Crossing a stepdown fix high

"Tim J" wrote in message
. net...
Perhaps I am wrong (as so many of you are pointing out)
but if I make a descent rate to arrive at a step down higher than
published,
it seems as though my descent rate has a good chance to not get me to the
MDA when the time is up (or distance) and I have to go missed. So
eventually I would have to do the dreaded "dive and drive" later anyway.


As long as you are at the LAST stepdown fix at the minimium altitude and
correct airspeed then what difference does it make what altitudes you
crossed the other stepdowns?

Mike
MU-2

"Mike Rapoport" wrote in message
nk.net...

"Tim J" wrote in message
. net...
Perhaps I am wrong (as so many of you are pointing out)
but if I make a descent rate to arrive at a step down higher than
published,
it seems as though my descent rate has a good chance to not get me to
the
MDA when the time is up (or distance) and I have to go missed. So
eventually I would have to do the dreaded "dive and drive" later anyway.


As long as you are at the LAST stepdown fix at the minimium altitude and
correct airspeed then what difference does it make what altitudes you
crossed the other stepdowns?


Quite -- think of what the word "minimum" means.

Stan Gosnell me@work wrote
The pilots made an error. Dive and drive is dangerous.

So is instrument flying in general. If we all just waited for CAVU, I
bet there would be fewer accidents. Tradeoffs are made between safety
and cost/utility all the time, and dive and drive is one of them.

I'm in
no particular hurry to get out of the clouds - at MDA is fine.
Why would anyone be in a huge hurry to get out of the clouds?
Being in a hurry is almost always dangerous, sometimes fatal.

It's not about being in a hurry to get out of the clouds - it's about
reaching MDA well before reaching the MAP. In other words - it's not
about rate of descent (I couldn't care less about spending an extra
couple of minutes in the clouds) but about angle of descent (I don't
want to reach MDA only seconds before reaching the MAP). This is
simply another one of those areas where the checkride diverges from
real life.

On the checkride, as long as you reach MDA prior to the MAP, you're
good to go. In real life, you actually want to land. When ceilings
are close to MDA (or broken such that they are above MDA in places and
below in other places) and visibility is limited by haze, mist, and/or
rain (especially at night), you're going to need some time to pick the
runway out of the murk - especially if the runway environment (such as
the beacon) is not correctly depicted on the plate. Otherwise, you're
going to be shooting the missed approach not because you didn't break
out prior to MDA but because you couldn't find the runway - at all or
until it was too late to land on it using normal flight maneuvers.

In limited visibility (especially at night) finding the runway is best
accomplished while the airplane is in level flight at MDA, and
configured and trimmed to fly hands off. To get to that state, it's
necessary to descend to MDA expeditiously (dive and drive), power up
and level off, and configure the airplane - all before reaching the
MAP - so you can devote most of your time to looking out the window.
If you must rush something, you're better off rushing the relatively
straightforward descent to MDA (flown purely as an instrument
maneuver) rather than the more complex visual segment, which often
requires at least some reference to instrument for aircraft control
and at the same time requires significant 'outside' time to find the
runway.

Of course CANPA (which is what the industry is moving to) is safer -
in the sense that it allows a less competent pilot to fly the approach
without putting too much strain on his less-than-stellar skills. The
cost is increasing the probability of a missed approach when weather
is at or close to mnimums AND requiring additional equipment that the
average small airplane lacks.

An excellent article on this topic was written by John Deakin, and is
available fromm AvWeb he
http://www.avweb.com/news/columns/182091-1.html

Michael

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(Paul Tomblin) wrote
I don't know if this would be considered "a healthy safety margin", but my
examiner said the same thing that my instructor did - that the PTS says
+100 feet/-0 feet, so you should always fly 50 feet high to give yourself
a bit of a buffer.

This is another of those areas where training for the checkride and
training for real life are different. Sure, it works - for passing
checkrides and for those times when the the weather is significantly
above mins. But in real life, I can think of several approaches I
made where doing this would have caused me to miss.

Michael

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"Mike Rapoport" wrote in message
nk.net...

"Tim J" wrote in message
. net...
Perhaps I am wrong (as so many of you are pointing out)
but if I make a descent rate to arrive at a step down higher than
published,
it seems as though my descent rate has a good chance to not get me to
the
MDA when the time is up (or distance) and I have to go missed. So
eventually I would have to do the dreaded "dive and drive" later anyway.


As long as you are at the LAST stepdown fix at the minimium altitude and
correct airspeed then what difference does it make what altitudes you
crossed the other stepdowns?

Well, that was a given in the theoretical scenario. The smooth descent is
calculated to arrive at the last stepdown altitude well before its fix (a
couple of miles at least), not to hit it exactly. I'm not trying to avoid
that last level-off.

Someone did mention unplanned winds, and that has made me rethink the setup
a little. Given time to plan in advance, a constant-rate descent, so long as
it clears all the minimums, seems to me to be better, and nicer to your
passengers. However, factoring in actual wind seems to break the
no-math-in-the-cockpit rule. There are now multiple constraints on your
chosen descent rate, while "dive and level off" leaves more margin for
wind-induced error.

-- David Brooks

"David Brooks" writes:

Well, that was a given in the theoretical scenario. The smooth descent is
calculated to arrive at the last stepdown altitude well before its fix (a
couple of miles at least), not to hit it exactly. I'm not trying to avoid
that last level-off.

