Only official instrument approaches authorised under FAR?

"Peter" wrote in message
...

FAR 91.175 (a) suggests that it is not permitted to carry out a
descent in IMC except on an official published IAP.

Any views on this?

How would it differ if the entire procedure was done in Class G?


What would you use for terrain clearance, and what for separation from other
IFR aircraft?

In article ,
Peter wrote:

FAR 91.175 (a) suggests that it is not permitted to carry out a
descent in IMC except on an official published IAP.

It does more than suggest, it states it quite explicitly (for most of us,
neither of the exceptions are likely to apply):

"Unless otherwise authorized by the Administrator, when an instrument
letdown to a civil airport is necessary, each person operating an
aircraft, except a military aircraft of the United States, shall use a
standard instrument approach procedure prescribed for the airport in part
97 of this chapter."

How would it differ if the entire procedure was done in Class G?

Not in the least. All IFR rules apply in class G except for the
requirement to obtain a clearance.

"Matt Barrow" wrote:
What would you use for terrain clearance, and what for separation from other
IFR aircraft?

SIAPs offer terrain clearance, which is why they are mandated.

Clearances are what offer separation from other aircraft, and are not
available in CGAS. In CGAS, IFR flights are afforded no separation
services from ATC.

"Peter" wrote in message
...

FAR 91.175 (a) suggests that it is not permitted to carry out a
descent in IMC except on an official published IAP.

Any views on this?


FAR 91.175 (a) suggests nothing, it states, "Unless otherwise authorized by
the Administrator, when an instrument letdown to a civil airport is
necessary, each person operating an aircraft, except a military aircraft of
the United States, shall use a standard instrument approach procedure
prescribed for the airport in part 97 of this chapter."



How would it differ if the entire procedure was done in Class G?


It wouldn't differ in any way, the regulation is not limited by class of
airspace.

"Roy Smith" wrote in message
...
"Matt Barrow" wrote:
What would you use for terrain clearance, and what for separation from
other
IFR aircraft?

SIAPs offer terrain clearance, which is why they are mandated.

He's talking about doing an approach without an official SIAP.

Clearances are what offer separation from other aircraft, and are not
available in CGAS. In CGAS, IFR flights are afforded no separation
services from ATC.

Re-read his question.

In a previous article, Peter said:
"Steven P. McNicoll" wrote
FAR 91.175 (a) suggests nothing, it states, "Unless otherwise authorized by
the Administrator, when an instrument letdown to a civil airport is
necessary, each person operating an aircraft, except a military aircraft of
the United States, shall use a standard instrument approach procedure
prescribed for the airport in part 97 of this chapter."

Does that mean that, on an IFR flight, one is not allowed to descend
below the MOCA except on a published IAP?

It says "when an instrument letdown...is necessary" that you shall use an
instrument letdown. Isn't that sort of circular? It doesn't actually say
when an instrument letdown is necessary.


--
Paul Tomblin http://xcski.com/blogs/pt/
"You must be smarter than this stick ---- to put a machine on the
Internet."

"Peter" wrote in message
...

Does that mean that, on an IFR flight, one is not allowed to descend
below the MOCA except on a published IAP?

One could read 175 as saying that if an official IAP is provided, it
must be used.


No, it means that unless otherwise authorized by the Administrator
nonmilitary aircraft of the United States operating under IFR are not
allowed to descend below the minimum IFR altitude when an instrument letdown
to a civil airport is necessary except on a published IAP.

It says "when an instrument letdown...is necessary" that you shall use an
instrument letdown. Isn't that sort of circular?

It doesn't quite say that... it's more like "when an instrument
letdown...is necessary to an airport... that you shall use =OUR=
instrument letdown to =THAT= airport." This looks like it precludes
shooting an approach to ABC and then slipping off to land at DEF, and it
certainly precludes home-grown approaches unless otherwise authorized by
the administrator.

Jose
r.a.misc snipped. I don't follow that group
--
He who laughs, lasts.
for Email, make the obvious change in the address.

"Paul Tomblin" wrote in message
...

It says "when an instrument letdown...is necessary" that you shall use an
instrument letdown. Isn't that sort of circular? It doesn't actually say
when an instrument letdown is necessary.


An instrument letdown would be necessary whenever there's no way to descend
without one. Already at the MIA and still in IMC? Visual, contact, or
radar approach not an option? Looks like an instrument letdown is
necessary.

"Peter" wrote in message
...

"Steven P. McNicoll" wrote

FAR 91.175 (a) suggests nothing, it states, "Unless otherwise authorized
by
the Administrator, when an instrument letdown to a civil airport is
necessary, each person operating an aircraft, except a military aircraft
of
the United States, shall use a standard instrument approach procedure
prescribed for the airport in part 97 of this chapter."

Does that mean that, on an IFR flight, one is not allowed to descend
below the MOCA except on a published IAP?

Correct, provided that an instrument letdown is necessary (ie, you're in
IMC).

One could read 175 as saying that if an official IAP is provided, it
must be used.

Can you explain how it could be read that way? You're proposing an exception
to the stated requirement--an exception in the event that no SIAP exists.
But no such exception is stated in the rule itself (it doesn't say, for
instance, "shall use an SIAP, *if any*"). Unfortunately, we can't
legitimately construe a rule to include an exception that we just make up
ourselves.

--Gary