Compass erroprs

Come on in for general chat and POLITE banter between LAA members

Moderators: John Dean, Moderator

ROB. THOMASSON
Posts: 129
Joined: Mon May 14, 2012 5:36 pm

Compass erroprs

Post by ROB. THOMASSON » Sat Feb 17, 2018 8:09 am

A friend of mine was flying a passenger the other day who had a protective case for his smart phone. The snag is this was held shut with a magnet. So you've worked out the rest of it haven't you! So watch out for this pitfall and keep items off the top off the panel.
027506

dmcnicholl
Posts: 93
Joined: Sun Feb 14, 2010 8:25 pm

Re: Compass erroprs

Post by dmcnicholl » Sat Feb 17, 2018 8:37 am

Even without the magnetic case closure I'm pretty sure the phone itself will produce a similar result. I considered adding a smart phone at TDC (single seater) to use as a PAW radar display but it badly affected the compass just below.
Donald McNicholl
006054

PaulSS
Posts: 43
Joined: Wed Mar 15, 2017 6:04 am

Re: Compass erroprs

Post by PaulSS » Sat Feb 17, 2018 11:56 pm

I can't help but wonder why we (UK) still insist on equipping the aircraft with a compass. Sure, if it's your thing and you want to, then go ahead but mandating the fitment just seems daft to me.

My panel design has an EFIS and an iPad, both of which will show me my magnetic track (which is all we're really interested in to navigate) down to decimals of a degree if I so wish. If the power fails to the EFIS then the iPad will be fully charged and will still be running hours after I've landed the aircraft and gone home. I can fit a magnetometer and have magnetic heading on the EFIS but that doesn't count; I still have to fit something that Nelson would have been proud of for my day, VFR flying :shock:

Sitting in my pocket is a smart phone with all manner of compass indications available to it, even if I don't install a navigation app. It is no less accurate than the thing which will sit atop my panel but probably more useful as it doesn't bounce and swing around all over the place and sway +/- 10 degrees in light turbulence. I find it absolutely bizarre that these bits of kit have to be swung to within a gnat's tadger but then are barely useable in reality to within +/- 5/10 degrees. Not that I will ever look at it, when I've got kit that tells me what I'm actually doing, instead of relying on a wind forecast and a dubious indication of my magnetic heading :roll:

Before someone pipes up with the mocking and trite phrase of 'children on the magenta line', you should know that I did learn to navigate with a map and stopwatch (and then used the same in military fast jet operations) some considerable time before GPS made its way into our cockpits, so I am more than capable of using a compass and don't NEED to follow a track line. I choose to do so because it's far more accurate, useful and reliable than the bit of kit I'm required to install. There is plenty of evidence to suggest that leeches work in a number of medical treatments but I would rather my doctor prescribed some pills that we know do work, quickly.

I've flown a reasonable number of 'experimental' aircraft in both the USA and Australia, none of which had a backup 'wet' compass. I never got lost and, amazingly, neither do any of the other pilots that fly with the (lack of) same equipment. Obviously the FAA/CASA and EAA (US & Oz) don't know what they're talking about.

As I say, if you want one because you enjoy the challenge of navigating like Amelia or because you have a vintage aircraft and it would spoil the aesthetics (I'd be the same) then fill your boots. But for others who would prefer to use more up-to-date methods of getting from A to B (in a straight line) and don't want to waste panel space and money on a bit of kit that is really destined for the Decca Dustbin I would like to see the LAA rid us of the requirement to fit one.

Must dash and polish the mirrors. It looks like the sun may break through and I'll be able to get the midday 'shot'. These new, fangled, sextants are great but I think I'm still required to carry a longstaff because that's what the Vikings did.
Paul Simmonds-Short
042301

mikeblyth
Posts: 155
Joined: Tue Mar 18, 2008 8:24 am
Location: Bedford UK

Re: Compass erroprs

Post by mikeblyth » Sun Feb 18, 2018 9:40 am

Agree Paul and would like to add that display is very clear and easy to follow with a digital
read out. :D
Mike Blyth
005633

User avatar
Flying John
Posts: 108
Joined: Mon May 30, 2011 6:40 pm
Location: Farthing Corner and Rochester
Contact:

Re: Compass erroprs

Post by Flying John » Sun Feb 18, 2018 8:01 pm

If you have magnetic heading from your compass and your track over the ground from your EFIS then you can calculate wind direction and then if you have Pitot derived speed and GPS speed you can get the wind direction too.

