NAT-MNPS inflight contingency procedure
 

If an aircraft is not able to mantain is assigned level in the NAT MNPS area it should leave its assigned track turning 90° deg. L/R minimizing the rate of descent untill estabished 15 NM off track.
Once 15 NM parallel descent as soon as possible below FL 285 (MNPS lvl );
My question is: Wich is the correct course of action to initiate a diversion to the alternate? Can I start my diversion leaving FL 285, while increasing the speed ? or I am forced to go down to the 1 eng out level before doing so?

Hi.

My understanding is that you could set course to your alternate once you have descended below NAT airspace (ie. below FL285). I am not aware of any requirement to be level at your one engine-inoperative cruising FL.

First choice is to get on to ATC and get a clearance before leaving the 15M offset track, regardless of level. If you are unable to wait that long (can take 30 mins to get a new clearance!) then you should stabilise at a level between the normal levels, i.e. at a 500', before crossing other tracks whilst broadcasting on 121.5. Don't forget that there is other traffic not following the day's OTS, flying random routes and/or below MNPS airspace. Also don't forget that below MNPS is still class A controlled airspace, just with larger track separations because there is no requirement for approved nav kit.
Hope you never have to use it!:ok:

While on Nat Tracks, company ETOPS quiz asked 'How wide is a Nat Track'. Could not find the answer anywhere (or anyone who knows:confused:) and guessed at 20NM. Anyone got a link?

Enjoy all that lies before ye

;)

I have had to descend in MNPS airspace three times, once for a pressure door unlocked and twice due to engine shutdowns (aint't the military a wonderful training ground) and it was usually a non-event. Declare the Mayday, or otherwise, tell the radio operator (Gander or Shanwick) you have a problem and within a moment you will be speaking directly to an OAC controller who can make a traffic decision quickly. Once, it was "descend on track, at FL 280 or below proceed direct Gander, advise when level and direct CYQX." Another time, pressure door unsafe, it was "descend on track to FL100 and advise when able higher level." We could not then get above FL 290. The last time, the OAC was unable a clearance immediately, we offset, 30 nm at the time, and descended. Once level, with OEI, recleared onto the track coordinates to the landfall fix at the driftdown level.

Just take the time to get your drills done, advise the OAC what you need and it shouldn't be a problem. Now I operate on random routes above the track system, I think it is harder-the first imperative is to change the flight plan to the nearest track AND establish an offset prior to descending. A whole bunch more keystrokes. And I have had routes that cross three tracks, so at each significant fix, you have to have yet another track in mind for emergencies.

GF

H-1 - A useful doc I have not seen 'afore, but I cannot find the answer!:{

So - back to my query, to satisfy the CPD (Company Pedants Dept:)).

Anyone have the width of a Nat Track?

Distances Distances Distances
 

2 miles on SLOP
5 miles before NY are notified of a Lateral Deviation Event (ADS equiped)
10 miles Wx deviation before climb or descent
RNP 12.6 MNPS requirement
15 miles in flight contingency
25 miles definition of Gross Navigation Error
60 miles between tracks

I think the answer must be 0

Lateral separation

Below MNPS airspace 120nm
Between Usa/Canada/Bermuda 90nm
Betwen Iberia and Azores 90nm
BetweenIceland/ Scandinavia and UK 90nm

A/c MNPS compiant in MNPS Airspace 60nm

All from company docs.

Cheers

.or 2...or 5...or 10............................?

Galaxy Flyer wrote:

"tell the radio operator (Gander or Shanwick) you have a problem and within a moment you will be speaking directly to an OAC controller who can make a traffic decision quickly."

Very interesting and very useful info. I did not realize that a controller could chip in like that - I assume we are on HF here.

A Library of files for North Atlantic Flight Planning, that probably contains answers to most of the above, is here:

http://www.worldairops.com/NAT

The focus here is on providing Aircraft Operators, Pilots, and Dispatchers with a free centralised resource for North Atlantic flying.

BOAC
The minimum lateral separation for the North Atlantic Track system is one degree of latitude, so 60 NM.

galaxy flyer
Thanks for sharing your experiences.
Just curious here, what kind of 'C-5' do you fly now to be above the track system ?

Con - the query was the width, not the separation. Looking at Mr Ripley it could be anywhere between 20 and 50?

NAT Track width
 

BOAC,

I'll try and answer your question ... though this isn't gospel, but is formed from my previous experience as an ATCO.

The width of a NAT track is 0.01 nm. Its a conceptual width, because its not the same as an airway in the UK, with a width for example of 5nm, or 10nm.
A NAT Track is not an airway - its a line.

The intention, and hope, is that you fly that line as close to being on it as possible.

Because of weather, SLOP, In trail turbulence, Nav errors, and more, an aircraft will at times not fly on that line - and there are tolerances associated with the above (10nm, 2nm, 2nm, 25nm, etc.).


Hope that helps ...

Thanks, Shamrock - I'm familiar with the 'conceptual' width and we normally 'offset' 1 or 2nm - it was the actual width I was after, and Mr R's post is the closest I have got. This was prompted some time back when the spacing halved and it is often difficult to execute a 180 in 15nm. The suggestion (from the '15nm' parallel rule) would be that the tracks would be probably 20nm 'wide', I guess, giving a 5nm margin? Mr R's MPNS 12.6 nm limit makes it quite close!

Initial Action

11.3.2 The aircraft should leave its assigned route or track by initially turning at least 45° to the right or left whenever this is feasible. The direction of the turn should, where appropriate, be determined by the position of the aircraft relative to any organised route or track system (e.g. whether the aircraft is outside, at the edge of, or within the system). Other factors which may affect the direction of turn are: direction to an alternate airport, terrain clearance, levels allocated on adjacent routes or tracks and any known SLOP off sets adopted by other nearby traffic.
Subsequent Action

11.3.3 An aircraft that is able to maintain its assigned flight level, after deviating 10 NM from its original cleared track centerline and therefore clear of any potentially conflicting traffic above or below following the same track, should:

a) Climb or descend 1000 ft if above FL410

b) Climb or descend 500 ft when below FL410

c)Climb 1000 ft or descend 500 ft if at FL410
11.3.4 An aircraft that is unable to maintain its assigned flight level should, whenever possible,
d)initially minimize its rate of descent when leaving its original track centerline and then expedite descent to a
e)feasible flight level which differs from those normally used by 500 ft if below FL410 (or by 1000 ft if above
f) FL410

I never could quite understand the climb or descent 500ft if your able to maintain your FL.

If you can maintain your flight level why would you leave the track? If your diverting you would need to descend to below FL285 anyway, or am I missing something?

I understand that descending below FL285 will avoid other tracks but surely staying high as long as you can at +/-500ft would save on fuel and get the same result i.e avoid traffic?

If your ultimate strategy is to divert to an airfield `abeam` or an airfield `behind you` then you will have to leave the track centreline to ensure separation from other OTS traffic.
Because your eventual diversion route is not (yet) subject to a formal ATC clearance then changing level by +/- 500 ft (assuming you were cruising below FL410 and not thrust limited) will be necessary to give you some degree of vertical separation from other traffic.
You are NOT obliged to descend below FL285, even if diverting `across` the OTS (weather issues i.e. CB below you, or shortage of fuel?). You could divert from Track `D` to Keflavik maintaining FL355 if you wanted to (NAT doc 007 refers).
If your intention is to divert to an airfield ahead of you, then it may not be necessary to leave the NAT track in the first place. Because you are then complying with an existing oceanic clearance, if you still have sufficient thrust, no change in FL would be necessary.