Revised IGC-approvals for some types of legacy recorder

Marc Ramsey wrote:
In any case, a number of people with expertise
in the area have argued rather convincingly that the relationship
between pressure altitudes measured above 32,000 feet or so and actual
elevation above the ground is tenuous, at best.

Of course, I meant "actual elevation above sea level"...

Marc

On Thu, 20 Nov 2003 06:20:57 GMT, Marc Ramsey wrote:

Mike Borgelt wrote:
So you feed a pressure sensor to the computer controlling the GPS
pseudolites and it roughly matches with GPS altitudes with appropriate
corrections for reasonable guesses as to the mean temperature in the
atmosphere. Dead easy! And a trivial enhancement to your pseudolite
system. Given that some IFR aviation GPS systems already use pressure
altitude for GPS aiding it would not surprise me if test equipment
that can do all this isn't available off the shelf.

When is the demo going to be ready? 8^)

Easier to just break in to the logger and install the switchable IR
link. Trivial. Mickey mouse microswitches just don't do it. The
professionals use thermite.


Why limit the change to geometric altitude to above 32K feet? Most
loggers are on cockpit static (an original adamantly insisted on
requirement by GFAC now changed I believe - why?). That is good for 50
to 100 feet of error, you get sea level pressure changes and huge
errors due to temperature in the atmosphere, let alone running the
pressure sensors at maybe -20 C or colder. The fully approved
Volkslogger only claims +/- 2hPa over temperature which is another
+/-100 feet at around 20,000. You are already over any reasonable GPS
error budget.

The IGC works in mysterious ways. It seems eminently sensible to me to
switch completely over to GPS measured geometric altitude, but I don't
get to make the rules. In any case, a number of people with expertise
in the area have argued rather convincingly that the relationship
between pressure altitudes measured above 32,000 feet or so and actual
elevation above the ground is tenuous, at best.

I believe that was calculated before SA was turned off. As I pointed
out above I doubt very much that any cockpit static can be better
than 50 to 100 feet.Static ports on gliders are sometimes pretty
terrible too so may not be any better. Try a good side slip and see
what happens also.
Add in the other error sources and you are worse than GPS altitude at
any altitude much above 1000 feet AGL.


ISA day sea level 1000 feet pressure altitude, geometric altitude 1000
feet
Try sea level 45 degrees C with DALR and a pressure altitude of 1000
feet. Mean temperature of layer is 43.5 geometric altitude 1102 feet

102 feet error! GPS is at least as good as this most of the time.


The reason for the change allowing panel mounted flight recorders to use
aircraft static as an alternative to cockpit static is very simple. An
instrument manufacturer requested the change, and persuaded us that the
original reasoning behind the requirement for cockpit static was no
longer relevant.

Then again neither the original reasoning nor the persuasion seems to
have seen the light of day.

Do you realise that the original requirement drove some serious system
architecture considerations for manufacturers? As I said the GFAC were
originally adamant about no static connections - what changed their
minds?
How does anyone trust the rules when they may change next week?
Nothing I've seen written here convinces me that anyone on GFAC has a
clue.

Mike Borgelt

Mike Borgelt wrote:
I believe that was calculated before SA was turned off. As I pointed
out above I doubt very much that any cockpit static can be better
than 50 to 100 feet.Static ports on gliders are sometimes pretty
terrible too so may not be any better. Try a good side slip and see
what happens also.
Add in the other error sources and you are worse than GPS altitude at
any altitude much above 1000 feet AGL.

It isn't a question of accuracy, it's a question of what is being
measured. Some believe we should continue to measure pressure altitude,
simply because that's what we've always done. I think it safe to say
that is now recognized by the IGC that once you get into the tropopause,
the magnitude of the error goes up rapidly. The current world altitude
records can't really be said to measure altitude, they simply measure
record low pressures.

Then again neither the original reasoning nor the persuasion seems to
have seen the light of day.

