Responsibility for Terrain Separation

[Mark Hargrove]

Not related to PE, but a general ATC question:

You're on an IFR flight plan in IMC, flying a planned element of your route. ATC issues a heading change (i.e., a vector) and a descent. Who is responsible for terrain separation?

-M.

[Mudhen]

Both. (Well kind of.)
ATC must guarantee that assigned altitudes will not violate Minimum Vectoring Altitude. (Unless an emergency exists, then not below Emergency Obstruction Video Map altitudes. EOVM)
Pilots should maintain situational awareness and be mindful of surrounding obstacles/terrain.
https://www.faasafety.gov/gslac/ALC/lib ... px?id=6583
Particularly:
9. GA IFR Operations in IMC Conditions on an IFR Flight.
c. Having the proper charts and approach plates for the intended flight. VFR charts, although not required, should be onboard because they can provide important obstacle and terrain data for an IFR flight.

[HRutila]

I guess the question I pose is why would ATC not be responsible for this? The IFR pilot is not in a position to audit the legality of an ATC-assigned altitude.

[jx_]

I guess the question I pose is why would ATC not be responsible for this? The IFR pilot is not in a position to audit the legality of an ATC-assigned altitude.

because FAR says pilots should operate in a safe manner and above the MIA at all times...etc.... That doesn't mean ATC won't get busted...but if you fly for a company that has a snitch installed you'll get it too.

[HRutila]

I guess the question I pose is why would ATC not be responsible for this? The IFR pilot is not in a position to audit the legality of an ATC-assigned altitude.

because FAR says pilots should operate in a safe manner and above the MIA at all times...etc.... That doesn't mean ATC won't get busted...but if you fly for a company that has a snitch installed you'll get it too.

I'm saying there is no situation in which ATC is permitted to suddenly discontinue providing terrain and obstruction clearance to an IFR pilot.

[Ryan B]

We kinda do if we issue a cruise clearance. I use that sometimes for airports without dod approaches. Though I'm honestly not sure what the pilot can do... go down to the MEA?

[jx_]

He didn't say "ATC is permitted to suddenly discontinue providing terrain and obstruction clearance to an IFR pilot"...he said 'both'.


However, here are 3 times ATC can discontinue providing terrain and obstruction clearance to an IFR pilot:

1) radar contact not yet established
2) radar service terminated/lost
3) aircraft established on published procedure with altitude guidance and ATC clearance to follow the procedure.

These are cases where ATC only has the obligation of spacing for traffic and MSAW alerts. ATC can terminate radar if non-radar spacing is used. (Assuming the controller has met all the coordination rules for every downstream sector)