Fllight Recorder Wars, Part II: What Backup to Use?

I'm currently using a Cambridge LNAV, a GPS/NAV model 20, and Pocket
NAV on a Compaq 1530. Last summer, I experienced my first flight
recorder hardware failure just before (thank goodness) a contest. So
I am looking at backup options. I'd like an add-on device; I have
neither the money nor the inclination for a complete
vario/computer/flight recorder transplant.

I've heard the arguments for/against various brands, technical
approaches, etc., for a primary flight recorder. I'm interested in
knowing what makes sense for a BACKUP GPS flight recorder that will:

1) act as a "dumb logger" (i.e., connect it to a separate battery,
switch on, and forget) for backup purposes

2) in the event of a failure of the primary flight recorder, could IN
FLIGHT be connected to my LNAV and/or Pocket NAV/Compaq WITHOUT
compromising the integrity of the record in the backup recorder. This
could involve swapping cables from one device to another (my current
GPS/NAV is accessible in the cockpit now) or making up a special "Y"
connector and/or switch.

I drove my LNAV with an early Magellan "fish finder" GPS receiver for
years before I bought the Cambridge flight recorder so I'm not averse
to carrying an independent backup flight recorder PLUS a cheap
handheld that could be powered up to provide GPS info to the LNAV
and/or PocketNAV for navigation.

Regarding navigation, I'm old fashioned enough that I can (and still
do) use a map. But today's start and finish cylinders, turn-area
tasks, stiff penalties for restricted airspace encroachment, and tight
final glides seem to demand some sort of moving map nav display.

Those of you who remember my tirades against manadatory flight
recorders years ago (despite assurances of their reliability) will
appreciate the irony of my predicament, as well as my reaction last
summer to (1) the technician's comment that he'd never seen my failure
mode before, and (2) the $350 repair bill.

My primary application is U.S. regional and national contests.

Will consider new or used. Thanks for any suggestions.

Chip Bearden

Chip,

What was the failure mode that you had?

It seems like you're almost asking for complete duplication of all your
systems, GPS, logger, and power, plus complete matrix switching across the
"network".

You need a switch upstream of your loggers that toggles between the data
streams between the two GPS data sources. You could configure it as a three
position switch:
1) GPS1 to LOG1 and GPS2 to LOG2
2) GPS1 to LOG1 and LOG2
3) GPS2 to LOG1 and LOG2

You could also use a NMEA sniffer that alarms a lost data stream so you can
make the switch (there is some allowance for loss of NMEA data stream, I
think).

For power, here's what I did. I run all the systems off my main battery. I
also have a smaller battery dedicated to the GPS source and data logger. If my
main battery fails, I switch to the backup. At least I get my data logged.

If you do a FMEA (Failure Modes and Effects Analysis), I bet you'll conclude
that the highest probability of failure is with the power system. Maybe you
just need some psycho therapy to get over your one failed relationship? ;-)



Jim Vincent
CFIG
N483SZ
illspam

Chip,

It just occured to me that for security reasons, the data logger has to be an
integrated unit where the GPS and logger are tied together in one package. So
switching GPS feeds would not work.

Just get a Volkslogger ( I think they're the least expensive) and a dedicated
2AH battery.

Jim Vincent
CFIG
N483SZ
illspam

A few points, which can be confirmed by looking at section 6.7.3 of the
US National Competition Rules:

1. A handheld GPS capable of recording altitude will provide acceptable
documentation at any US National or Regional contest.

2. An IGC secure flight recorder is required for primary documentation
for scoring that will count towards US team selection, but that doesn't
prevent you from using a non-secure recorder for secondary
documentation, if the primary recorder fails in flight.

I'd suggest a cheap handheld GPS with altitude recording capability as a
backup device, with a simple SPDT switch to allow selection of the
primary or secondary NMEA data source for the LNAV. KISS...

Marc

X-no-archive: yes
In article , Jim Vincent
writes
Chip,

It just occured to me that for security reasons, the data logger has to be an
integrated unit where the GPS and logger are tied together in one package. So
switching GPS feeds would not work.

