From: Mary Shafer <shafer@orville.dfrc.nasa.gov>
Newsgroups: sci.space.shuttle
Subject: Re: CNN's Miles O'Brian; SHADDDAP!!
Date: 25 Oct 2000 09:36:07 -0700

Markus Mehring <m.m@gmx.net> writes:

> On Tue, 24 Oct 2000 21:12:54 GMT, kodostheexecutioner@my-deja.com wrote:
>
> >Bad enough I don't get NASAtv, but to have to listen to this dolt
> >yapping all the way thru the landing, over the PAO and the calls to and
> >from Discovery just pisses me off.

> Sheesh, what did you miss? A syllable or two? He did his job, which
> includes "filling blanks". You sure did notice his repeated tries of
> "let's listen in", and then there was nothing to listen in to,
> because neither Discovery nor Houston nor PAO said a significant
> word?

The reason that no one says much is based on a concept the FAA imposed
on the airlines after there was a fatal crash because the pilots were
so busy chatting about the other aircraft at the airport that they
messed up the checklist and tried to take off in the wrong
configuration (no flaps, I think).  It's called "sterile cockpit" and
it's designed to keep the crew's mind on flying and nothing else.
During takeoffs and landings, there's no conversation allowed in the
cockpit that isn't directly about the evolution and external
interruptions are severely limited.  ATC doesn't make a lot of calls
and the flight attendents aren't calling or knocking on the door.  The
sterile cockpit has become pretty standard in military operations,
too.  We've picked it up around here, although I don't know if we have
a formal policy on it or if it's just a consensus thing.

In addition, some of it goes back to the early flights, before the FCS
was updated, when the system was so touchy that just holding down the
mike button could overload a pilot into a PIO.  Actually, the Orbiter
wasn't that bad after we put the PIOS filter into it, but when we
duplicated some of the flaws that increase PIO proneness in research
aircraft, we did find that asking the pilot to give us a Cooper-Harper
and PIO rating, with explanation, was so much increase in workload
that, even with the PIOS filter working, the plane would start
diverging, only to stop when the pilot took his finger off the mike
button (and without the filter, the plane would be off to the races).
Anyway, when they land, the astronauts don't like to hang onto the
RHC, meaning they don't like to hold down the mike button, so they're
not very chatty.

--
Mary Shafer
shafer@orville.dfrc.nasa.gov Of course I don't speak for NASA
Senior Handling Qualities Research Engineer
NASA Dryden Flight Research Center, Edwards, CA
For non-aerospace mail, use shafer@spdcc.com please

From: Mary Shafer <shafer@orville.dfrc.nasa.gov>
Newsgroups: sci.space.shuttle
Subject: Re: CNN's Miles O'Brian; SHADDDAP!!
Date: 25 Oct 2000 16:51:19 -0700

"Jim  Nowotarski" <jimn@worldnet.att.net> writes:

> "Mary Shafer" <shafer@orville.dfrc.nasa.gov> wrote in message
> news:u04s207ua0.fsf@orville.dfrc.nasa.gov...
>
>
> > duplicated some of the flaws that increase PIO proneness in research
> > aircraft, we did find that asking the pilot to give us a
> Cooper-Harper
>
> Well, I know that PIO is Pilot Induced Oscillation, but what's a
> Cooper-Harper?

It's a pilot opinion rating scale used in handling qualities
evaluations.  Pilots walk through a decision tree and assign
numerical ratings to the way the aircraft performs in specified tasks.
The scale goes from 1 (a perfect airplane) to 10 (pilot won't
fly it again until it's fixed) and measures pilot workload and the
requirement for pilot compensation techniques.  It was created by
George Cooper of Ames Research Center and Bob Harper of Cornell Aero
Labs/Calspan/Veridian in the '50s.

The PIO rating scale came out of the F-4H acceptance testing and was
patterned on the Cooper-Harper rating scale, with a decision tree used
to produce a numerical rating.  It's a little more objective, being
based more on what the airplane is doing, compared to the
Cooper-Harper scale, which is based more on what the pilot's doing in
reaction to the airplane.

However, both of these numerical ratings, while useful in their way,
are meaningless without the pilot comments that accompany them.  We
often give the pilot a questionnaire to go through to structure the
comments, to be sure that we know why a particular rating is assigned.
For example, one airplane could be a CHR 4 because it's sluggish and
another could be a CHR 4 because it reacts too quickly and yet another
could be a CHR 4 because the pilot has to change the normal way of
making inputs to accomplish the task.  If all we had were the three 4s
we wouldn't know what caused them, but with the comments we can
pinpoint the problem.

Well-trained test pilots are remarkeably consistant in the ratings
they give, by the way.  When the ratings are plotted, the points
cluster fairly tightly, rather than looking like a shotgun plot.
Actually, this consistancy isn't limited to test pilots, as
researchers at Ames have shown that airline pilots, given good
briefings on the use of the rating scale, are also very consistant.

The tasks we ask pilots to do when they're rating airplanes are
high-gain precision tasks.  Tight formation, precision touch-and-goes,
guns tracking, pitch and bank angle captures, simulated ground attack
are a few I can think of quickly.  The reason we use such tasks is
because almost every airplane is fairly good in cruise; it's only when
the pilot has to make the plane do something precise and difficult
that the flaws show up.  In addition, we know enough about what makes
aircraft good and bad that we have predictable ways of changing the
way the aircraft responds, so we can use variable-stability aircraft
for handling qualities research.  In addition, the data used for these
predictions is also used to create criteria that manufacturers design
to, and these criteria are MIL-SPEC 8785C and MIL-PRIME 1787B for
military aircraft.  For civil aircraft the numbers are embedded in the
FARs.

--
Mary Shafer
shafer@orville.dfrc.nasa.gov Of course I don't speak for NASA
Senior Handling Qualities Research Engineer
NASA Dryden Flight Research Center, Edwards, CA
For non-aerospace mail, use shafer@spdcc.com please