Backup gyros - which do you trust?

Big John writes:

Sidney. All of the above G The approach plate gave the time to
field in minutes and seconds listing several speeds to accommodate
all the aircraft in inventory. Normally max time would only be 3-4
minutes and normally just 1-2 minutes after crossing cone of
silence. You rarely landed straight in and many of the headings to
field were not lined up with a runway. After sighting the field you
would circle and land on the active runway. If you were in radio
contact with the field/tower you could get surface wind and compute
a ground speed from cone of silence to field, other wise you made a
WAG from forecast and what you encountered en route.

This does not sound a lot different from a typical NDB approach today,
when the NDB is off the field.


All the best,


David

--
David Megginson, , http://www.megginson.com/

David

Wasn't, except you normally didn't have the option of tracking
outbound (on beam) from cone of silence like you can with ADF on a NDB
after station passage. You flew a heading and time for distance. Think
back on those days and shudder G

Big John

On Mon, 14 Jul 2003 12:14:01 GMT, David Megginson
wrote:

Big John writes:

Sidney. All of the above G The approach plate gave the time to
field in minutes and seconds listing several speeds to accommodate
all the aircraft in inventory. Normally max time would only be 3-4
minutes and normally just 1-2 minutes after crossing cone of
silence. You rarely landed straight in and many of the headings to
field were not lined up with a runway. After sighting the field you
would circle and land on the active runway. If you were in radio
contact with the field/tower you could get surface wind and compute
a ground speed from cone of silence to field, other wise you made a
WAG from forecast and what you encountered en route.

This does not sound a lot different from a typical NDB approach today,
when the NDB is off the field.


All the best,


David

Sydney Hoeltzli wrote
What do you think of the conclusions? They seem to be:
1) prevent AIs from failing

Well, there's a lot to be said for that. For one thing, it's far from
unlikely that BOTH of the AI's failed, not just one.

Did you miss this: (All quotes from the referenced report)

"These 21 artificial horizons had an MTBUR of 257 hours." That's mean
time before unscheduled replacement, but... "The artificial horizon
fitted to the EMB-110had no specified overhaul life and was treated as
an 'on condition'item" and thus all replacements were unscheduled.

Why was such a shockingly high failure rate tolerated? Well, "The
BCAR Section under which the aircraftwas certificated did not
stipulate the reliability requirementsthat the artificial horizon
should meet in order to ensure thatthe occurrence of a double failure
was a statistically remoteevent." Gotta love the way those regs
protect us...

And sure enough it was not statistically remote - it had happened
before! "An EMB-110 operated by another UK company suffered two
double artificial horizon failures in 1995. The first,on 4 June 1995,
involved a double instrument failure" There were only a handful of
EMB-110's in the UK...

2) since 2 AIs weren't enough to keep the plane upright (combined
with 2 turn and banks, 2 of every other instrument), require
passenger planes to have 3

Yes, that's the recommendation. IMO it's unmitigated crap. First
off, AI's should not be failing at an average of less than 300 hours.
Second, there were still two good PNI's (basically HSI's) and
turn&slip indicators. But could the pilots use them? Probably not
because "This technique, commonly referred to as 'limited panel' (see
paragraph 1.5.3.2) does not form part of a professional pilot's
recurrency training and testing."

So the most likely causes of the crash are AI failure (quite possibly
double AI failure), and the inability of the flight crew to fly
partial panel because SURPRISE they get no recurrent training in
partial panel flying. Exactly what kind of outcome could one expect
when you fit proven failure-prone AI's to an airplane and don't give
the flight crew any recurrent partial panel training?

(agree, chilling)

There are plenty of chilling accidents out there. This isn't one of
them. This was inevitable.

Michael

Big John wrote
Are you trying to tell me it's not easier to fly a PP NDB approach
than a PP ILS?

If she won't I will - and I've done both, for real, on the same night.
Flying the ILS was much easier.

I'd like to see you PP trying to use GPS to make an approach. It's
hard enough to keep the airplane flying PP without using the benefits
of GPS.

The last instrument student I taught could consistently fly a partial
panel GPS approach (with moving map) with the needle never leaving the
donut and with altitude control to +50/-0 ft without breaking a sweat.

I instructed for so many years in heavy iron I tend to push the
routines I developed to give maximum safety and yet perform the
mission.

Are you sure they're applicable outside heavy iron? I've never flown
any - all my flying and instructing has been singles and light twins
(with gliders thrown in for flavor) and I just can't see that a
partial panel GPS or ILS would be harder to fly than a partial panel
NDB. In fact, my proficiency approach for hoodwork is the night
partial-panel single-engine circling NDB, simply because that's the
most difficult. A single engine partial panel ILS to Cat II is cake
by comparison. Maybe ILS installations have improved...

Michael

Big John wrote:

The soft
(silk) white scarf made it easier to keep your head on a swivel like
they told you.

The British commanders would tell their newbies "It takes three seconds to
shoot down another aircraft. So look around every three seconds."