Some EFIS with magnetometers do this calculation for you and if you have one so equipped, I too cannot see the need for Nelsons equipment - HOWEVER, when it all goes quiet on the electricity front you can keep the aircraft level, by looking at the bubble :lol: :lol: :lol: :lol:
John Luck
028282

PaulSS
Posts: 43
Joined: Wed Mar 15, 2017 6:04 am

Re: Compass erroprs

Post by PaulSS » Mon Feb 19, 2018 2:20 am

Haha, I wonder how those with a vertical mount compass and no bubble manage when the electricity stops :D

Yes, just chuck a magnetometer into the EFIS circuit and it'll calculate the wind for you. Or, as you've suggested, we can work it out using a whizz wheel (given track, heading, TAS and GS). But why on earth would you ever want to do that :shock:

Not aimed at you, John: Up in the ether we only want to know what the wind is doing so we can work out a heading (to achieve a track) and GS. As I said before, if that's what you want to do then please crack on and enjoy the whizz wheel wonders or the 1:60 calculations (yes, I can). But I think, with all the wonders of modern technology, that is just the tail wagging the dog. Why do I need to do that when I've got a lovely track line and ground speed presented to me courtesy of electro gizmos in space. Maybe I'd like the wind information for landing, well look out of the window at the windsock, smoke, crops blowing etc etc, instead of relying on a calculation. Yes, we can work out the wind but do we really need to and why mandate the fitment of gear if that's its only purpose in the modern day.

Oh, but what if both the generators on the 912iS fail AND your iPad (that was just 5 seconds ago fully charged as a result of being plugged into the aircraft) suddenly runs out of juice AND the iPhone in your pocket also stops working AND you now have no idea where you are, even though you did 10 seconds ago? THAT'S when you'll regret not having a whisky compass!! Binomial probability was never really my thing but I think it's gusting nigh on impossible.

There are plenty of other authorities who have seen this mandatory equipment of a compass as pointless, especially given the inaccuracy and dubious usefulness of them and I reckon it's time the LAA did the same.

(All corresponded without the aid of a quill and using a modern device that has never failed but has its smaller brother alongside, just in case I DESPERATELY need to send an unnecessary message. Talking of which, I must go and check the aircraft flag locker in case of a radio failure)
Paul Simmonds-Short
042301

mikeblyth
Posts: 155
Joined: Tue Mar 18, 2008 8:24 am
Location: Bedford UK

Re: Compass erroprs

Post by mikeblyth » Mon Feb 19, 2018 9:15 am

Would be nice to have a quill, tablet and chisel getting worn :lol:
Mike Blyth
005633

Clive Richards
Posts: 22
Joined: Thu Jul 09, 2009 11:12 am

Re: Compass erroprs

Post by Clive Richards » Mon Feb 19, 2018 8:09 pm

I question what are you going to use for direction if the gps signals are jammed most of the eletronic gizmos do not have magnetometers fitted compass may be useful then
Clive
035718

PaulSS
Posts: 43
Joined: Wed Mar 15, 2017 6:04 am

Re: Compass erroprs

Post by PaulSS » Tue Feb 20, 2018 2:52 am

(a)When has that ever happened (and I'll tell you the answer if you like)? If the GPS constellation is being jammed then we've got bigger problems to worry about than a poxy wet compass and I'll probably be in a bomb shelter instead of puttering around in a homebuilt.

(b)I think I did mention a magnetometer and that gives me a compass but let's assume I've lost both generators, load shed the EFIS and Kim is jamming the GPS constellation :shock:

(b)Should I have no GPS information then the same two devices that I previously spoke of, iPad on the panel and iPhone in my pocket have their own in-built and independent compasses. No, they have not been swung to within 0.00026 degrees but they're more than enough to get any competent aviator pointing the right way.

