PowerFlarm Warnings Display Comparison

On Saturday, November 22, 2014 9:03:18 PM UTC-6, son_of_flubber wrote:
On Saturday, November 22, 2014 5:15:04 AM UTC-5, Z Goudie wrote:

Remember, if you're flying too slowly into a strong headwind in wave and
thus proceeding backwards over the surface of the earth, when Flarm calls a
conflict at 12 o'clock it's behind you....

So more generally, 12 o'clock on the Flarm warning circle aligns with bearing rather than heading?

OK, time for some basic FLARM theory:

FLARM uses GPS and pressure altitude exclusively; it has no heading input. So the warnings it sends are based on pressure altitude, GPS position and GPS track - and it assumes you are moving forward. It has no way of knowing which way your fuselage is pointing.

So FLARM warnings are aligned to your TRACK, not your HEADING. And in most cases, this is sufficient, as you are not trying to nail down a bearing to another glider within a few degrees - each clock sector is 30 degrees, remember.

That's why a FLARM display on a moving map (like an Oudie) is nice - it will be based on the GPS position of the other FLARM equipped gliders, so even if you are backing up in wave, it will show their true position relative to you (although, you will appear to be flying backwards on your Oudie!).

So, to summarize, the displayed BEARING to a FLARM target is referenced to your TRACK, not your HEADING, so if there is a lot of drift due to wind, you will have to compensate for it.

(Any FLARM-smarter guys out there, please correct me if I have got it wrong!)

Kirk
66

On Saturday, November 22, 2014 2:36:38 AM UTC-6, Richard wrote:
On Friday, November 21, 2014 7:42:53 PM UTC-8, Ramy wrote:
On Friday, November 21, 2014 3:30:50 PM UTC-8, Sean Fidler wrote:
Great stuff! Thanks!!!

Slightly of topic but I wonder why we are still using clock to tell directions. Yeah it sounds cool but is it really necessary?
In the age of digital clocks, it takes time for most people to interpret it. Case in point is tow pilots. I noticed about 20% of tow pilots turning opposite direction when I say for example turn to 9 oclock instead of turn left. The rest take few long seconds to interpret.
How about front, back, left, right, front left, back right etc, similar to car GPS? Or 20 degrees left etc? Yeah I know its not perfect either and some people mix left and right as well, but maybe something to consider.

Ramy

I sort of agree. The first time I heard the lady my reaction was where is that. I had not looked at a hand clock for at least 15 years. But after some use it came back.

Richard
www.craggyaero.com

True story:

Back in the days of diesel powered fighters with steam driven radars (F-4s, to those too young to remember), when one of the crewmembers called out a target to the other (F-4 is a two-seater, pilot in front rowing the boat, and WSO in the back shooting the ducks...), it was standard technique to use both left/right AND clock position, to avoid any confusion; so a call might be "OK I've got a tally on the bandit at left 8 o'clock, nose low, closing - come hard left!"

Inevitably, during a debrief of a fight while listening to the cockpit tapes, we heard this exchange: "I've got him! He's at Right 9 o'clock!" "You mean Left 3?" "No! Over there!!!"

Shortly followed by a "Guns tracking on the F-4 rocking his wings...." call..

Seriously, clock positions make a lot more sense than just left/right - as they devide the area to search into nice little unambiguous 30 degree sectors of sky. How do you do that with Left/Right (or Port/Starboard)?

Kirk
66

On Saturday, November 22, 2014 9:04:37 AM UTC-8, kirk.stant wrote:
Seriously, clock positions make a lot more sense than just left/right - as they devide the area to search into nice little unambiguous 30 degree sectors of sky. How do you do that with Left/Right (or Port/Starboard)?

Kirk
66

Okay, since you asked for it.

Ahead
Ahead right
Right
Behind right
Behind
Behind left
Left
Ahead left

45 degree sectors

If you want more precision:

Ahead
Ahead ahead right
Ahead right
Right ahead right
Right
Right behind right
Behind right
Behind behind right
Behind
Behind behind left
Behind left
Left behind left
Left
Left ahead left
Ahead left
Ahead ahead left

22.5 degree sectors.

Of course if you use this over the radio for a position callout you are most likely to get a WTF in reply - maybe better to learn the clock.

;-)

Clearnav allows personalized alerts. You can replace the wav files with whatever works for you. Highly recommended!

For example, my 5 o'clock low alert is "traffic, right side, down low, 5 o'clock". It gets me looking right with no delay, down and then finally I scan forward or back based on the clock verbiage but I'm already immediately looking in the right general direction based on the first two audibles.

I would estimate (at least for me) that it reduces the time to pinpoint where to look by half. Course I still struggle with the big hand and the little hand so your mileage may vary.

On Saturday, November 22, 2014 1:36:57 PM UTC-8, wrote:
Clearnav allows personalized alerts. You can replace the wav files with whatever works for you. Highly recommended!

For example, my 5 o'clock low alert is "traffic, right side, down low, 5 o'clock". It gets me looking right with no delay, down and then finally I scan forward or back based on the clock verbiage but I'm already immediately looking in the right general direction based on the first two audibles.

I would estimate (at least for me) that it reduces the time to pinpoint where to look by half. Course I still struggle with the big hand and the little hand so your mileage may vary.

Please provide us with a Video so we can evaluate.

Richard
www.craggyaero.com

On Saturday, November 22, 2014 4:36:57 PM UTC-5, wrote:
Clearnav allows personalized alerts. You can replace the wav files with whatever works for you. Highly recommended!

For example, my 5 o'clock low alert is "traffic, right side, down low, 5 o'clock". It gets me looking right with no delay, down and then finally I scan forward or back based on the clock verbiage but I'm already immediately looking in the right general direction based on the first two audibles.

I would estimate (at least for me) that it reduces the time to pinpoint where to look by half. Course I still struggle with the big hand and the little hand so your mileage may vary.

But you still gotta know the clock to name the .wavs correctly :-)

Here's a 30 second clip of Flarm warning on CN. CN supplies the voice, the beeping you hear is from a Butterfly 57mm display that's also in my panel.

https://www.youtube.com/watch?v=APMTBfz6XZ0

-Evan Ludeman for CNi

- maybe better to learn the clock. ;-)

Considering that some schools in our area are not teaching cursive writing and I recently came across some kids 15 years old who can't do their own signature, this may be a stretch.... sigh