Terrain

[Little Friend]

Some help please.

Thinking more european ATC-but when is ATC responsible for terrain clearance and when not.

Obvious phrases like "do you have ground contact" and "according to your minima" but is there a more subtle trap waiting for the unwary.

[Spitoon]

ATC has responsibility for ensuring terrain clearance only when aircraft are being vectored.

I think this is a pretty universal rule and originates from ICAO.

[whowhenwhy]

As far as I'm aware, the only time an ATCO is responsible for terrain separation is under Radar Control. Under any other type of service, it is ultimately the pilot's responsibility.

ATSUs will set a level or levels below which RAS will be terminated or not offered.

Under RIS, radar vectors will not be supplied below the ASA/MSFL except under strict conditions such as, actual emergencies, short pattern circuits or radar to visual approaches inside 10nms from the airfield. Although these are military guidelines, I would imagine the civil ones are much the same??? Anyone else able to shed any light?

[Little Friend]

It was the radar control issue which promted my post.

The first reply gets to the point that only under vectors. Expanding on that if you are following a SID/STAR and are given a "direct to" does that mean that you are(flightcrew) soley responsible for terrain sep.

Also when on vectors to an app. you are sometimes given a "direct to" and told to contact XYZ. Is this a handover of terrain responsiblity to the flightcrew if contact is not made on the next freq?

[bookworm]

Expanding on that if you are following a SID/STAR and are given a "direct to" does that mean that you are(flightcrew) soley responsible for terrain sep.

No. In the UK...

13.1 Controllers are to ensure that levels assigned to:
a) IFR flights in receipt of a radar control service
b) flights in receipt of a radar advisory service and
c) flights in receipt of a radar information service and receiving vectors;
provide adequate terrain clearance...

Unless the "direct to" takes you outside controlled airspace, the level assigned in the ATC clearance must ensure terrain clearance.

[Spitoon]

It's an interesting - but gray - area. ICAO PANS-ATM says:
8.6.5.2 When vectoring an IFR flight, the radar controller shall issue clearances such that the prescribed obstacle clearance will exist at all times until the aircraft reaches the point where the pilot will resume own navigation. When necessary, the minimum radar vectoring altitude shall include a correction for low temperature effect.

It also defines Radar vectoring as the provision of navigational guidance to aircraft in the form of specific headings, based on the use of radar.

So, according to the strict definition used by ICAO, I'm not sure that a 'direct to' clearance is vectoring.

As bookworm says, in the UK we have slightly more defined rules but remember that in the UK many more IFR flights take place outside controlled airspace than (I think) in other States and, as far as I recall, the radar advisory and radar information services, certainly in the way we do them in the UK, are pretty much unique to the UK. But, of course, we only need these services because we don't have controlled airspace protecting all IFR routes etc.

[bookworm]

So, according to the strict definition used by ICAO, I'm not sure that a 'direct to' clearance is vectoring.

I agree, and it's a slightly worrying ambiguity of responsibility.

I remember chatting with a procedure designer after the Cali crash (http://aviation-safety.net/database/record.php?id=19951220-1). He expressed a view that crews from US flatland were so accustomed to direct clearances that it made them quite complacent of the issues associated with off-airways flying in places where it can kill you.

I'd be very interested to know whether ATC has responsibility for terrain clearance in other states on a "direct to" clearance, particularly if that is initiated by the flight crew.

[M609]

In Norway, ATC is not responsible for terrain clearence in the "direct" scenario, so if on a SID, and given "cleared direct XXXXX", crew should not set course until above MSA or minimum track alt.

That said, any controller that have worked more then 2 minutes in alpine condtions will add "when ready" or "when sufficent altitude" etc to the direct clearence. (Or just wait until they pass MSA.......like I do!)

I have seen to many crews leave SIDs well below safe altitude.

[sumosan]

Military rules - and mil provides a service to a significant number of off-route CAT flights - say the controller is only responsible for terrain separation when providing Radar Control.

[Little Friend]

Well I think a healthy scepticism is what's needed. IE we all check each others work.

I was a charter pilot for some years before flying "milk runs" for a while and am now in and out of difficult airfields/airspace.

Funny old thing I feel safer now than I did on the (easy)"milk runs"-boredom being airmanships worst enemy.

And bad news upon us all again (Hellios); lets do our best!

Thanks for the input

[Scott Voigt]

In the US we are responsible for terrain as to our clearances, in other words, we can not clear you somewhere that is below our MIA (minimum instrument altitude) or MVA (minimum vectornig altititude) unless ceratain criteria are met. What you "should" hear us say is leaving XXX cleared direct XXXXX if you are climbing out on a departure or just on your own nav and are not yet above the MIA or MVA.