Frankly, GFAC is pretty much like every other committee I've been
involved with. Decisions aren't necessarily made by reason or
persuasion, they often are made by something approximating the consensus
when everyone gets tired of discussing it. After a few years, it's
often difficult to figure out exactly why a particular decision was made.

Keep in mind, there is no secretary, no meeting notes. Just a few
people spread out over a couple of time zones, many of whom have never
met any of the others face to face. 95% of the communication that goes
on is over email, and there's is no central archive. Perhaps if there
was a more sizable budget and actual salaries, we could communicate to
all with the level of detail and consistency you seem to be expecting.
But, for the moment you are stuck with a bunch of volunteers, some of
whom have been putting up with this sort of grief for 10 years now.

Do you realise that the original requirement drove some serious system
architecture considerations for manufacturers? As I said the GFAC were
originally adamant about no static connections - what changed their
minds?

Yes I do realize that. Just as I'm sure you realize that the concept of
flight recorders was very new in 1995, and that there has been a steep
learning curve for all involved. You also realize that the makeup of
GFAC now is quite different than it was in 1995. And, of course you are
fully aware that people can change their attitudes about issues over time.

How does anyone trust the rules when they may change next week?

The rules don't change every week. Rule changes are proposed at the IGC
meeting each March. Those rule changes that are accepted at the meeting
go into effect the following October. The manufacturers of approved
flight recorders (and those who have notified us that they intend to
submit a recorder for approval) are nearly always given advanced
notification (nobody is perfect, except you apparently) of proposed
changes, and asked for their input.

Nothing I've seen written here convinces me that anyone on GFAC has a
clue.

Well, at least we don't sit around badmouthing you on r.a.s.

Marc

Mike Borgelt wrote:

Not at all. Are you seriously suggesting that you can break a World
Record at essentially no notice on Sunday afternoon at your local
gliding club? Lots of luck.

yes I do ! Look at this one :

FAI has received the following Class D (Gliders) record claim :
================================================== ==============
Claim number : 7983
Sub-class DO (Open Class Gliders)
General Category
Type of record : Speed over a triangular course of 100 km
Course/location : Fremont County Airport, Canon City, CO (USA)
Performance : 243.41 km/h
Pilot : Tom K. SERKOWSKI (USA)
Glider : Schleicher ASH 26E
Date: 09.11.2003
Current record : 234.95 km/h (07.05.2000 - James M. PAYNE, USA)
================================================== =============

Tom had been doing his annual inspection on Saturday, his rigged on
Sunday morning and took off for a check flight, which happenned to be a
world record !


Nowadays it takes much preparation and planning which will take you
much longer than 30 days. It isn't at all unreasonable to require
prior notice of intention.

I don't say that he did not prepare this flight for a long time, but he
certainly could not have noticed FAI 30 days before than he would be
attempting a record that particular day. And I say again that you cannot
forcast a wave situation 30 days in advance.

I you just suggest that any pilot willing to attempt a record make a
notice without mentioning the exact date, it's like doing nothing... or
you can notice FAI each day for the following 30th day that you will
attempt a record, by some sort of automatic mailer, not to miss THE good
day, but I don't see any interest neither.


--
Denis
Private replies: remove "moncourrielest" from my e-mail address
Pour me répondre utiliser l'adresse courriel figurant après
moncourrielest" dans mon adresse courriel...

Mike Borgelt wrote in message . ..

"O.O to use his own PC to clear logger memory before takeoff then seal
the loggers in aircraft no more than 15 minutes before takeoff. O.O
notes takeoff and landing times."

This proposal would eliminate the one remaining approved Cambridge
logger. To the best of my knowledge there is no means for an OO to
clear the memory of a 302.

Andy Durbin (GY)

Um, I did just that last December 15, and again on the 9th of this
month. I flew a 100km triangle from one of my local fields without
much preparation to speak of:
Winds forecast looked favorable a couple days before and I was
scheduled to assemble the ship for the annual inspection. After the
inspection I declared 100k triangle for grins and flew it at 151.25
mph. (234.95 km/h)

On the Dec 15th flight, I was just going up for some local fun
soaring, but since wave was working, I declared 100k as a state record
attempt and it turned into a US record. It was faster thatn the world
record but not by the 2 km/h margin required for a claim.

