SIDs and the MSA

[homerj]

Heres a scenario.

Initially cleared on an SID.

On taxi ATC say " Disregard the SID , after departure route direct to XXX "

MSA in the direction of the new waypoint is 3000ft.

Do you need to track straight ahead till 3000ft or are ATC responsible for ensuring your new departure will keep you safe.

PS there was no omnidirectional procedures in the Jeppys.

Thanks

[None]

Do you need to track straight ahead till 3000ft or are ATC responsible for ensuring your new departure will keep you safe.

You have done your pre-flight planning well, now take that to the next step. That is, I would encourage you to clarify this before takeoff.

My opinion is that I am always responsible for my own terrain separation. For South America flying (and any flying in mountainous terrain areas), I suggest this is procedure, not technique.

What part of the world is this operation takeing place?

[homerj]

In Europe , MSA within 25 miles of 5000ft so no major high ground.
In the end I climbed to 3000ft before the turn but could we have turned safely at 1000ft agl

[BOAC]

Can he/she see the terrain? 2 additional significant questions for the Captain:

1) Has he/she studied the chart so as to know where the cumulo-granitus is that causes the '3000' MSA? IE can you complete flap retraction and get above it before you hit it?
2) Does he/she have a 'plan' if an engine goes?

As 'none' says, assuming satisfactory answers to the necessary commonsense questions, yes, of course.

I've taken many many 'directs' in my time, all reviewed, discussed and 'thought through'.

We are also, of course, assuming that 'straight ahead till 3000ft' is safe? You have not said. One hopes the Captain knew!

[ab33t]

PIC is responsible at all times , identify route and high obstacle /terrain if you are not on a SID you need to plan deaprture with ATC , Im sure you would have received a alt clearance on departure

[bfisk]

Here's my two cents:

Main question -- visual up to MSA? If so, and deemed that you have adequate climb on all engines and room to maneuver in case of engine failure, ok to turn as early as you deem safe.

If not visual, follow SID/climb procedure as appropriate up to MSA/COT (climb on track altitude). Unless cleared "when ready direct...", inform ATC that you need to follow SID/CLP up to xxx altitude before turning on course.

[Mohit_C]

Whilst on the same topic, can someone confirm that it is the PIC's reponsibility for terrain clearance in VMC but the ATC's reponsibility in IMC and under radar vectors?

Cheers.

[galaxy flyer]

Mohit_C

While PANS-RAC 4444 would lead one to believe just that--I have been cleared by Sevilla to descend to an altitude that would uncontrovertibly impacted the terrain, near the Martin VOR. I know this because I was on the flight deck, did not hear the clearance, but the crew descended, got a GPWS warning will before reaching the cleared altitude. I then got in the seat (heavy crew operation) queried ATC and got the clearance confirmed. The ATC controller said we needed to provide terrain clearance.

GF

[flyburg]

Hi, I had the same question once on a dutch forum and this was the answer I received from an air traffic controller:

ICAO Doc 7030 (EUR) Regional Supplementay Procedures 17.6.1 :

"Unless an IFR aircraft is receiving navigation guidance in the form of radar vectors from ATC, the pilot is resonsible for obstacle clearance. Therefore, the use of RNAV does not relieve pilots of their responsibility to ensure that any ATC clearance or instruction is safe in respect to obstacle clearance. ..."

As further back up, you should repost the question in the ATC section and get some answers from the ATC guys.

Greetings

edit: this is how I have always applied the rule myself: when on airways or on a direct clearance you are responsible for your own terrain clearance, when being radar vectored ATC is responsible. ATC has minimum vectoring altitude charts which will be below MSA published altitudes.

Note though that although being radar vectored you should always maintain situational awareness in regard to terrain and question ATC when unsure about terrain clearance(also a rule).

[Pitch Up Authority]

You are on an IFR flight plan so IFR rules apply.

A SID is exactly what it says. A STANDARD instrument departure.

If they clear you via a non standard instrument departure you have to comply with IFR obstacle clearance limits yourself.

There are a few things you can use.

Close to the airport you could use circling minima as a reference.
Next thing to look at is the Instr App on the side you are climbing.
Minimun vectoring altitudes are also an option.
The the MSA can be of some value.

If you know your rate of climb and average ground speed you will have a good idea where you will be and at what altitude.

Other option is to simply refuse the clearance.

[FlyPete]

In case no SID is used, omni directional departure applies. Minimum initial turning altitudes and climb gradient restrictions can be found on airport charts. If there's no restricting terrain around airport, then 400ft agl initial turn and 3.3% climb gradient guarantees obstacle clearance.

[galaxy flyer]

Except in the UK, where it is 500' AFE and then 3.3%. No,I don't know why, but it is in the UK AIM.

GF

[bookworm]

edit: this is how I have always applied the rule myself: when on airways or on a direct clearance you are responsible for your own terrain clearance, when being radar vectored ATC is responsible. ATC has minimum vectoring altitude charts which will be below MSA published altitudes.

PANS-ATM 8.6.5.2 says:

When vectoring an IFR flight and when giving an IFR flight a direct routing which takes an aircraft off an ATS route, the 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. (My bold.)

