect. You can't just turn off the airway and descend (and lose your MSA protection). Escape routes towards nominated alternates are planned from waypoints en route leading you to lower MSAs. These mountains are in a very different league compared with what we know!

[PT6A]

Middle East Restricted Critical Terrain Routes
General
Because of the sensitivity of relations between several Middle Eastern countries
and the United States, Restricted Critical Terrain Routes have been developed.
These special routes to be used in the event of cabin depressurization will enable
diversion to suitable airports outside of these areas, regardless of where the loss
of pressurization occurs.
Supplemental Oxygen Requirements
Supplemental oxygen bottles are used on these routes , to comply with the FAR
requiring oxygen for 10% of the passengers for extended flight between 10,000
feet and 14,000 feet. Maintenance is responsible for boarding the necessary
oxygen.
Terrain Avoidance Waypoints
NOTE: The highest terrain within 50 miles along the Iranian routes is 18,600 feet.
Driftdown altitude at 1EO cruise speed will exceed the highest terrain.
Six FMS waypoints are being used to assist pilots in circumnavigating several high
mountain peaks in eastern Turkey and Iran. The waypoints are described in the
route descriptions on each Restricted Critical Terrain Route Procedures chart.
The mountains are located in the following positions and elevations:
• Turkey - N38°55 E042°50 (13,314'), south of R660 between ERZ / TBZ
• Iran - N31°36 E054°03 (13,304'), on G663 between YZD / SYZ
• Iran - N30°47 E052°45 (12,936'), east of R659 between ISN / SYZ
The waypoints have been created to provide at least 20 NM horizontal clearance
from these mountains. If turns are involved, a 10 NM turning radius has been
incorporated. Examples are YZD32 and YZD41 in Central Iran.
Additionally, nine other waypoints have been created (and shown on the
Restricted Critical Terrain Route Procedures charts) where a descent from FL 140
to FL 100 may be safely made in the following areas:
• Turkey, on a westerly diversion to Ankara (LTAC) or Diyarbakir (LTCC).
• Iran, on a southerly diversion to Dhahran (DHA/OEDR), Bahrain (BAH/OBBI),
Doha (DOH/OTBD), or Dubai (DXB/OMDB).

In addition to the major mountain peaks listed above, other mountains that impact
a potential diversion have been printed on the Restricted Critical Terrain Route
Procedures charts. They are shown because a turn, if required, must be made in
a specific direction relative to the airway. A summary of these mountain peaks is:
• UG8 / G208 - between SRT and UMH. Several high peaks up to 13, 556’ lie
within 15 NM S of the airway.
• UA4 - between ERZ and VAN. A 13,314’ peak is 26 NM south of the airway,
approximately 102 NM SE of ERZ.
• R660 - between ERZ and TBZ. This same peak is 5 NM northeast of the airway,
approximately 36 NM NW of VAN.
• R660 - between TBZ and RST. A 15,785' peak is 29 NM north of the airway,
approximately 70 NM E of TBZ.
• R660 - between TBZ and RST. A 12, 163' peak is 27 NM south of the airway,
approximately 30 NM SE of TBZ.
• G208 - between UMH and ZAJ. This same peak is 27 NM north of the airway,
approximately 68 NM ENE of UMH.
• R654 - between SV and ISN. A 12,779' peak is 20 NM NE of the airway,
approximately 45 NM N of ISN.
• R654 / G452 - within 50 NM E and SE of KER. Several high peaks up to 14,650'
lie within 20 NM of both airways.
• W2 - between ZAH and LOXOL. A 12,930' peak is 17 NM E of the airway,
approximately 54 NM S of ZAH.



I have charts covering the route with escape routes... but not sure how to upload them onto the site.

[SNS3Guppy]

...And run out of oxygen, letting many of the passengers DIE in the process or, in the event of an engine failure, drift gently into the terrain killing EVERYONE.


Hardly.

You are fighting above your weight here Guppy- commercial operations over that sort of terrain REQUIRE stratergies to ensure saftey.

You assume that because it is outside you experience, it does not exist.



Whereas I operate in and out of many of the locations under discussion...including afghanistan, Iraq, and other locations throughout the region, you're wrong, of course. But thank you for your insight.

Escape routes towards nominated alternates are planned from waypoints en route leading you to lower MSAs.


Not in the operation for which I fly.

[Jimmy Do Little]

Actually no, I didn't say that. Listen Jack***, you did..in several forums! In fact, you said it AGAIN in this forum ...

One of my jobs (I do several) involves flying airplanes, some large some small, very close to terrain while engaging in wildland firefighting. Another job involves flying aircraft globally, including frequent oceanic crossings.


Not in the operation for which I fly. Exactly! Most of the posts here involve some level of Airline operations, whether they be major or regional. This post most certainly did!

Your reading comprehension skills severely lack but those skills seem to have been good enough to pick up on, and question, your BS.

Throughout ALL of your previous postings in other forums - in addition to this forum - you use statements like.... "...one must consider...", "...one must always...." the himalayas, or the rockies...because one can't descend much due to fuel burn. ...as you have trouble keeping track...one does NOT need to always consider the departure or destination, ...and if one is in a better spot to continue to one's destination...are a number of places to go while one is over them

"dependent use of third person".... a behavior known in Psychology circles as a classic sign of a BullS**t artist.


your lack of understanding of your topic material There is NOT one person here who has agreed with you! In fact, most everyone else has PROVEN that... You are, quite simply, wrong.