Just get a Volkslogger ( I think they're the least expensive) and a dedicated
2AH battery.

Jim Vincent

While the Volkslogger is excellent kit is most respects, it has one
drawback. It is necessary to manually erase old flights to ensure there
is room to store new flights. When the memory becomes full, it stops
recording.

For this reason, it would be better to chose the Colibri which is
similar in size but overwrites old flights as necessary (Just like your
Cambridge).

Tim Newport-Peace

"May you be cursed with a chronic anxiety about the weather."

John Burroughs (1837-1921).

Chip,
I've just been through the same thought process. My recorder is a 302
connected to an IPAQ 3955 running WinPilot. The IPAQ has a compact
flash sleeve but also a built-in SD slot for a memory card to transfer
flight logs.
I bought a compact-flash GPS card on ebay for around $95 that will
lock onto satellites in around 10 sec. I haven't had a chance to try
this yet in the cockpit but here's the plan. If the 302 fails
recording I would insert the GPS card and reconfigure the IPAQ to read
the com port it is connected to. WinPilot will then record a (non
secure) .igc file and continue to give me navigation/final glide
information. I may want to carry a small AA battery driven power
supply for the IPAQ if the 302 fails providing the usual 5V.
Downsides a
a) you have to realize that your primary flight recorder is gone
b) fumbling around the cockpit reconfiguring the IPAQ
c) up to 2 minutes (or more) missing on your flight log
d) non-secure log not accepted in National Contests
It sure didn't cost me lot to get ready trying this!

Herbert, J7


(Chip Bearden) wrote in message . com...
I'm currently using a Cambridge LNAV, a GPS/NAV model 20, and Pocket
NAV on a Compaq 1530. Last summer, I experienced my first flight
recorder hardware failure just before (thank goodness) a contest. So
I am looking at backup options. I'd like an add-on device; I have
neither the money nor the inclination for a complete
vario/computer/flight recorder transplant.

I've heard the arguments for/against various brands, technical
approaches, etc., for a primary flight recorder. I'm interested in
knowing what makes sense for a BACKUP GPS flight recorder that will:

1) act as a "dumb logger" (i.e., connect it to a separate battery,
switch on, and forget) for backup purposes

2) in the event of a failure of the primary flight recorder, could IN
FLIGHT be connected to my LNAV and/or Pocket NAV/Compaq WITHOUT
compromising the integrity of the record in the backup recorder. This
could involve swapping cables from one device to another (my current
GPS/NAV is accessible in the cockpit now) or making up a special "Y"
connector and/or switch.

I drove my LNAV with an early Magellan "fish finder" GPS receiver for
years before I bought the Cambridge flight recorder so I'm not averse
to carrying an independent backup flight recorder PLUS a cheap
handheld that could be powered up to provide GPS info to the LNAV
and/or PocketNAV for navigation.

Regarding navigation, I'm old fashioned enough that I can (and still
do) use a map. But today's start and finish cylinders, turn-area
tasks, stiff penalties for restricted airspace encroachment, and tight
final glides seem to demand some sort of moving map nav display.

Those of you who remember my tirades against manadatory flight
recorders years ago (despite assurances of their reliability) will
appreciate the irony of my predicament, as well as my reaction last
summer to (1) the technician's comment that he'd never seen my failure
mode before, and (2) the $350 repair bill.

My primary application is U.S. regional and national contests.

Will consider new or used. Thanks for any suggestions.

