Missed approach (?) when glideslope fails

You are on an ILS approach, DH 200'. The localizer-only MDA is 500'.
You are at 300' in IMC when the GS fails. Assuming you are timing the
approach, is it legal to climb to 500 and continue the approach?

It's rather academic, since if you can't see the runway at 300 feet, you're
unlikely to climb to 500, see it, and then be in a position to descend down
for a normal landing. But to answer your question, no it's not legal
according to 14 CFR 91.175(e)(1)(i) since you'd be operating below the MDA
for the LOC approach.

Section 91.175: Takeoff and landing under IFR.
(e) Missed approach procedures. Each pilot operating an aircraft, except a
military aircraft of the United States, shall immediately execute an
appropriate missed approach procedure when either of the following
conditions exist:

(1) Whenever operating an aircraft pursuant to paragraph (c) or (l) of this
section and the requirements of that paragraph are not met at either of the
following times:

(i) When the aircraft is being operated below MDA; or






"Yossarian" wrote in message
oups.com...
You are on an ILS approach, DH 200'. The localizer-only MDA is 500'.
You are at 300' in IMC when the GS fails. Assuming you are timing the
approach, is it legal to climb to 500 and continue the approach?

"Yossarian" wrote:
You are on an ILS approach, DH 200'. The localizer-only MDA is 500'.
You are at 300' in IMC when the GS fails. Assuming you are timing the
approach, is it legal to climb to 500 and continue the approach?

I don't know of any rule which explicitly says it is illegal, but my
personal opinion is that it's a stupid idea.

It's a stupid idea in the general sense because the middle of an approach
is no time to be changing plans and diagnosing instrument failures. Go
around, sort things out at a safe altitude, and figure out a new plan when
you have time to consider all your options.

It's a particularly stupid idea in the specific scenario you described. If
you're still IMC at 300 feet, what makes you think climbing to 500 will put
you in a position where you can see the runway?

Consider also how inaccurate timing is. In a typical GA airplane, 100 feet
above DH on the GS is about 10 seconds away from the ILS MAP; what makes
you think your FAF-MAP timing is accurate to within 10 seconds?

Plus, another thing. Transition from descent to climb profile involves
power changes, pitch changes, and trim changes. And all those again as you
level off at 500. Are you going to be doing all those things, and peering
out of the window at the same time trying to see the runway (all the while
paying attention to your timer counting down the last few seconds)? And
then more power/pitch/trim changes (plus get the gear up this time) a few
seconds later as you finally decide to go missed? Low, slow, and IMC is
the wrong place to be doing all these things.

"Yossarian" wrote in message
oups.com...
You are on an ILS approach, DH 200'. The localizer-only MDA is 500'.
You are at 300' in IMC when the GS fails. Assuming you are timing the
approach, is it legal to climb to 500 and continue the approach?

Legality-wise, the only offence someone could really try to prosecute you
for would be that of breaking the approach constraints of the equipment
available to you. Your defence (which I'm 100% sure the court would accept)
would be that the approach was legal until the equipment broke and
immediately switched you to a situation which was (strictly speaking)
illegal, but which you expeditiously got yourself out of by climbing to the
new MDA. Theory notwithstanding, though, the sensible way to go is execute a
missed approach, go back to the start, get the other approach plate out,
remind yourself of the minima, and have another go.

As others have said, I suspect this example is hypothetical - if you're at
300' on the glideslope of an ILS, you're a mile from touchdown and you'll
probably be over the runway by the time you've realised what's going on and
have climbed. It's not inconceivable, however, for something similar to
happen when (say) an airfield has published ILS (precision) and NDB
(non-precision) approaches, where the difference in DH is only a hundred
feet - you could in theory embark on the ILS approach, the glideslope could
fail at 350 feet, and you're still within the legal limits of an NDB
approach. Again, though, this doesn't necessarily mean it's a sensible way
to go.

D.

Is it safe or prudent given your level of skill? That is the question.

Yossarian wrote:
You are on an ILS approach, DH 200'. The localizer-only MDA is 500'.
You are at 300' in IMC when the GS fails. Assuming you are timing the
approach, is it legal to climb to 500 and continue the approach?

IMHO, there are far too many CFII's teaching students to transition
from an ILS approach to a LOC approach midstream, if the glideslope
fails.

Human beings are very habit oriented. Things are much more consistent
if we do things the same way every time. (Watch a professional golfer
getting ready for a drive a few times, and you'll see that they do it
the same way every time.)

The prudent (in my opinion) action, when the glideslope fails inside
the FAF, is to go missed and then get your head around the LOC
approach, regardless of where you are on the Final Approach segment.

If you have yet to reach the FAF, brief the LOC approach if you have
time. Otherwise, ask to hold at the FAF (if available) or take another
action that will give you the time.

Just my two cents.

-Rob

----
Rob Montgomery
www.scarylittleairplanes.org

Don't try to convert an ILS into a LOC in midstream. Go around and try again
(this assumes that radar is not available).

Bob Gardner


"Yossarian" wrote in message
oups.com...
You are on an ILS approach, DH 200'. The localizer-only MDA is 500'.
You are at 300' in IMC when the GS fails. Assuming you are timing the
approach, is it legal to climb to 500 and continue the approach?

On 6 Sep 2005 19:29:14 -0700, "Yossarian"
wrote:

You are on an ILS approach, DH 200'. The localizer-only MDA is 500'.
You are at 300' in IMC when the GS fails. Assuming you are timing the
approach, is it legal to climb to 500 and continue the approach?

That's how I was taught. You time the ILS approach, even though it's
not necessary, in case the GS fails and you can climb to the MDA and
continue as a LOC approach. I've read several articles advising that.
I was even told that not timing the ILS approach was a failure item on
the checkride, so I did as I was taught and timed the approach. I
guess it's good practice against the possibility of forgetting to time
the approach when it really does matter.

My GS is included in one radio, the Narco NAV122. The LOC and GS share
some components so if a common component fails, the whole thing is
suspect. In fact, the one time the radio did fail it was the
multiplexer that quit, though the failure was discovered on the ground
and not on approach.

I suspect that other installations may also share components in
unexpected ways, particularly antennas. If something fails, you don't
need to be puzzling about whether you can trust what's left while
you're 300' and barrelling down the glideslope. A miss allows you to
evaluate your condition from a safe altitude.

Unless your tanks are empty and you have seconds to get it on the
ground before the power fails. But then that's a whole different
scenario.

RK Henry

David Cartwright wrote:
"Yossarian" wrote in message
oups.com...

You are on an ILS approach, DH 200'. The localizer-only MDA is 500'.
You are at 300' in IMC when the GS fails. Assuming you are timing the
approach, is it legal to climb to 500 and continue the approach?


Legality-wise, the only offence someone could really try to prosecute you
for would be that of breaking the approach constraints of the equipment
available to you. Your defence (which I'm 100% sure the court would accept)
would be that the approach was legal until the equipment broke and
immediately switched you to a situation which was (strictly speaking)
illegal, but which you expeditiously got yourself out of by climbing to the
new MDA. Theory notwithstanding, though, the sensible way to go is execute a
missed approach, go back to the start, get the other approach plate out,
remind yourself of the minima, and have another go.

Not exactly. There is always the catch all "reckless" operation
violation. All it takes is an FAA guy to find out about this and
consider it reckless.


Matt

RK Henry wrote

I was even told that not timing the ILS approach was a failure item on
the checkride, so I did as I was taught and timed the approach.

You received incorrect information.

A miss allows you to evaluate your condition from a safe altitude.

A procedure required in the airline industry.

Bob Moore
ATP CFI