Use of MSA during approach

[Panama Jack]

In the United States, the Minimum Sector Altitude (25 miles) that is displayed on your approach plate and provides 1000 foot terrain clearance can only be used in the event of an emergency. In Canada, on the other hand, it may be used as a minimum altitude at any time and pilots regularly do so during their transition to the approach. I am wondering what the ICAO norm is-- what is permissable when flying overseas? Can anybody cite their source?

[ExcessData]

Hi Panama

In Oz we use the 25nm MSA just as the Canadians do. Provided we can positively fix ourselves within 25nm of the aid around which it's based, we can use the lower of the route LSALT (assuming we remain on track) or the MSA as required.

Cheers, ED

[Crossunder]

In Scandinavia (and most of Europe), the MSA can be used any time. New Pans Ops is the doc. and it says nothing about MSA being "an emergency altitude only".

[Panama Jack]

Excellent, :}

Thanks to those of you who have replied. Regarding the PANS-OPS document, is this a newer issue (I had one a few years ago)? Do you know if the PANS-OPS can be viewed on the internet? I seem to remember that there were a few volumes of the PANS-OPS-- which one is it.

PJ

[OzExpat]

Pans Ops is just one document, but in two volumes. The Doc nr is 8168-OPS/611. Volume 1 is for pilots and Vol 2 is for procedure designers. I've been using Vol 2 for many years and am yet to come across any reference to an "emergency altitude". However, I hasten to add, I've never actually gone looking for it.

The terrain clearance concepts used in MSA design are the same as for the Initial Approach segment. To me, this suggests that the MSA is not regarded as an emergency altitude. Some countries may require such a limitation due to the possibility of navaid reception problems.

Hope this helps.

[Panama Jack]

This is indeed the concern of the FAA-- who says that it is for emergency use only since they cannot guarantee navaid reception.

[GlueBall]

It may also be described as Minimum Sector Altitude. The MSA value is supplied by the respective controlling authority, and at some airports the "25NM" standard differs.

[Panama Jack]

So I guess the question becomes-- you are flying into <insert country name here> tomorrow. Can you use the MSA as a minimum altitude on your transition? Oh, forgot to mention that the information does not seem to be as widely published and available as say, in the USA, Canada, or Australia, and you are in a non-radar, uncontrolled airspace environment.

[OzExpat]

The problem that you've suggested is too broad for a specific answer because there's a risk that some countries may have a very different idea about the use of the MSA. I offer the following as general advice - it is also the way that I would approach such a problem.

Many companies produce their own Route Intelligence Manual, in which the applicable differences in rules and procedures are explained, for all the places they operate to. Sometimes, they get Jeppesen or some other company to compile and update this manual for them. If your company doesn't have such a document, your only recourse is likely to be the Jepp Chart Manual for the particular country. There might be some info in there to help you out.

If not, then either you need to contact the regulatory agency for the particular country for the info, or decide not to use the MSA unless the weather is relatively good. Clearly, this requires a fair amount of advance planning, but you owe that to your passengers anyway.

Sorry that I can't be more specific. Perhaps someone else has a better idea?

[LEM]

Interesting and useful thread.
I must admit I'm not sure if in Europe the MSA (Minimum Safe Altitude when the same altitude applies all around, or Minimum Sector Altitude when the 25NM circle is divided in various sectors with different altitudes) has to be treated like in the US.
Yes I recall overseas the MSA can only be used in an emergency since it doesn't guarantee the reception of navaids.
If it is true that in Europe the MSA can be used routinely, my question is: Why bother to establish higher altitudes and longer procedures to fly the approach when everything could be much simpler using the MSA?

Most of the approach altitudes are higher than the MSA value.
Why?
If you can, please have a look at LICC (Catania, Italy) ILS DME-Papa Rwy 08 (6 AUG 99).
That's a good example.
Why must one descend 7000ft in the arc, and then descend 5800ft in the AMAKA racetrack, when he could do a straight-in if using the MSA?
The first time I went there I did so, but then we realised the guy behind was really upset, and also ATC had expected me to do a straight-in (but didn't complain openly).

I suspect there's some confusion in this matter, and pilots decide by themselves whether they can use MSA or not, knowing with good common sense they won't loose reception of the navaids.

But is this academically correct?