George Patterson
The optimist feels that we live in the best of all possible worlds. The
pessimist is afraid that he's correct.
James Branch Cavel

Michael

I was talking about basic PP; needle, ball and airspeed (normally
another word is used here G). If you only fault the AI then system
is easier to fly and we are closer together.

I also was throwing in the head movements to look at GPS (where ever
it is mounted) and then instruments on panel with the high probability
of vertigo. Also the communications required on a IFR instrument
approach divides your thought process and raises the difficulty. Many
people cannot do two things at the same time (fly and communicate
under pressure) and excel at both.

The basic key to safe IFR flight is good equipment and practice. The
more the better.

Also, some people take to IFR like a duck to water. Others struggle
and never become what I would describe as 'safe' even in benign Wx.

I have thousands of hours instructing in the Air Force plus
instructing GA pilots both SME on instruments so feel I have been
exposed to the best of both worlds. Techniques are not too different.

Fly safe

Big John


On 14 Jul 2003 14:57:48 -0700, (Michael) wrote:

Big John wrote
Are you trying to tell me it's not easier to fly a PP NDB approach
than a PP ILS?

If she won't I will - and I've done both, for real, on the same night.
Flying the ILS was much easier.

I'd like to see you PP trying to use GPS to make an approach. It's
hard enough to keep the airplane flying PP without using the benefits
of GPS.

The last instrument student I taught could consistently fly a partial
panel GPS approach (with moving map) with the needle never leaving the
donut and with altitude control to +50/-0 ft without breaking a sweat.

I instructed for so many years in heavy iron I tend to push the
routines I developed to give maximum safety and yet perform the
mission.

Are you sure they're applicable outside heavy iron? I've never flown
any - all my flying and instructing has been singles and light twins
(with gliders thrown in for flavor) and I just can't see that a
partial panel GPS or ILS would be harder to fly than a partial panel
NDB. In fact, my proficiency approach for hoodwork is the night
partial-panel single-engine circling NDB, simply because that's the
most difficult. A single engine partial panel ILS to Cat II is cake
by comparison. Maybe ILS installations have improved...

Michael

G.R.

The brit pretty well said it. Close to what I put up with as a newbe.

The old timers in my outfit however wanted you to keep your head
moving all the time (and got give a 3 second opening).

In the "finger four" we flew in, you didn't clear your own tail. One
of the other pilots in flight cleared your tail and you cleared his in
combat (loose) formation.

And the best.

Big John



On Mon, 14 Jul 2003 22:03:45 -0400, "G.R. Patterson III"
wrote:



Big John wrote:

The soft
(silk) white scarf made it easier to keep your head on a swivel like
they told you.

The British commanders would tell their newbies "It takes three seconds to
shoot down another aircraft. So look around every three seconds."

George Patterson
The optimist feels that we live in the best of all possible worlds. The
pessimist is afraid that he's correct.
James Branch Cavel

My big, ugly, AN horizon has been working reliably for decades... Makes you
kinda wonder...

Denny

"Michael" wrote in message
om...
Sydney Hoeltzli wrote
What do you think of the conclusions?

Big John wrote:

I also was throwing in the head movements to look at GPS (where ever
it is mounted) and then instruments on panel with the high probability
of vertigo.

If an IFR approach certified GPS requires extensive head movements
to follow the CDI, something went badly wrong in the install. The
CDI for an approach GPS should not require more head movements
than looking at any other CDI. In many installs, it *is* the same
CDI as nav radio.

Also the communications required on a IFR instrument
approach divides your thought process and raises the difficulty.

Very true, but wouldn't this apply no matter what approach is
being flown?

Cheers,
Sydney

"Sydney Hoeltzli" wrote in message
...
Michael wrote:

2) since 2 AIs weren't enough to keep the plane upright (combined
with 2 turn and banks, 2 of every other instrument), require
passenger planes to have 3

Yes, that's the recommendation. IMO it's unmitigated crap. First
off, AI's should not be failing at an average of less than 300 hours.
Second, there were still two good PNI's (basically HSI's) and
turn&slip indicators. But could the pilots use them? Probably not
because "This technique, commonly referred to as 'limited panel' (see
paragraph 1.5.3.2) does not form part of a professional pilot's
recurrency training and testing."

You Have Got To Be Kidding.

Are you serious? Yes, I missed that. Are they asserting this
shocking hole in proficiency training is widespread?

I think you're barking up the wrong tree here. Classic teaching of
partial/limited panel involves covering an instrument and then continuing to
fly without it. In the case of the Bandeirante accident, that wasn't the
issue. There was still a perfectly serviceable AI in the panel, and a pilot
sitting in front of it. The issue was identifying the failed instrument in a
complex cockpit environment.

The chances of being left with no working AI in the panel of a transport
aircraft (which starts with 3 AIs) but still having the instrumentation to
fly partial panel are so remote that it's not worth the time to train on it.
That time is better spent on other exercises, one of them *recognition* of
instrument failure.

For GA aircraft the situation is different. The probability of ending up
with a TC but no AI is much higher, and controlling the aircraft
successfully without it is easier. That makes it well worth the practice.

Julian Scarfe