Crossing a stepdown fix high

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.

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.

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.

wrote in message
...


Tim J wrote:



The bottom line is the approach is the approach - I don't think it is
intended as a "suggestion." - why stay above the heights? Wouldn't you
rather get down as fast as possible than be in the clouds? The
altitudes on
the approach chart guarantee more than reasonable obstacle clearance -
not
performing the approach as published would also lead me to wonder if
there
are other things you would make up your own procedures for and as a DE I
would consider that a bad thing...

Another "bottom line" is that the stepdown altitude in a NPA profile is
a
*minimum* altitude.

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.

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.

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.

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.

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

Do restrict your altitude to the MEAs enroute too? The stepdowns depict the
minimum altitudes for each segment of the approach. There is nothing regulatory
about flying at those minimums. What you are advocating is what others have
called 'dive and drive', ie decending quickly at each crossing then leveling at
the mda for that segment until hitting the next stepdown fix. This certainly
does increase the workload (you have less time to react to the altitude if it is
decreasing at 1000 fpm instead of 3-500 fpm), as well as the consequences for
being a little bit behind the airplane. It also gives you fewer options
(altitude) should the engine start coughing. Just from the ergonomics
standpoint, it is more stressful to you and your passengers, not to mention to
the engine (shock cooling) and airframe. Most of the time, you've got plenty of
room between the fixes to do a gentle descent and still get you at the final MDA
in plenty of time to find the airport.




--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

It's probably about time for someone to bring up the Aspen approach =
again.
Be a little high and/or fast there, and you won't get down in time to =
land.
---JRC---

"Ray Andraka" wrote in message =
...
Do restrict your altitude to the MEAs enroute too? The stepdowns =
depict the
minimum altitudes for each segment of the approach. There is nothing =
regulatory
about flying at those minimums. What you are advocating is what =
others have
called 'dive and drive', ie decending quickly at each crossing then =
leveling at
the mda for that segment until hitting the next stepdown fix. This =
certainly
does increase the workload (you have less time to react to the =
altitude if it is
decreasing at 1000 fpm instead of 3-500 fpm), as well as the =
consequences for
being a little bit behind the airplane. It also gives you fewer =
options
(altitude) should the engine start coughing. Just from the ergonomics
standpoint, it is more stressful to you and your passengers, not to =
mention to
the engine (shock cooling) and airframe. Most of the time, you've got =
plenty of
room between the fixes to do a gentle descent and still get you at the =
final MDA
in plenty of time to find the airport.
--
--Ray Andraka, P.E.

"David Brooks" wrote in message
...

Is there any problem with controllers or examiners if I cross a stepdown
fix
several hundred feet above the depicted altitude? I believe that,
legally,
I can be at any altitude above the crossing minimum, but would this be a
bust of the PTS +/-100 tolerance, or cause a problem for ATC?


Assuming ATC hasn't issued an altitude restriction it's not a problem for
them, it shouldn't be a problem for an examiner as you're not wavering from
an assigned altitude.