As to the Cali crash. There were many issues on that one. Not the least language. There was non specific language being used and the controllers were confused as to what the AA pilot was saying, and there was confusion on the AA flight deck as to what was actually being said by the controllers. The pilots requested direct, but the name on the arrival had direct in it and the controllers had no idea that the AA was off the arrival when they gave him a lower altitude. To compound the problem, the fix that the pilots entered into the FMS was the same as anther fix in the database that was in another country, so the FMS dutifully took the aircraft in the wrong direction. This lead to even greater confusion in the cockpit which along with other events helped lead to the tragedy.

regards

Scott

[pukeko]

New amendment to Doc 4444 effective November will change this, so that terrain during direct routing is also ATCOs responsiblity.
Sorry, don't have text to hand right now - maybe someone else?

[Pierre Argh]

Just as I thought, seems every country, ATS provider has their own rules.... makes it simple for the pilot to know where they stand?

[Jazz]

I find this thread very interesting. Are we saying that we never really know what the rule of an ATC unit in any given country is in relation to terrain clearance? It appears that in the UK ATC will ensure terrain clearance on a direct routing. But what about Spain, France, Italy etc?

The fact is that the ATC units in mountainous airports such as Malaga and Nice regularly give a clearance shortly after departure for an aircraft to fly direct to a waypoint while the aircraft is still well below the MSA for that waypoint, and indeed sometimes the aircraft is even well below its present MSA, allbeit while complying with the MSA for the SID it is tracking. Is it safe to accept any direct clearance from ATC, and accept that you are covered for terrain clearance?

My understanding has always been that terrain clearance is the full responsibility of the pilot unless when under radar vectors. I am confused by the term "radar control" and particularly "positive radar control". Pilots of commercial aircraft operate within controlled airspace almost all of the time, and therefore are almost always under radar control. Is a "cleared direct" instruction a radar control clearance, therefore ensuring terrain clearance?

I cannot figure out how, if I take off from Malaga runway 32 straight into high terrain (MSA 9000ft, if I remember correctly), and passing 3000ft I am cleared direct to a waypoint, the ATC unit can ensure terrain clearance, as I head straight for the mountain. Some people refuse the offer and continue to fly the SID, others accept the direct. It also regularly happend during the approach, cleared direct to a point that is below the MSA, and again people regularly accept it.

Can anyone offer any reference either ICAO or AIP from any country which could shed some light on this? The ICAO Pans ATC reference above was very useful, but anything else would be appreciated, particularly from the operations side.

Any comments appreciated.

Jazz.

[Pierre Argh]

Big snag... as highlighted above, despite ICAO's best efforts there are global differences, closer to home you have differing interpretations from UK Civil and Mil ATCO's.... Bottom line, under the heading of Duty of Care a controller should not give an instruction or advice that they know might endanger the aircraft, irrespective of service and class of airspace, unless given with a clear caveat. Not much consolation when you're in the bottom of a smoking crater?

Ultimately (and I know this is a cop-out but) the PILOT is responsible for the safety of the aircraft, so has the final responsibility for terrain clearance. But, as a Controller, if I issue a "direct" clearance I would assume that the level allocated should provide terrain clearance (as I would consider that a vector?)... but if it's "own navigation" then I feel it then becomes the pilot's responsibility (no vector)... anyone?

[DFC]

Jazz,

If you climb straight out from 32 at Malaga, the minimum radar vectoring altitude is;

4000ft as soon as you are airbourne and then 5500 from 13 to 50 miles out from Malaga. There are blocks left and right of that track with minimums of 7000.

Can you depart straight out and reach 5500 by 13 miles?

Regards,

DFC

[yarrayarra]

I am currently having discussions here in OZ about terrain clearance on departure in a non-radar environment.
My understanding is that the pilot will:-
Set course at or above the LSALT for the route segment within 5 miles of the departure earodrome
My question is:- if/can ATC clear the aircraft to track initially on a diversion track (to facilitate separation with other traffic) then what is the LSALT for that diversion track (not being a published route) and what are the responsibilities for the pilot and/or ATC to ensure terrain clearance?

[Jazz]

Thanks DFC

I take your point. However I use the minimum vectoring altitude plate to let me know the basis on which the controller allows me to descend me below the MSA when being vectored. I took this as being, as the title suggests, the vectoring altitude limits.

I can't say I would be happy to take a direct in IMC on the basis of a vectoring safe altitude chart alone, particularly if an engine fails and you are not sure about reaching the safe altitude while on the direct track.