The usual caveats about division of responsibility apply.

"Disregard the SID , after departure route direct to XXX" is, in the absence of omnidirectional departure procedures, somewhat lax. I would expect at the very least, "after passing altitude yyyy ft, route direct to XXX".

[RAT 5]

Interesting point about Spanish ATC. I too have been cleared to an altitude 3000' inbd MGA VOR for right base 31. It was some years ago, but it was below MSA 5000' for the VOR and would have taken us into cloud. I chose to level 6000' VMC on top until certain we were over the wet stuff. ATC queried this, but to avoid a prolonged argument I didn't repsond for a while, then declared we were leaving 6000 for 3000'. You could hear the shrug of shoulders and feel the que?
For Seville it is common to be given a descent to final patform alt 'subject to safety altitudes". This means ATC do not give step clearances, but I wonder if they are watching you for safety altitude and terrain clearance purposes? I jusy wonder if they will jump in if some nutter dives straight for 3000'?

[hawk37]

Some Frightenly Different Beliefs

Well Gentlemen, I'm reading some clearly conflicting interpretations on who is assuming responsibility for providing terrain clearance while under IFR.

Galaxy Flyer ascerts in post 8 that Spannish atc will clear an aircraft to an altitude which does not provide terrain clearance at the aircrafts present position, leaving it up to the crew to choose safe altitudes as they progress. I'm presuming this is while on a clearance direct to a point, or on an airway.

Flyburg in post 9 basically says the same, unless on radar vectors.

While Bookworm in post 13 seems to have a PANS quote that atc accepts responsibility when giving an aircraft a vector or a DIRECT (my bold) routing. However, this does not seem to include clarifying that atc assumes altitude clearance responsibilities if a descent clearance is given while on an airway. Bookworm, could you perhaps elaborate?

[galaxy flyer]

RAT 5

Sevilla didn't say a word that day. That was exactly what they did--"cleared to 4000 (platform at LERT), 65+ miles east with no restrictions on when to leave FL 070. Crew assumed they could descend and ATC was providing terrain clearance. It won't be the ATCO being carried by six.

Hawk 37

I don't assert that Spanish ATC will clear you to an altitude that does not provide terrain clearance, I merely said that controller on that day cleared to descend to platform but didn't put a restriction on that clearance that would have provided terrain clearance. When I got in the pilot's seat and ATC that we were now at FL 070 and would maintain it until reaching the IAF, he just said that was approved. BTW, we were in cloud on the descent when the GPWS sounded and VMC at FL 070.

ATC in South America is also famous for doing such things, I presume, they leave terrain clearance to the pilot.

GF

[bookworm]

While Bookworm in post 13 seems to have a PANS quote that atc accepts responsibility when giving an aircraft a vector or a DIRECT (my bold) routing. However, this does not seem to include clarifying that atc assumes altitude clearance responsibilities if a descent clearance is given while on an airway.

It's just in a different section. 4.10.3.1 says:

"Except when specifically authorised by the appropriate authority, cruising levels below the minimum flight altitudes established by the state shall not be assigned."

I've always taken that to mean that assigned levels on airways must be at or above the MEA. It does, however, come with a strong caveat:

"Note 3 - The objectives of the air traffic control service as prescribed in Annex 11 do not include prevention of collision with terrain. The procedures described in this document do not relieve pilots of their responsibility to ensure that any clearances issued by ATC units are safe in this respect. When an IFR flight is vectored or given a direct routing which takes the aircraft off an ATS route, the procedures in 8.6.5.2 shall apply."

Which is about as useful as reminding pilots that they sit at the pointy end.

[abc1]

Day?
Night?
IMC/LVO?

''Unable comply"

[Vage Rot]

If there's any doubt then there's no doubt - ASK!!

I always assume that I'm responsible for my own terrain seperation, consult the relevant topo and make sure I don't hit the cumulus granitus. If you are not happy then clarify the clearance, if it's somewhere unfamiliar then study the terrain on the topo, draw out the approach/sid if you have to. That has saved my bacon a fair few times.

The one that nearly got me was about 10 years ago, cleared to descend to the next sector safe alt on the radar Vector chart, IMC, then 'Avoiding action, turn right 090 degrees - pop up traffic 12-O'clock at 4 miles' Unfortunately, that pointed us straight at a 3700ft peak when we were cleared to 2700ft in the adjacent sector. Fortunately, we noticed!
Fly safe, ask that stupid question.

[hawk37]

I have been cleared by Sevilla to descend to an altitude that would uncontrovertibly impacted the terrain

Not wanting to get in an argument with you GF, you've way more experience in this than me. But this quote above from you is why I said you assert:

"that Spannish atc will clear an aircraft to an altitude which does not provide terrain clearance"

Platform altitude, guess I'll have to look that one up, and see how it affects atc cleared altitudes.

So...I was just trying to understand how the atc system works. Maybe I don't understand the nuances, or maybe the controller made an error, or maybe I'm missing some crucial information. But this thread has produced posts that shows terrain clearance situations that I don't have a clear understanding of.

Bookworm, as always, digs up interesting docs. Will have to read closely and see how this fits in to the thread. Unless someone else can straighten me out