I would appreciate very much a clear answer to that, to know if that day in Catania the AZ captain behind me was right to complain.
Thanks :O :hmm: :E

[Panama Jack]

Unfortunately I have no European Jepps, so I can't take a look at your airport although it would have been interesting to me.

In the area that I am refering to (Middle East) the terrain around most of the airports is flat as a pancake so I don't consider it much of a safety issue even when in the soup.

The thing is that some approach transitions are very high right to the approach aid for the full approach (requiring then about 4000 feet in altitude loss within 10 miles). Another scenario is when (using GPS) being cleared direct to the Intermediate Fix, in other words, off any published transition and not requiring a procedure turn.

[LEM]

Well, clearly this debate is centered on the navaid reception capability, not on the protection from high terrain.

MSA protects for sure against obstacles.
But we are wondering if it can be used in a normal approach because of the reception issue.

[Crossunder]

If there's a problem with nav aid reception, the STAR altitudes wil be marked as MRA. In Europe I've never heard of Minimum Safe Altitude as a general term, and MSA = Minimum Sector Altitude. The others safe altitudes are called MOCA/MORA/MRA (as I suppose they are overseas as well?).
As for LICC, I suppose nav aid reception could be a problem, but you'd still be safe above MSA... Other factors could be avoidance of GPWS, noise abatement, turbulence etc. Also, Pans OPS specifies maximum track change without addnl guidance (70deg if I remember correctly?) allowed when going from the initial segment to the intermediate/final approach segment. A DME arc with a lead-in radial/QDM (R267@LICC) will help get you established on the inbound track without having to go via some reversal procedure (procedure turn, racetrack etc). You'd then need a MRA in order to follow the arc. You'll also avoid having a lot of aircraft buzzing around, making their own arrival routes as they go along (ATC nighmare). Very often ATC will give you "When ready, direct..." during climbout. As you pass through MSA it would be safe to turn on course. You'll not be needing any nav aids, only GPS, and it's not an emergency. When we fly FMS/overlay & GPS standalone approaches, we have three entry-fixes, each with their own MSA, and so the "old" MSA will not be relevant. Much easier, as you won't need any lead-in radials, fixes, racetracs aso.
As for LICC I don't know why you can't go below 7000ft. Etna seems to be out of the way, and you can go down to 6.000ft if going directly to the VOR. Beats me...
JAR OPS requires an operator to use published instrument procedures, and the procedures don't allow "own navigation onto the ILS" unless it's on ATC vectors.

[OzExpat]

I don't have the LICC chart either, so can't offer anything further than has already been suggested. I think that the minimum track length issue is a real possibility, but it might also have something to do with separation between inbound and outbound traffic?

The thing is that some approach transitions are very high right to the approach aid for the full approach (requiring then about 4000 feet in altitude loss within 10 miles). Another scenario is when (using GPS) being cleared direct to the Intermediate Fix, in other words, off any published transition and not requiring a procedure turn.
If your talking about "The Sandpit", PJ, there may be another reason for this situation. It could be that the very nature of the ground around the navaid sites attenuates navaid signals, thereby effectively reducing reliable range. This would force the need to ensure that the aircraft can receive the navaid reliably before allowing descent.

And, of course, as stated above, it might also be necessary to keep arriving aircraft high so that departures can be separated procedurally. That' always a bonus to ATC if they don't have Radar, or if it's a bit unreliable.

[wellthis]

MSA or Minimum Sector Altitude should have the same meaning everywhere I believe as it is minimum obstacle (not terrain) clearance. You'll probably find that in the areas that it is used in transition are more remote areas that don't have an IF or IAF. You might also recall that you could sometimes be below this altitude on radar vectors, in which case if one loses radio contact, one will immediately have to climb to MSA.

You should have reception of the navaid to which you are tracking (in the center of the circle), but not necessarily to all other required for shooting the approach. Therefore, if no transition and no vectors, you'll have to fly to the fix in the center (normally the beacon) do the PT, and the rest of the approach.

However, you'll find that in some cases MSA is below PT or some other areas of the approach, in which case one would be wise to maintain the higher altitude (probably for reception, noise abatement,...). Keep in mind that MSA is just that and only keeps you away from obstacles and more importantly is not for approach only as it CAN ALSO BE USED FOR DEPARTURE. As a matter of fact, folks often include that in DEP briefings for emergency purposes. Hope this helps.