Instead of imagining a ceiling right at MDA (or 50 feet above, so that
you have a chance of seeing the runway), let's take a more realistic
example, at least for where I live. MDA is 500 ft AGL and the ceiling
is 800 ft AGL with 1.5 SM visibility (fluctuating). You're not going
to see the runway at the FAF, five six miles back. Do you descend
fast to MDA and then level out for a few miles?


All the best,


David

Thank you Michael - you seemed to have been able to state more clearly what
I was trying to say since the start of the thread...

"Michael" wrote in message
om...
Stan Gosnell me@work wrote
The pilots made an error. Dive and drive is dangerous.

So is instrument flying in general. If we all just waited for CAVU, I
bet there would be fewer accidents. Tradeoffs are made between safety
and cost/utility all the time, and dive and drive is one of them.

I'm in
no particular hurry to get out of the clouds - at MDA is fine.
Why would anyone be in a huge hurry to get out of the clouds?
Being in a hurry is almost always dangerous, sometimes fatal.

It's not about being in a hurry to get out of the clouds - it's about
reaching MDA well before reaching the MAP. In other words - it's not
about rate of descent (I couldn't care less about spending an extra
couple of minutes in the clouds) but about angle of descent (I don't
want to reach MDA only seconds before reaching the MAP). This is
simply another one of those areas where the checkride diverges from
real life.

On the checkride, as long as you reach MDA prior to the MAP, you're
good to go. In real life, you actually want to land. When ceilings
are close to MDA (or broken such that they are above MDA in places and
below in other places) and visibility is limited by haze, mist, and/or
rain (especially at night), you're going to need some time to pick the
runway out of the murk - especially if the runway environment (such as
the beacon) is not correctly depicted on the plate. Otherwise, you're
going to be shooting the missed approach not because you didn't break
out prior to MDA but because you couldn't find the runway - at all or
until it was too late to land on it using normal flight maneuvers.

In limited visibility (especially at night) finding the runway is best
accomplished while the airplane is in level flight at MDA, and
configured and trimmed to fly hands off. To get to that state, it's
necessary to descend to MDA expeditiously (dive and drive), power up
and level off, and configure the airplane - all before reaching the
MAP - so you can devote most of your time to looking out the window.
If you must rush something, you're better off rushing the relatively
straightforward descent to MDA (flown purely as an instrument
maneuver) rather than the more complex visual segment, which often
requires at least some reference to instrument for aircraft control
and at the same time requires significant 'outside' time to find the
runway.

Of course CANPA (which is what the industry is moving to) is safer -
in the sense that it allows a less competent pilot to fly the approach
without putting too much strain on his less-than-stellar skills. The
cost is increasing the probability of a missed approach when weather
is at or close to mnimums AND requiring additional equipment that the
average small airplane lacks.

An excellent article on this topic was written by John Deakin, and is
available fromm AvWeb he
http://www.avweb.com/news/columns/182091-1.html

Michael

Please do not send email replies to this posting. They are checked
only sporadically, and are filtered heavily by Hotmail. If you need
to email me, the correct address is crw69dog and the domain name is
this old airplane dot com, but remove the numbers and format the
address in the usual way.

(Michael) wrote in
om:

It's not about being in a hurry to get out of the clouds -
it's about reaching MDA well before reaching the MAP. In
other words - it's not about rate of descent (I couldn't
care less about spending an extra couple of minutes in the
clouds) but about angle of descent (I don't want to reach
MDA only seconds before reaching the MAP). This is simply
another one of those areas where the checkride diverges
from real life.

We're talking about different things, I think. The OP was
talking about intermediate stepdown fixes, and so was I. IME, a
constant descent is safer than diving as quickly as possible to
an intermediate altitude, leveling off, and then diving again.
I agree you want to be at the MDA before the MAP, but it does no
real good to hit an intermediate altitude early. Even the
descent to the MDA isn't something I rush. Rushing to the MDA
can mean you see the ground far from the airport, go below the
MDA, and then encounter IMC again. I prefer to make a
stabilized descent to reach the MDA just before the MAP, and
continue the descent to landing. But if you're flying your
airplane, do it however you like. It's your life.

--
Regards,

Stan

Stan Gosnell me@work wrote
We're talking about different things, I think. The OP was
talking about intermediate stepdown fixes, and so was I. IME, a
constant descent is safer than diving as quickly as possible to
an intermediate altitude, leveling off, and then diving again.
I agree you want to be at the MDA before the MAP, but it does no
real good to hit an intermediate altitude early.

I can certainly agree with that.

Even the
descent to the MDA isn't something I rush. Rushing to the MDA
can mean you see the ground far from the airport, go below the
MDA, and then encounter IMC again.

That's why VDP's exist. If you descend below MDA prior to reaching
the VDP, you have only yourself to blame. If no VDP is charted, it's
easy enough to compute based on whatever descent angle you want to
fly.

I prefer to make a
stabilized descent to reach the MDA just before the MAP, and
continue the descent to landing.

In other words, CANPA. Just out of curiosity, do you normally fly
with a copilot? Perhaps one whose major responsibility on the descent
is spotting the landing area?

Michael

wrote in message
...

I guess the stats and industry/government studies are all wet then.


Please post the stats and industry/government studies that show aircraft
finding granite or trees at correctly published IAP altitudes.



The published altitudes weren't wrong at KBDL when the AAL MD80 hit the
trees near the stepdown fix.


I assume you're referring to AAL1572. The NTSB determined the probable
cause of that accident to be a descent below the MDA prior to having the
required runway visual references in sight. The impact with trees occurred
about 2.2 miles past the step-down fix.