I did a bit of research on this, and found the following under ICAO DOC-8168 (Ops), chapter 3 "altimeter corrections":

"Note: the determination of the lowest usable flight levels by air traffic control units within controlled airspace does not relieve the pilot in command of the responsibility for ensuring that adequate terrain clearance will exist, except when an IFR flight is being vectored by radar."

I believe this clarifies it somewhat. Pilots can accept a direct clearance, once they know they will clear the terrain. As Clint would say, you have to ask yourself the question, do I feel lucky....

Regards

Jazz.

[DFC]

Jazz,

The guy who surveyed and calculated the radar vectoring chart is often the same guy that surveyed and calculated the MSA.

Everything in 8168 assumes that all engines are operating and it is up to the operator to come up with any OEI procedures it needs.

From what I can see, despite ATC responsibilities while vectoring, ATC have no responsibility as soon as you loose an engine and can no longer make the required terrain clearance i.e. ATC vector on the basis of all engines operating all the time and when one stops ATC simply holds up it's hands and say - we are no longer responsible sort yourself out using your own procedure.

What Malaga makes intersting is that the MSA seems to make the appropriate extra clearance from high terrain (+2000ft) while the radar chart in the same place seems to only use 1000ft.

Regards,

DFC

[ATCO1962]

I work at a unit that utilises radar control in most of our airspace with the odd bit of procedural airspace thrown in to confuse the issue.

After many years of using both types of airspace at a number of units, I try as much as possible to assume the responsibility to ensure terrain separation for IFR aircraft in controlled
airspace. The reason for that is precisely because there are so many differences of opinion and rules around the world. If I don't think I can provide terrain separation for a pilot, then I will clearly place that responsibility on the pilot by issuing instructions that leave no doubt that the pilot is the one staying away from the hard stuff. I know some of you will say that that's too hard for your airspace, but we have the luxury here, at least usually, of being able to do so.

With regard to diversionary climbs out of non-radar units, where I was trained, we had VOR/DME sector altitude charts available so that you could issue departure radials to departures around inbounds. The understanding was that you, as the pilot, would climb visually to the minimum sector altitude and then outclimb any steps ahead of you until you were established on track at your MSA. Worked a treat. If you couldn't do that, a SID was used.

I absolutely agree that while under radar control and on a vector that the ATCO should be providing terrain clearance but that comes with a warning. It has been known for a controller, for whatever reason, to leave an aircraft on a vector through a centreline/final approach towards high ground without realising it. We have that problem partially solved here by an AIP instruction that tells pilots to intercept the final approach of the runway being used if on a heading unless specifically advised by the ATCO.

In all cases, situational awareness is a must and if you feel the hairs on the back of your neck go up, call the controller. I'd rather feel embarrassed than traumatised by an oversight. If you have any doubt at all, call, and if you feel you've gone below a safe altitude, start climbing without thinking about it. We can do the damage control later.

I'll be donning a cap now for the incoming that I know will be heading my way based on that last paragraph.:uhoh:

[yarrayarra]

--The understanding was that you, as the pilot, would climb visually to the minimum sector altitude and then outclimb any steps ahead of you until you were established on track at your MSA--
What I'm trying to ascertain is what happens if the pilot cannot climb visually to the MSA ie the cloud base is below the MSA. How does the pilot /the ATC process the aircraft to the MSA on the diversion track. And whose responsibility is it- pilot or controller

[ATCO1962]

Yarra,

The decision was made on observed met conditions. If there was any doubt as to a pilot's ability to stay VMC until the lowest sector altitude on the chart, a SID was issued.

Once the aircraft was safely in the sector and if he then entered IMC, it was the pilot's responsibility to be able to outclimb the steps ahead of him based on known aircraft performance. Obviously ATC can't help from that point on.

It worked very well because diversionary climbs rarely went beyond 15 miles and the sector charts went out to 50 miles (I think), leaving pilots plenty of time to intercept track above the MSA.

The departure clearance was something along the lines, for instance, of, " XXXXX climb the 248 radial to 7,000 ft, maintain 4000ft to 8DME, climb in accordance with the VOR/DME sector altitude chart" It's been a long time since I issued any such clearance so things may have changed, but it was sure a lifesaver at times at the small approach/tower unit I first worked at. Those were the days!!