Giving the benefit of doubt that there is an element of truth in your - somwhat expansive claims of experience - I'd be rather surprised if even "Dyncorp" allowed their aircraft to be operated in the manner your described. BTW...is Dan Bannister still in charge over there?



..

[411A]

After many thousands of hours over (and among) the Rocky Mountains, I've never heard of, nor seen such a point. It doesn't exist
Hmmm, I suppose that one company I worked for, long ago, flying a Convair 440 over many routes that included the Rocky mountains, must have gotten their procedures all wrong...then.:rolleyes:
Not only that, but the FAA must have gotten it all wrong when they officially approved these company procedures, for these particular Rocky mountain routes.

Me thinks Guppy is just a tad misinformed.:}

[Jimmy Do Little]

Me thinks Guppy is just a tad misinformed

he's had too much time without enough Oxygen!

[SNS3Guppy]

Little Jimmy (et al),

I don't and have not presumed to tell you how others do, or ought to operate, but how my own employer operates, and no, I'm not misinformed. Such charts and such planning are not a part of our operation, and we do work extensively throughout that region. In fact, I'm there now.

you did..in several forums! In fact, you said it AGAIN in this forum ...



Actually...I did not. You simply can't read.

And no...I don't fly for dyncorp. You appear to have invented this in your own little jimmy mind.

Are you able, incidentally, to post without name calling?

[Wizofoz]

I don't and have not presumed to tell you how others do, or ought to operate

Oh really????:-

Does one plan a series of diversionary alternates when crossing the rocky mountains? Of course not.

When overflying The Himalayas? Not necessary. Are we going to drop down, go around this mountain and then that, then connect with a lower airway and follow that? Doubtful. Point for the destination, notify ATC (such as it may be in that part of the world), and go in that direction, taking lower when able. Again, not rocket science.


There was no "Well this is OUR procedure"- Sounds more like "Listen carfully, Sonny,This is how it's done by us professtionals":rolleyes:


Such charts and such planning are not a part of our operation, and we do work extensively throughout that region.

All well and good, SN4- but you did not say "MY operation does not require such things", but the they were UNNECESSARY- implying NO operation required them.

In this you were, as I said, quite simply wrong. It is implicit in the regulations I and most Airlines operate under that a proven procedure be in place to 1) Ensure the cabin is below FL150 before the Pax O2 runs out and 2) Terrain avoidance is guaranteed in the event of an engine failure.

How long does your PAX O2 last (assuming you carry pax, and if you don't, how can you possibly feel justified commenting on this subject!!) ? Are you SURE you are ALWAYS able to descend sufficiently quickly to not run out?On what basis do you have that surety? Is your SE ceiling ALWAYS higher than you MSA? If not, fine! Some operations except higher risks than others. Ours don't, and REQUIRE DARD procedures to be published and adhered to.

To suggest such things are unnecessary because you don't use then is either arrogant, ignorant or both.

[C-N]

SNS3Guppy,
"...one does NOT need to always consider the departure or destination, and there are generally plenty of alternate options enroute, even in remote parts of the world, should the need be. The only time this is not the case is during times of widespread weather (such as a cyclone), or on extended oceanic legs (when we do plan for alternate diversions..."

There are only 02 AWY connecting Lahore FIR (OPLR) and Urumchi FIR (ZWUQ), B215 and W112 both originates from PURPA intersection. Unlike the states, I'm afraid there are not much ENR ALT APT on that part of the planet, only 1 or 2.

[Jimmy Do Little]

Finally said something that I can't argue with....

This is how it's done by us professtionals Assuming of course that you meant PROFESSIONALS.

Interesting note though.....In fact, I'm there now

I'm not about to tell you where I am now, but whereever it is - describing it - I would be HERE now. Later, I may go somewhere else, but then I will be THERE. I simply can not - in my world - BE..THERE..NOW

Me thinks you're up to your BS again.



Enough is enough. This forum's usefulness has run out.

[Rainboe]

Chaps, it would be far better to stick to discussing the question and what our experiences of it are. There has been a dreadful trend in Pprune later of analysing everything down to the minutest detail to find opposite meanings and prove any answer, even my 'black is black- no it's not, it can be white!' remark, is incorrect in certain circumstances! Look at the icing question, and how my answer from Boeing manuals is dissected and torn apart! There trend is growing to personally attack and insult posters rather than play the ball.

All it is going to take us to is people who know refusing to get involved in answering queries because they know someone will try and demolish them. Let's just play the question, not the player.

[Old Smokey]

I'm in complete agreement with Rainboe, it is "far better to stick to discussing the question and what our experiences of it are".

I regularly fly the route mentioned in the original question, i.e. crossing Afghanistan / Pakistan.

Extended flight well above 10,000 feet is required, thus requiring an en-route Critical Point, with, as typical of any CP, onwards flight at or after the CP, and return if before.

For the route mentioned, if flying in a South-Easterly direction, return is made to Ashgabat UTAA (Turkmenistan) for depressurisation before the CP, or onwards flight to Lahore OPLA or Karachi OPKC if depressurisation at or after the CP.

Such flight requires carriage of considerably more oxygen than routinely required for "normal" depressurisation, and only about 50% of our aircraft carry the considerably increased (gaseous) oxygen supply.

For our entire global network, depressurisation strategies have been worked out, and routinely carried on all flights in paper form and the EFB.

Time gentleman please! Slanging match over..... nobody won, as usual.

Regards,

Old Smokey