NAT/HLA Contingency

[perhaps]

Hi All,

Following (hypothetical) scenario:

In NAT/HLA airspace, random route, CPDLC.... etc...

Something happens in flight which requires you to divert, let's say a medical thing... basically something where you can maintain altitude.
Now the hypothetical part, you are unable to get a re-clearance by ATC ... it takes too long... you decide to use the contingency procedure...

Am I right in saying that you go offset by 5NM, climb/descent 500ft - then you are allowed to immediately divert at this "new" altitude to the direction of your diversion airfield.
As you can maintain altitude, a descent below FL290 is nor required nor obliged, and all in accordance to the contingency procedure ?

A few times I have the "discussion" that this diversion turn can only be made, when offset by 5NM, 500ft vertical offset and below FL290... which I believe is only correct if you can not maintain altitude.

Looking forward to your comments.

[Jonty]

This is taken from our manual

“Establish on a parallel offset track by 5 nm, then either:

Establish a 500 ft vertical deviation and proceed as required, or

Descend below FL290 and establish a 500 ft vertical deviation from standard levels and proceed as required until revised clearance is received.”

[Jonty]

And here’s ICAO Doc 4444
Actions to be Taken once Offset from Track

The pilot’s judgement of the situation and the need to ensure the safety of the aircraft will determine the actions outlined to be taken. Factors for the pilot to consider when deviating from the cleared track or ATS route or level without an ATC clearance include, but are not limited to:
a)operation within a parallel track system;b)the potential for User Preferred Routes (UPRs) parallel to the aircraft’s track or route;c)the nature of the contingency (e.g. aircraft system malfunction) and;d)weather factors (e.g. convective weather at lower flight levels).If possible maintain the assigned flight level until established on the 9.3km (5NM) parallel, same direction track or ATS route offset. If unable, initially minimize the rate of descent to the extent that is operationally feasible.

Once established on a parallel, same direction track or route offset by 9.3km (5NM), either:
a)descend below FL290, and establish a 150m (500ft) vertical offset from those flight levels normally used, and proceed as required by the operational situation or if an ATC clearance has been obtained, in accordance with the clearance; or Note: Descent below FL290 is considered particularly applicable to operations where there is a predominant traffic flow (e.g. east-west) or parallel track system where the aircraft’s diversion path will likely cross adjacent tracks or ATS routes. A descent below FL290 can decrease the likelihood of conflict with other aircraft, ACAS RA events and delays in obtaining a revised ATC clearance. b)establish a 150m (500ft) vertical offset (or 300m (1000ft) vertical offset if above FL410) from those flight levels normally used, and proceed as required by the operational situation, or if an ATC clearance has been obtained, proceed in accordance with the clearance. Note: Altimetry System Errors (ASE) may result in less than 150m (500ft) vertical spacing (less than 300m (1000ft) above FL410) when the above contingency procedure is applied

[perhaps]

Thanks for your reply.

I am aware of the contingencies you stated, so we are on the same page… but…

the discussion starts with the “interpretation” of when established of track, descend 500ft… and proceed as required until…

in my opinion, you theoretically could then immediately turn towards your diversion aerodrome, without descending below FL290.
other colleagues have a different opinion and say for diversion you need to descend below before you make that turn.

[Chesty Morgan]

in my opinion, you theoretically could then immediately turn towards your diversion aerodrome, without descending below FL290.
Straight back through the NATHLA you're trying to avoid?

[perhaps]

Trying to avoid is not the case… you need to divert… and it’s a theoretical approach to the phrase “proceed as required”:

“Establish on a parallel offset track by 5 nm, then either:

Establish a 500 ft vertical deviation and proceed as required, or
descend ……. and proceed as required.


If you are able to maintain altitude, but require an immediate diversion… my interpretation is that you can…. According the above (in contingency of course) ….

Or am I wrong …

[Jonty]

other colleagues have a different opinion and say for diversion you need to descend below before you make that turn.

where does it say that?

[BleedingOn]

I agree, you can offset, change by 500ft and then divert. But I would add that your SA for this needs to question if doing so becomes a greater threat (ie crossing a load of busy tracks) than descending (or in your hypothetical situation, climbing) out of HLA before diverting.

You’re diverting so maintaining a cruise altitude becomes less of a priority. You may want to jettison (again at 500 feet spacing across tracks? Perhaps not ideal). At FL 285 your TAS will still be pretty decent but GS may also be a consideration.

Essentially this becomes an SA and threat analysis decision, but the regs do allow it

[perhaps]

All,

thanks for your reply…

BleedingOn, I fully agree… it will be a decision of the day, taking all factors, of which SA is a big one (random or tracks,…) into consideration.

the question itself was a theoretical understanding of the rule itself.
but we are on the same page.

thanks !

[Fursty Ferret]

All,

thanks for your reply…

BleedingOn, I fully agree… it will be a decision of the day, taking all factors, of which SA is a big one (random or tracks,…) into consideration.

the question itself was a theoretical understanding of the rule itself.
but we are on the same page.

thanks !

I would descend below FL290. But once out of the NAT HLA nothing stops you getting a clearance to climb back to a sensible cruise altitude if you're facing a three hour trek to your diversion airfield.

[deltahotel]

https://www.icao.int/EURNAT/EUR%20and%20NAT%20Documents/NAT%20Documents/NAT%20Documents/NAT%20Doc%20007/NAT%20Doc%20007%20Ed%20V.2023-1_eff%20Jan2023.pdf

I find this graphic from Doc 007 very helpful, both for me and when teaching this. Hoping the link works!

So, the link to the page didn't work, but the graphic is on page 101!

hth

[BBK]

Perhaps

It’s good to ask hypothetical questions and it shows you’re considering possible scenarios. However, on this occasion I think it would be misguided NOT to descend below the tracks. Why take the risk? It will only take a few minutes to do so then you’re clear of the tracks. In reality you might get a reclearance very quickly anyway at the level you request.

I was speaking with a colleague who had an inflight shutdown and diverted while in Gander airspace. He said they came back with a clearance very quickly. Hope that helps.