178 seconds -- the facts about the experiment

From [email protected] Thu Oct 31 23:41:04 2002
Path: news.redhat.com!news-reader.ntrnet.net!newsfeed.zip.com.au!newsfeed.hostname.nl!newsfeed01.sul.t-online.de!t-online.de!newspeer1-gui.server.ntli.net!ntli.net!newsfep2-win.server.ntli.net.POSTED!53ab2750!not-for-mail
From: "Julian Scarfe" <[email protected]>
Newsgroups: rec.aviation.student,rec.aviation.piloting
Subject: 178 seconds -- the facts about the experiment
Lines: 115
X-Priority: 3
X-MSMail-Priority: Normal
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000
Message-ID: <[email protected]>
Date: Wed, 30 Oct 2002 16:41:37 -0000
NNTP-Posting-Host: 80.2.246.217
X-Complaints-To: [email protected]
X-Trace: newsfep2-win.server.ntli.net 1035996067 80.2.246.217 (Wed, 30 Oct 2002 16:41:07 GMT)
NNTP-Posting-Date: Wed, 30 Oct 2002 16:41:07 GMT
Organization: ntl Cablemodem News Service
Xref: news.redhat.com rec.aviation.student:42140 rec.aviation.piloting:71704

I can't remember the thread where it recently came up but the subject of VFR
into IMC and the "178 seconds" article frequently crops up on rec.aviation.

http://www.aviation.uiuc.edu/institute/research/arl/technical-reports/178Sec
ondstoLive.html

A Google search reveals dozens of pages with variants of the article on.

I was sufficiently intrigued by the experiment described that I contacted
UIUC, which is cited in the article as responsible for the research, since I
couldn't find the paper on the WWW.  UIUC's Institute of Aviation staff were
very helpful, and two days later I had a copy of the original research paper
on my desk.  Thanks to Mary and Ted there for their helpful and prompt
response.

The following is a summary of some key points of the paper itself, entitled
"180-degree turn experiment" and in UI's Aeronautics Bulletin 11.  I have no
axe to grind, and I think the "178 seconds" article does a good job of
communicating the hazards of spatial disorientation.  However, some issues
have become clouded by the "chinese whisper" effect, so this is to set the
record straight.

* The research was conducted at University of Illinois Institute of Aviation
in 1954, principally by Jesse Stonecipher, the CFI.

* It was a response to the challenge from AOPA to devise a technique for
non-instrument rated pilots who had flown inadvertently into IMC

* The tests were conducted on a Beech Bonanza C-35 in flight (not a "ground
trainer" as cited in the 178 Seconds article)

* The 20 subjects for the experiment were chosen for being representative of
those pilots who had *no* simulated or actual instrument experience (not
"none since primary training", none at all)

* The Bonanza was chosen specifically *because* it would be difficult to
fly, as the most complex single that a non-IR pilot was likely to fly.

* None of the subjects had soloed a Bonanza.  As far as I can tell, only 3
of the subjects had any complex experience at all, with most of them
recording time on Aeronca 7AC, Cessna 140 and Tri-Pacers.

* Most of the subjects had only about 20 hours dual time, presumably the PPL
syllabus in those days.  7 of them had less than 40 hours total.

* The aircraft was made to simulate basic VFR instruments, plus a turn
indicator.  The AI, DG and rate of climb indicators were covered for the
entire experiment.

* The first period of the experiment was the famed '178 seconds' test, aimed
at assessing the students' baseline instrument aptitude.  The time was
measured between the googles being placed over the students' eyes and an
'incipient dangerous flight condition'.  For most cases this was deemed to
be an airspeed of 185 mph or an incipient stall.

*  19 of the 20 went into a 'graveyard spiral'.  One pulled the aircraft
into a whip-stall.

* Times ranged from 20 seconds to 480 seconds.  The average was indeed 178
seconds

* There then followed 4 periods of instruction in the 180 degree turn
technique (see below) that was the actual subject of the study

* By the end of this training, the subjects had between 1.5 and 3 hours
(mean 2 hours) simulated IF, practising the technique.

* The subjects were again tested by simulating instrument conditions, and
asked to transition from cruise to slow flight, make a 180 degree turn, and
establish a controlled descent. Each subject was tested 3 times.

* Of the 60 trials, 59 were successfully completed.  The unsuccessful one
involved the failure to set power to maintain altitude and continued the
descent in a way that violated the success definition.  It was considered
that control was not lost, and that if the aircraft had not become visual
below cloud, the impact would have been survivable.

The technique:

Throughout, center the turn needle using the rudder.
1) Hands off the control column
2) Lower the landing gear
3) Reduce power
4) Set trim to a predetermined position for slow flight (95 mph)
5) Adjust prop and power for approx level flight at 95 mph
6) Note the compass heading
7) Turn using the rudder
8) Roll out with appropriate lead or lag
9) Center the turn needle
10) Reduce power for a controlled descent

It was noticed that step 1 was both the most important and the most
difficult psychologically!

The usual deduction from the 178 Seconds article is the rather negative one
that pilots without instrument training are in big trouble if they enter
IMC.  I think the message that Stonecipher was trying to convey (and the
result speak for itself!) is much more positive, that a little instument
training can go a long way, even if faced with a partial panel and a complex
aircraft.

Julian Scarfe
[email protected]