Missed approach (?) when glideslope fails

"Hilton" wrote in message
ink.net...

The problem is that you have no missed approach procedure to follow.


Show me an ILS without a missed approach procedure.



Let's
say, for example, that the missed is a 180 degree turn back to the LOM.
If
you start your turn early (i.e. fly the missed right now), you may hit a
mountain.

i.e. you must have a way to determine (at least approximately) where the
MAP
is; for examples are GS, DME, VOR, timing...


Easily done. A standard 3 degree GS descends 318' per nautical mile,
altitude above DH is directly proportional to distance from the MAP. To
make the arithmetic simpler 300' per mile is a close enough approximation.

"Hilton" wrote in message
ink.net...

Steven, when would you start your turn back to the LOM (or in any other
direction)?


At the point specified in the procedure.



The missed approach starts from the MAP (DH) - since you cannot ensure you
are at the MAP, you never really know you're flying the published missed -
therefore all bets are off so to speak.


What makes you think I cannot ensure I'm at the MAP?

Ron Rosenfeld wrote:

Hilton wrote:
what the heck do you do (can you do) if you're in
IMC on an ILS and your GS fails? You're screwed and only luck will save
your butt

You can't be serious with that claim.

Firstly, please note that after the word "butt", I had "(it may be less
dramatic when surrounded by flatter terrain)." So, we're assuming
mountainous terrain or other nearby obstacles.

When would you start flying the missed?
How would you start flying the missed?
Are you guaranteed to be flying the missed approach as published?

Hilton

"Hilton" wrote in message
ink.net...

Firstly, please note that after the word "butt", I had "(it may be less
dramatic when surrounded by flatter terrain)." So, we're assuming
mountainous terrain or other nearby obstacles.

When would you start flying the missed?


At the point specified in the procedure.



How would you start flying the missed?


In the manner specified in the procedure.



Are you guaranteed to be flying the missed approach as published?


Yes.

Steven P. McNicoll wrote:

Hilton wrote:

Steven, when would you start your turn back to the LOM (or in any other
direction)?


At the point specified in the procedure.

[Obvious replies inserted] And that is? How would you identify it?


The missed approach starts from the MAP (DH) - since you cannot ensure
you
are at the MAP, you never really know you're flying the published
missed -
therefore all bets are off so to speak.


What makes you think I cannot ensure I'm at the MAP?

[Obvious replies inserted] And that is? How would you identify it?

And FWIW, please note that earlier in this thread I wrote: "i.e. you must
have a way to determine (at least approximately) where the MAP is; for
examples are GS, DME, VOR, timing..."

Hilton

Steven P. McNicoll wrote:

Hilton wrote:

Firstly, please note that after the word "butt", I had "(it may be less
dramatic when surrounded by flatter terrain)." So, we're assuming
mountainous terrain or other nearby obstacles.

When would you start flying the missed?


At the point specified in the procedure.

You work for Microsoft? [in reference to the "in an airplane!" joke]

Hilton

"Hilton" wrote in message
news

[Obvious replies inserted] And that is? How would you identify it?


Since I'm on the GS when my GS receiver fails my distance from the MAP is
directly proportional to my altitude above DH. A 3 degree GS drops 318' in
each nautical mile. If I'm about 1000' above DH I'm about 3 miles from the
MAP. Simple.

"Hilton" wrote in message
ink.net...

You work for Microsoft?


Nope. Do you hold an instrument rating?

Steven P. McNicoll wrote:
"Hilton" wrote in message
news
[Obvious replies inserted] And that is? How would you identify it?



Since I'm on the GS when my GS receiver fails my distance from the MAP is
directly proportional to my altitude above DH. A 3 degree GS drops 318' in
each nautical mile. If I'm about 1000' above DH I'm about 3 miles from the
MAP. Simple.


So, you're reverting to timing anyway. The only difference is you start
your timing at a point other than the non-precision FAF and try to
figure it out as you go. (Let's see, I was passing 2650 when I lost the
glideslope a few seconds ago, the DH is 852, the glideslope is 2.8
degrees, I drop XXX amount of feet from here to there at a rate of XXX
ft per mile, so I'll cover that distance in XX minutes/seconds). Sounds
like it would be a whole lot simpler to start the timing at the
non-precision FAF than try to do those computations on the fly as you're
starting to climb as you're trying to figure if it's your equipment or
the glideslope failure.

John

Peter wrote:
"David Cartwright" wrote:

The ILS timing thing is an odd one. It seems to me that it's done only
in the checkride It is hugely inaccurate.


It is highly inaccurate, yet it's a step above guesswork. The biggest
problem would be caused when a 90 degree turn is required at the MAP.
That turn only protects from obstacles if you start the turn at or after
the MAP (as specified by the procedure). If you start the turn prior to
the MAP, you don't get the obstacle protection afforded by the missed
approach procedure.

John