Chip Bearden

If you want the absolute simplest backup (Primary for
those of us just out for some fun) solution to cover
all the capabilities of your 302(or whatever you have)
and Pocket PC running whatever you run, you can purchase
the Ique 3600 integrated Palm and Garmin GPS from Garmin
and run Soaring Pilot (www.soaringpilot.org), A great,
simple, and FREE final glide/?Navigation program by
Mark Hawkins or if you wait till 1 April when the Mitac
Mio 168 goes on sale in the U.S. (those of you in the
EU can already buy one). It is a Pocket PC all in one
PDA and GPS. SP writes IGC files and whatever software
you are capturing on your current PDA that you choose
to load on the Mitac will too!jeff

Hi Chip,

I have a biased opinion. I sell the Cambridge 302A GPS/logger. It is a
very nice unit. The price is the same as the VL and Colibri but it has much
more memory for flight logs (100 hours at 4 seconds) and waypoints (1500).
I've also been told by the UK Cambridge dealer that the 302A works great
with the L-NAV. I haven't tried that because I don't have my L-NAV anymore.
If it's true then the 302A is the only logger that would send destination
airport elevation to the L-NAV. That is a very nice feature. It would
therefore be possible to wire a switch to use either the GPS-NAV or the 302A
for input to your L-NAV.

Alternatively, the 302A can be used as a "dumb" logger. It requires only
the 12V connection and it will log for most or all of your soaring season.

The only disadvantage to the 302A is that it is a bit larger than a Colibri.
However, unlike a Colibri it can be mounted very nicely in a 57 mm
instrument panel hole.

I have them in stock for $895.

Good Soaring,

Paul Remde
Cumulus Soaring Supplies
http://www.cumulus-soaring.com


"Chip Bearden" wrote in message
om...
I'm currently using a Cambridge LNAV, a GPS/NAV model 20, and Pocket
NAV on a Compaq 1530. Last summer, I experienced my first flight
recorder hardware failure just before (thank goodness) a contest. So
I am looking at backup options. I'd like an add-on device; I have
neither the money nor the inclination for a complete
vario/computer/flight recorder transplant.

I've heard the arguments for/against various brands, technical
approaches, etc., for a primary flight recorder. I'm interested in
knowing what makes sense for a BACKUP GPS flight recorder that will:

1) act as a "dumb logger" (i.e., connect it to a separate battery,
switch on, and forget) for backup purposes

2) in the event of a failure of the primary flight recorder, could IN
FLIGHT be connected to my LNAV and/or Pocket NAV/Compaq WITHOUT
compromising the integrity of the record in the backup recorder. This
could involve swapping cables from one device to another (my current
GPS/NAV is accessible in the cockpit now) or making up a special "Y"
connector and/or switch.

I drove my LNAV with an early Magellan "fish finder" GPS receiver for
years before I bought the Cambridge flight recorder so I'm not averse
to carrying an independent backup flight recorder PLUS a cheap
handheld that could be powered up to provide GPS info to the LNAV
and/or PocketNAV for navigation.

Regarding navigation, I'm old fashioned enough that I can (and still
do) use a map. But today's start and finish cylinders, turn-area
tasks, stiff penalties for restricted airspace encroachment, and tight
final glides seem to demand some sort of moving map nav display.

Those of you who remember my tirades against manadatory flight
recorders years ago (despite assurances of their reliability) will
appreciate the irony of my predicament, as well as my reaction last
summer to (1) the technician's comment that he'd never seen my failure
mode before, and (2) the $350 repair bill.

My primary application is U.S. regional and national contests.

Will consider new or used. Thanks for any suggestions.

Chip Bearden

U.S. competition rules this year do not allow use of a PDA as a flight
recorder for flight documentation, even as a backup, unless the device
is IGC approved as secure. (P6.7.3)

-Dave Leonard

Herbert Kilian wrote:
Chip,
I've just been through the same thought process. My recorder is a 302
connected to an IPAQ 3955 running WinPilot. The IPAQ has a compact
flash sleeve but also a built-in SD slot for a memory card to transfer
flight logs.
I bought a compact-flash GPS card on ebay for around $95 that will
lock onto satellites in around 10 sec. I haven't had a chance to try
this yet in the cockpit but here's the plan. If the 302 fails
recording I would insert the GPS card and reconfigure the IPAQ to read
the com port it is connected to. WinPilot will then record a (non
secure) .igc file and continue to give me navigation/final glide
information. I may want to carry a small AA battery driven power
supply for the IPAQ if the 302 fails providing the usual 5V.
Downsides a
a) you have to realize that your primary flight recorder is gone
b) fumbling around the cockpit reconfiguring the IPAQ
c) up to 2 minutes (or more) missing on your flight log
d) non-secure log not accepted in National Contests
It sure didn't cost me lot to get ready trying this!