[Oceanic]

'' You might also recall that you could sometimes be below this altitude on radar vectors''

Bearing in mind minimum vectoring altitude is often below MSA,what comfort does that give when one is at the mercy of (sometimes dodgy) ATC and being vectored to an unfamiliar airport in night IMC in areas of terrain? Does that not abrogate responsibility of the pilot and place it in the hands of the controller?

[OzExpat]

wellthis...

MSA or Minimum Sector Altitude should have the same meaning everywhere I believe as it is minimum obstacle (not terrain) clearance.
Well I gotta say that, after 16 and a bit years of Pans Ops instrument procedure design experience, this statement has confused me. What is the difference between having obstacle clearance and having terrain clearance? The way I read Doc 8168, there's no difference at all, so some clarification would be most enlightening.


You'll probably find that in the areas that it is used in transition are more remote areas that don't have an IF or IAF.
Since when does an instrument approach procedure not have an IAF? I'll admit that I've only ever looked at Pans Ops and TERPs procedures, but they've all identified an IAF.


Oceanic... you make a good point about vectoring altitudes provided by ATS. Some regulators produce a chart that is called a Radar Terrain Clearance Chart, or something similar. This chart does not consider airspace boundaries and might not even take account of Restricted or Prohibited Areas, but it will keep you out of the weeds. The intention is, of course, to give pilots some power over their destiny while being vectored.

There is another type of chart that is sometimes produced, called a Radar Vector Chart. This is the one that ATC are supposed to use as it accounts for all airspace boundaries as well as terrain, err, excuse me, obstacles...

The problem is, of course, that it can be easy for a pilot to loose the plot if ATC vectors you off the direct track to the bit in the middle. Well, no system is perfect, but at least it's something that's better than nothing.


Does that not abrogate responsibility of the pilot and place it in the hands of the controller?
Inevitably, this will be the case. There's not a lot that a pilot can do in such circumstances. I'm aware of some places that have had a pretty poor track record with radar vectoring and all I can say is that, if you're unhappy about accepting vectors, it's better to speak up and request an alternative clearance.

There's problems with that too of course but, like I said before, no system is perfect. I daresay that your company's Route Manual warns you about such places, so it may also contain some other useful ways to avoid a radar vector.

[wellthis]

As for the difference between MVA & MSA, it might be due to reception of the navaid in the center of the MSA circle, which you won't need since you're on vectors, or it could be due to a localized obstacle in the other end of the circle and you're being vectored in the opposite direction, (possibly slightly below MSA, for short period of time and in VMC) to expedite traffic. MVA is also highly regulated and you often hear the ATC saying that is the lowest they can take you and is not based on how they feel that day. And yes I believe they are responsible for airplane's safety as well.

As for the definition of obstacle, I thought it was rather clear that it includes buildings, antennae, terrain, etc.

As for IF/IAF, many less busy airports (especially higher latitudes) don't have them and pilots use MSA as a guidline, but if there is a higher altitude later in the approach on DME arc, PT, etc. (most likely for reception), they stay higher until that point. Also, many busy airports with no STAR and just profile descent, not to mention many busy US airports, don't have them either and rely on RV for transition. If one were to lose the radio on the approach, one could get very creative on how to continue! (as you know IF/IAF are for 'airborne navigation' transition from enroute to approach-ie no vectors).

The thing with MSA to keep in mind is that it does not guarantee reception of all navaids required for the approach. It is not only for approach anyway, as half the time it could be used while tracking away from the center of the circle on departure. Hope this helps.

[ooizcalling]

There was an earlier post on this subject,

http://www.pprune.org/forums/showthread.php?threadid=81641

We fly in Europe using Jepp charts which do have the 'Emergency Use Only' qualification. Where do you stand then if Pan Ops has no requirements but the charts you're using do ?

A question for the 'Legal Eagles' ?

[OzExpat]

ooizcalling... As a purely practical suggestion, you should probably consult your company's T+C folks to find out what your company policy is. If there's no specific info in your company's Route Manual and if your company has approved the use of Jepp Charts by all company pilots, I'd say that you are bound to abide by all the info on the relevant Jepp chart.

If that chart happens to state "Emergency Use Only" for the 25NM MSA then that's what you're stuck with. You'd be hard-pressed to justify any other interpretation if you ever had to explain your actions in front of "the beak"...