Crossing a stepdown fix high

So what are you saying? The approach chart is/was wrong or the pilots made
an error?


wrote in message
...


"Steven P. McNicoll" wrote:

wrote in message
...

If you think in terms of getting down to a stepdown to "get out of the
clouds"
that is a good way to find granite or trees instead of water vapor.
This
is not
just my view; the industry/government accident stats are replete.


Only if the published altitudes are wrong.

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

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

wrote in message ...


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


The hit obstacles because: They pilot descended over 300 feet below what the
altimeter would lead him to believe the MDA was, and they had a nearly hour old
altimeter setting which put them another 40 feet down. The trees were also a little
taller than the FAA had accounted for when they designed the appraoch.

They were well beyond the stepdown fix (about halfway to the runway). It's not clear
what the stepdown fix had to do with it. If they'd flown a similar apporach at an airport
with an 800 foot MDH, they'd have still hit obstacles.

The NTSB did make some comments regarding continuous descents rather than step
down fixes, but I don't think that it would have helped in this case. If you look at the
profile view actually flown (which has a 3.5 degree glideslope superimposed over it),
you find that if they had stopped at the MDA they would have gotten there only half
a mile further out than they would have done on a constant descent angle.

I was just trying to point out the obstacle clearances that the approach
charts provide.

I would like to see an accident report that found that the approach chart
was incorrect and caused a crash. Does anyone have an example?

I think rather it is the (improper) execution of the approach that is the
cause of the supposed huge set of examples of crashes. If you all find it
easier to make up your own descent profiles, go right ahead. I will not try
to convince you otherwise. I will continue to fly them as published.

tim

wrote in message
...


Tim J wrote:

That is ridiculous. If I follow the approach procedures I will stay
away
from the granite. I would recommend reading TERPS. Maybe I am an idiot
for
following the procedures as published, but it lets me work on the other
parts of flying and I have more time and effort left for the rest of the
work during an approach.

Good idea. I'll read those TERPs.

In article ,
"Ron Natalie" wrote:

wrote in message
...


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


The hit obstacles because: They pilot descended over 300 feet below what
the
altimeter would lead him to believe the MDA was, and they had a nearly hour
old
altimeter setting which put them another 40 feet down. The trees were also
a little
taller than the FAA had accounted for when they designed the appraoch.

They were well beyond the stepdown fix (about halfway to the runway). It's
not clear
what the stepdown fix had to do with it. If they'd flown a similar apporach
at an airport
with an 800 foot MDH, they'd have still hit obstacles.

The NTSB did make some comments regarding continuous descents rather than
step
down fixes, but I don't think that it would have helped in this case. If you
look at the
profile view actually flown (which has a 3.5 degree glideslope superimposed
over it),
you find that if they had stopped at the MDA they would have gotten there
only half
a mile further out than they would have done on a constant descent angle.




Not to mention that the weather was unbelievably ****ty. If I remember
the incident correctly, the storm had blown out the tower cab windows,
and the controllers had fled the building for fear of personal injury.

We're talking about

http://www.ntsb.gov/ntsb/brief.asp?e...07X04839&key=1

right? Unfortunately, the "full narrative available" link seems to be
stale, but http://www.ntsb.gov/publictn/1996/AAR9605.pdf is the full report.
It's kind of interesting to read.

If I follow the approach procedures I will stay away from the
granite. I would recommend reading TERPS.

I'm certain that Airperson is far more familiar with TERPS than you
are or ever will be.

His point is that certain types of procedures lend themselves to
certain types of errors. Nonprecision approaches have a far higher
error rate than precision approaches. The weak link is the limitation
on human ability to manage complexity; the only solution is reducing
complexity, either through technology (which is what a glide slope
does) or via pilot training, such as the constant rate descent.

To comment that "if they fly the approach as published, they won't hit
anything" is a very shallow analysis. Not every CFIT deviated
intentionally from the published approach.

"Tim J" wrote in
. net:

So what are you saying? The approach chart is/was wrong or
the pilots made an error?

The pilots made an error. Dive and drive is dangerous. 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.

--
Regards,

Stan

"Bob Gardner" wrote in
news:PZCjb.795942$uu5.139761@sccrnsc04:

When I was an examiner, I would have expected you to fly
the approach profile as published. Once upon a time I
decided to forego the "descent and maintain 2200 feet" on
the way in to BFI's ILS 13R, thinking that I would stay at
3000 and intercept the glideslope high....got chided by
Seattle Approach for doing so. Over the years I have
learned that ATC expects you to do the expected.

"Descend and maintain 2200" is not the same clearance as
"Maintain at or above 2200".

--
Regards,

Stan

Greg Esres writes:

To comment that "if they fly the approach as published, they won't hit
anything" is a very shallow analysis. Not every CFIT deviated
intentionally from the published approach.

The other question is what "as published" means for an NPA -- do you
make a vertical descent at every stepdown fix? The whole point of an
NPA is that there is no vertical profile published, only a series of
minimum altitudes.


All the best,


David

Tim J wrote:

So what are you saying? The approach chart is/was wrong or the pilots made
an error?

The pilots made an error under lots of pressure and adverse weather conditions.
The list of fatal accident reports where stepdown fixes are busted in G/A during
IMC is a very long list indeed.

The protection offerred by dive-and-drive is substantially less than with a
constant angle or even a constant rate descent.

I guess this word hasn't gotten very far in the light aircraft world.

Tim J wrote:

I was just trying to point out the obstacle clearances that the approach
charts provide.

I would like to see an accident report that found that the approach chart
was incorrect and caused a crash. Does anyone have an example?

I think rather it is the (improper) execution of the approach that is the
cause of the supposed huge set of examples of crashes. If you all find it
easier to make up your own descent profiles, go right ahead. I will not try
to convince you otherwise. I will continue to fly them as published.

What makes you think "as published" means dive and drive any more than it means
constant angle or constant rate?