Herbert, J7


(Chip Bearden) wrote in message . com...

I'm currently using a Cambridge LNAV, a GPS/NAV model 20, and Pocket
NAV on a Compaq 1530. Last summer, I experienced my first flight
recorder hardware failure just before (thank goodness) a contest. So
I am looking at backup options. I'd like an add-on device; I have
neither the money nor the inclination for a complete
vario/computer/flight recorder transplant.

I've heard the arguments for/against various brands, technical
approaches, etc., for a primary flight recorder. I'm interested in
knowing what makes sense for a BACKUP GPS flight recorder that will:

1) act as a "dumb logger" (i.e., connect it to a separate battery,
switch on, and forget) for backup purposes

2) in the event of a failure of the primary flight recorder, could IN
FLIGHT be connected to my LNAV and/or Pocket NAV/Compaq WITHOUT
compromising the integrity of the record in the backup recorder. This
could involve swapping cables from one device to another (my current
GPS/NAV is accessible in the cockpit now) or making up a special "Y"
connector and/or switch.

I drove my LNAV with an early Magellan "fish finder" GPS receiver for
years before I bought the Cambridge flight recorder so I'm not averse
to carrying an independent backup flight recorder PLUS a cheap
handheld that could be powered up to provide GPS info to the LNAV
and/or PocketNAV for navigation.

Regarding navigation, I'm old fashioned enough that I can (and still
do) use a map. But today's start and finish cylinders, turn-area
tasks, stiff penalties for restricted airspace encroachment, and tight
final glides seem to demand some sort of moving map nav display.

Those of you who remember my tirades against manadatory flight
recorders years ago (despite assurances of their reliability) will
appreciate the irony of my predicament, as well as my reaction last
summer to (1) the technician's comment that he'd never seen my failure
mode before, and (2) the $350 repair bill.

My primary application is U.S. regional and national contests.

Will consider new or used. Thanks for any suggestions.

Chip Bearden

Good comments so far. Thanks. A few points:

1. The backup device MUST produce a log that's acceptable for U.S.
regional and national contests. As I read the rules, a handheld GPS
receiver is acceptable--even for a U.S. nationals--so long as it logs
altitude; a PDA-based system with a GPS card is not.

2. The most likely failure mode may well be a power problem, but I've
already got a backup power supply (that I've used 3 or 4 times over
the past 30+ years for genuine failures).

3. Regarding failure of the flight recorder:
a) the probability may be low but it's already happened once (the
UART comm. chip, I was told); to date, that's at least as frequent as
a power supply failure on a per hour or per flight or per year basis
b) the EFFECT is disastrous; if I'm going to drive halfway across
the country and spend the money to enter a nationals, I don't want to
zero a day because some $2 part fails. That's like tossing a live .45
caliber shell into a bin with 99 blanks, mixing them up, then picking
one at random, loading it into a pistol, aiming it at my head, and
pulling the trigger. The percentages are in my favor but the
consequences of that 1% chance are severe.

4. I can live without certain navigation and flight computer features
(I still carry a current sectional and a cardboard final glide
calculator) but if there are several alternatives and one allows me to
switch the source of GPS info for my LNAV and PocketNAV from my
Cambridge 20 to the backup device quickly and easily, it makes the
choice easier.

5. Gaps of up to 15 minutes are allowed, as are multiple incomplete
flight logs. So there is time to switch from one device to another so
long as (i) the primary flight recorder retains the flight log for the
portion of the flight preceding the failure point (not true,
apparently, when mine failed last year) OR the backup device has been
logging the flight from takeoff.

To date, Paul Remde's suggestion of a Cambridge 302A sounds easiest
(though not cheap). But that raises the same questions about
Cambridge's long-term (or even short-term) survival as were discussed
on this forum last year. What's the latest?

Chip Bearden