"position & hold" going away

In article . net,
"Steven P. McNicoll" wrote:

Then why did one airliner land on top of a commuter (iirc) a number of
years ago?

Were the conditions such that a pilot in position could see an approaching
aircraft?

My understanding is that the airport was VFR at at the time.

--
Bob Noel
no one likes an educated mule

"Bob Noel" wrote in message
...

My understanding is that the airport was VFR at at the time.


Let me know when you're sure.

Steven P. McNicoll wrote:
Let me know when you're sure.

http://www.ntsb.gov/ntsb/GenPDF.asp?...1MA018A&rpt=fa
http://www.ntsb.gov/ntsb/GenPDF.asp?...1MA018A&rpt=fi

16 miles reported visibility, 30000 scattered. That should qualify as
VFR for most people.

Ben Hallert
PP-ASEL

"Ben Hallert" wrote in message
ups.com...

http://www.ntsb.gov/ntsb/GenPDF.asp?...1MA018A&rpt=fa
http://www.ntsb.gov/ntsb/GenPDF.asp?...1MA018A&rpt=fi

16 miles reported visibility, 30000 scattered. That should qualify as
VFR for most people.


Yup, but Bob's question was, "Is the threshold always visible to the pilot
for all aircraft when
in normal landing configuration?" The aircraft in position on the runway
was an intersection departure.

The question remains, if neither pilot aboard the landing 737 could see the
Fairchild 227 on the runway, why should we believe the crew of the Fairchild
227 could have seen the incoming 737 if they had been cocked some thirty
degrees or so from the runway centerline?

Hi Steve,

My post was in response to the following exchange:

Bob Noel:
My understanding is that the airport was VFR at at the time.
Steven P. McNicoll:
Let me know when you're sure.

Best regards,

Ben Hallert
PP-ASEL

The question remains, if neither pilot aboard the landing 737 could see the
Fairchild 227 on the runway, why should we believe the crew of the Fairchild
227 could have seen the incoming 737 if they had been cocked some thirty
degrees or so from the runway centerline?

The accident happened shortly before sunset on runway 24. So the
pilots on the 737 would have been looking nearly into the sun whereas a
pilot looking back would be seeing a landing light in a darkening sky.

But regardless of the details of this particular incident, why not have
the redundancy of having both aircraft crews in a position where they
could observe and possibly avert an imminent collision?

"peter" wrote in message
oups.com...

The accident happened shortly before sunset on runway 24. So the
pilots on the 737 would have been looking nearly into the sun whereas a
pilot looking back would be seeing a landing light in a darkening sky.


How is it that they were able to see the runway but not an airplane of 95'
wingspan and 82' length sitting on it? Why would a pilot looking back see a
landing light in a darkening sky if the sun was brightly shining on the
approaching airplane? You can't have it both ways.

When I find the sun shining in my eyes like that I adjust my visor.



But regardless of the details of this particular incident, why not have
the redundancy of having both aircraft crews in a position where they
could observe and possibly avert an imminent collision?


That would require the airplane in position to turn towards approaching
aircraft and defeat the purpose of position and hold.

How is it that they were able to see the runway but not an airplane of 95'
wingspan and 82' length sitting on it?

I don't know; I wasn't there. But it doesn't seem unreasonable to me
that an airplane could appear to blend into the runway under certain
conditions, that being one of them. Granted, they could "see" the
airplane, inasmuch as photons reflected from the plane entered the eye.
However, it might not have been recognized as an airplane if the
contrast were low enough, there was enough glare, the pilots were
focused on ("fixated on?") some other aspect of the approach (maybe the
theshold markings, the far end, the sight picture...) It would clearly
be pilot error, but it's possible for pilots to =make= errors, even
experienced ones.

Why would a pilot looking back see a
landing light in a darkening sky if the sun was brightly shining on the
approaching airplane?

That depends on the albedo of the airplane, the angle it presented to
the sun, the brightness of the landing light, and the exact direction it
was facing. It does not sound unreasonable to me, although I wasn't
there at that exact moment.

Jose
--
Quantum Mechanics is like this: God =does= play dice with the universe,
except there's no God, and there's no dice. And maybe there's no universe.
for Email, make the obvious change in the address.

The accident happened shortly before sunset on runway 24. So the
pilots on the 737 would have been looking nearly into the sun whereas a
pilot looking back would be seeing a landing light in a darkening sky.

How is it that they were able to see the runway but not an airplane of 95'
wingspan and 82' length sitting on it?

Because they were human and sometimes make mistakes, especially under
conditions of poor visibility such as caused by having to look in the
direction of the sun near the horizon.

Why would a pilot looking back see a
landing light in a darkening sky if the sun was brightly shining on the
approaching airplane? You can't have it both ways.

Go out just before sunset and look at the sky in the direction opposite
from the sun. You should notice that it's already considerably darker
than at midday even though the sun has not yet set. Looking in that
direction a plane would be very easy to see because it would be
brightly lit by the sun and is set against a darker background sky. If
the landing light is on that would make it even more visible.

So at the time of this accident the crew of the landing plane had
relatively poor visual conditions while if the crew of the plane on the
ground had been in a position to look back they would have had
excellent visibility.

When I find the sun shining in my eyes like that I adjust my visor.

That helps but certainly doesn't fully eliminate the problem.

But regardless of the details of this particular incident, why not have
the redundancy of having both aircraft crews in a position where they
could observe and possibly avert an imminent collision?

That would require the airplane in position to turn towards approaching
aircraft and defeat the purpose of position and hold.

Presumably the purpose is to be able to respond quickly to a clearance
to take off. If the plane is angled but full power can still be
applied and the plane's path down the runway straightened out in the
first few seconds of the takeoff roll then no time would be lost and
the same purpose would still be achieved.

How is it that they were able to see the runway but not an airplane of 95'
wingspan and 82' length sitting on it?

People see what they expect to see. Same with hearing what they expect
to hear. Radio clearances have readbacks to protect against this, and
visual stuff have co-pilots to be a second opinion, but sometimes the
system breaks down. In this case, it broke down terribly.

Ben Hallert
PP-ASEL