[yarrayarra]

Thanks ATCO1962.
The reason I'm asking is that here in OZ there are some regional airports without radar and without SIDs. According to AIP the pilot is required to set course on departure within 5nm at or above the LSALT. (ie "clear for take of make left/right turn) One of the common separation solutions is to fire an aircraft, regardless of weather conditions/cloud base, out on an obscure radial in order to establish early lateral separation.
If the aircraft is on a known published route then the pilot knows what the LSALT is and can plan accordingly. My understanding is that on this obscure diversion the Minimum Sector Altitude should be used (after all what other LSALT is there?) which may be substantialy higher than a nearby published route. Therefore in order to track on the diversion you first need to clear the aircraft on a KNOWN route until the aircraft reaches the Minimum Sector Altitude after which the aircraft can can instructed to track and intercept the diversion route.
I know this sounds cumbersome but following a recent incident (which has yet to be investigated completely) I find it difficult to expect a pilot, after reporting ready, to have to instantly change and digest all the factors involved in departing on a non published diversion route without some chance of getting something wrong.
Just wondering whether or not I'm making a "mountain etc" when it is really the pilot's responsibility to work all that out. Me-- I'll do everything I can to give the pilot a fighting chance!
Thanks

[ATCO1962]

yarra

One of the great things about living in our current era is that this conversation may very well be a thing of the past if modern avionics and aircraft performance are headed where I think they are.

With the kind of overlays they have or are proposing to have on primary navigation displays, it seems like we'll not have to worry about such things except in the event of an emergency. Even though MLS is already obsolete with the advent of GPS derived situation information, it pointed the way towards unusual flight paths based on a smart use of modern technology and I suspect that we'll be putting such technology to good use soon in the area of terrain separation in non-radar areas.

In fact, we are already. Look at the displays that are showing synthetic terrain information in a user-friendly, 3-D way. I'm not sure how many aircraft are equipped with such displays, but it's only a matter of time before they will be standard, even on lighties. Then we will be able to give flexible departure instructions to departing aircraft in non-radar airspace easily, that is, if we are still required and Big Brother hasn't taken over:sad:

Have a good day!

[yarrayarra]

ATCO1962
Know what you mean about the Big Brother- cheers

[Pierre Argh]

ATC have no responsibility as soon as you loose an engine and can no longer make the required terrain clearance True to an extent... except MAP profiles are generally calculated on minumum Rate of Climb that allows for engines out... I also believe in the UK, the CAA requires that an aircraft shall be able to maintain level flight with just one engine remaining (?) However if a pilot informed me, as a controller, that he could not maintain height I would certainly consider vectoring him towards low ground, towards the coast etc so that (s)he can get visual contact with the surface and so better effect the inevitable?

As for allocating diverse vectors on IFR departure (described by Yarrayarra) that seems very dodgy. IMHO you use a planned profile, either the standard one designed by ATC or which the pilot has accepted their own responsibility for TC and therefore should know and take into account SALTs, Obstructions etc. You make it up at your peril?

[yarrayarra]

Pierre-thanks.
I'm in agreement about the dodgy bit. In VMC there's no problem. What worries me her in OZ, is that these "obscure" tracks are being used in non radar environmets with no consideration for how the pilot is getting to the LSALT (whatever that is). Now it could be argued that the pilot should analyse this amended tracking and work out the LSALT / climb performance etc, and if unabl;e to comply with IMC climb gradients, ask for something else. I just don't think pilots have the tools readily at hand to do that "off the cuff" and I believe ATC are putting aircraft into situations outside the norm without any consideration for the consequences.

[Dehavillanddriver]

Yarra

There is NO requirement to set course within 5 nm despite what AIP says.

In our company (major 737 operator) if it looks like that we will be entering cloud below the LSA at an airport where there is no published SID we advise the tower that we will be flying our single engine contingency procedure.

By that I mean that we will be tracking by a pre-determined track that ensures terrain clearance up to the LSA on one engine. By flying it on 2 we are obviously going to get to the LSA far faster, but nonetheless we know where the aeroplane will be in relation to terrain at all times.

It isn't popular with ATC at times but that is just tough, we need to make sure that we don't wnd up in IMC below the LSA with no idea of where the terrain is - and then add to that the possibility of having an engine failure in IMC below the LSA - you need to make sure that you know where you are in relation to the terrain.

PM me if you want more info

[pukeko]

I mentioned earlier in this topic that ICAO has an amendment to Doc 4444 PANS-ATM in November this year, that makes terrain clearance the controller's responsibility for a "direct to".

What countries are going to implement this change?
How do we know who's doing it and who's not?

[DFC]

What countries are going to implement this change?
How do we know who's doing it and who's not?

Can't answer the first question. However to find ou the answer to the second one, chack the GEN section of the AIP for that country and there will be a section that lists all the differences between that countries procedures and the ICAO Standards.

Jeppesen have some of the differences listed in the ATC section for each country.

Regards,

DFC