There's still a few world records out there that could be done 'on a
whim' if one happens to be in the right place at the right time.

-Tom

Mike Borgelt wrote in message . ..

Not at all. Are you seriously suggesting that you can break a World
Record at essentially no notice on Sunday afternoon at your local
gliding club? Lots of luck.

Take a look at the effort that Steve Fossett and others are going to.

Nowadays it takes much preparation and planning which will take you
much longer than 30 days. It isn't at all unreasonable to require
prior notice of intention.

It has nothing whatever to do with weather forecasters (and I am one
-or used to be).

Mike Borgelt

On Thu, 20 Nov 2003 12:00:38 GMT, Marc Ramsey wrote:


The rules don't change every week. Rule changes are proposed at the IGC
meeting each March. Those rule changes that are accepted at the meeting
go into effect the following October. The manufacturers of approved
flight recorders (and those who have notified us that they intend to
submit a recorder for approval) are nearly always given advanced
notification (nobody is perfect, except you apparently) of proposed
changes, and asked for their input.


Marc,

I suggest you seriously research the history of what happened in 1995
to 1997. The IGC had rules in place for loggers which GFAC blatently
defied when it came to approval. The rules were then changed quite
outside the system you talk about. It is a matter of public record. I
suggest you contact Robert Danewid and EW Avionics privately and
publish your apology here later.

Mike Borgelt

Mike Borgelt wrote:
I suggest you seriously research the history of what happened in 1995
to 1997. The IGC had rules in place for loggers which GFAC blatently
defied when it came to approval. The rules were then changed quite
outside the system you talk about. It is a matter of public record. I
suggest you contact Robert Danewid and EW Avionics privately and
publish your apology here later.

Mike,

I am quite willing to discuss technical issues with respect to the
current flight recorder specifications. I am also willing to discuss
what might be done to improve the specifications in the future. All I
know of what went on in the '95 to '97 time frame is what was discussed
in r.a.s. at the time. I have no interest in rehashing it now.

Marc

In article , Mike Borgelt
writes

snip

I suggest you seriously research the history of what happened in 1995
to 1997. The IGC had rules in place for loggers which GFAC blatently
defied when it came to approval. The rules were then changed quite
outside the system you talk about.

I do not wish to get into further argument with Mike Borgelt but I must
point out that the interpretation above is his own. It is certainly not
mine or that of GFAC or IGC since they oversee GFAC and review the GFAC
annual report to IGC at each plenary.

He refers, I think, to the process that resulted in the "IGC Badges up
to and including Diamonds" level that was applied to the EW series of
recorders that do not have their own GPS but must be connected by cable
to one of the Garmin range of GPS receivers. And would have probably
applied to the Borgelt Joey recorder had he submitted an IGC version for
IGC-approval.

Mike, I do not want to get involved in a slanging match or indeed to
reply further. But for those who are new to this, I really had to
comment on your statement above in case people thought that it was the
only interpretation of early events in the IGC-approval process. I do
not doubt that it is yours, but it may not be other's.

The dates of all IGC-approvals including historic ones is on the
gliding/gnss web site and the history up to the issue of the EW
IGC-approval is:

16 Jan 96 - Cambridge Models 10, 20 and 22, initial issue

31 May 96 - Peschges VP8, initial issue

12 Aug 96 - Filser LX20, initial issue

10 Nov 96 - Zander GP940, initial issue

20 Mar 97 - Print Technik GR1000, initial issue

25 Mar 97 - Filser LX20 Version 2 Approval, with the addition of motor
glider engine recording

19 Apr 97 - EW "EWFR A & B" for badge flights up to and including
Diamonds, when connected by cable to one of a list of approved GPS
units, listed in the IGC-approval document.

etc., for more details see:

http://www.fai.org/gliding/gnss/igc_approved_frs.pdf

--
Ian Strachan
Chairman, IGC GNSS Flight Recorder Approval Committee (GFAC)



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