(As a trivial sidenote, I do wonder why we swing the compass with all electro gubbins on, when the only time I would ever look at it would be if I'd lost all my electricity)

My calculator doesn't have enough numbers to calculate the probability of Kim + double generator failure + 1 fully charged iPad + iPhone from my pocket + not knowing where I am when I did 10 seconds ago + all this being solved by a dubious bit of kit that bounces all over the place, can barely be read to within 5 degrees and likes to wander all over the place if I dare to accelerate etc.
Paul Simmonds-Short
042301

Brian Hope
Posts: 1271
Joined: Tue Jan 08, 2008 8:28 pm
Location: Sheerness Kent

Re: Compass erroprs

Post by Brian Hope » Fri Feb 23, 2018 8:34 am

What navigational equipment is mandated in a light aircraft? Sure, most LAA members have tablets. phones and various forms of GPS and/or EFIS, but that is personal choice and (usually) in their own aircraft. Something has to be mandated though, or you could end up with an aeroplane with no navigational kit in it at all. Better a compass perhaps than every aircraft owner being told they have to fit an approved GPS costing hundreds, or even thousands of pounds.
014011

PaulSS
Posts: 43
Joined: Wed Mar 15, 2017 6:04 am

Re: Compass erroprs

Post by PaulSS » Sat Feb 24, 2018 12:12 am

Surely having either is okay.

If you don't want to have a GPS, EFIS, tablet, smart phone etc then don't; have a compass instead and enjoy the wonders of navigating with it. If you do have any/all of the above, there is no need for a compass. If they manage to navigate in Australia and the USA with ONLY a GPS etc then I reckon it is possible in the UK.
Paul Simmonds-Short
042301

Clive Richards
Posts: 22
Joined: Thu Jul 09, 2009 11:12 am

Re: Compass erroprs

Post by Clive Richards » Sat Feb 24, 2018 11:49 am

Well I for one will keep the compass have the army stopped having exercises now ?
A few years back notam for gps jamming Brecon range over welsh mountains near Barmouth with 2 gps aboard both decided were in different places noticed because the heading on. DI & compass still agreed but bearing and distance to run on gps did not.
Have checked and my new Android phone has magnetometer but selecting a compass app and trying it, it' is not stable having a magnet on protective case dose not help.
Have you checker you have a reliable magnetometer derived heading not just a gps derived one, with a compass you know this is magnetic heading unless you place something near it to affect it I check compass and gps with runway heading when lining up.
Clive
035718

User avatar
jangiolini
Posts: 110
Joined: Thu Jan 03, 2008 4:14 pm

Re: Compass erroprs

Post by jangiolini » Sat Feb 24, 2018 6:43 pm

We regularly have GPS jamming going on on the West coast of Scotland when Operation Joint Warrior was taking place it even wiped out our Tetra radio system mobile phones and goodness knows what else so relying solely on GPS is stupid dangerous and not good airmanship... At least a compass will if its properly installed looked after and no one puts metallic objects in its way will give you half an idea where your going as will practicing map and compass navigation with gross error checks. We are becoming too machine orientated Keep it simple and keep the skills up.
John (AKA Luddite and a proud member of the flat earth society :twisted: )
John Angiolini
036444

User avatar
jangiolini
Posts: 110
Joined: Thu Jan 03, 2008 4:14 pm

Re: Compass erroprs

Post by jangiolini » Tue Feb 27, 2018 11:42 am

I reread your post Paul, and shake my head with disbelief that someone with your obvious experience would ridicule instruments that might just save your life if you were stupid enough to run out of power as happened to an experienced Kingair crew in OO-LET result crash. Also G-PCOP also Kingair talked down by RAF due to pilots not switching on generators, glass cockpit failed when battery ran out but their wet compass continued to work fortunately. Need I go on experimental/home builds maybe agricultural but we generally get there and do ok with steam powered instruments.
John
John Angiolini
036444

User avatar
mikehallam
Posts: 576
Joined: Sun Jan 06, 2008 3:12 pm
Location: West Sussex
Contact:

Re: Compass erroprs

Post by mikehallam » Tue Feb 27, 2018 1:30 pm

Hi John,

Don't fret, they're just winding you up - as with nothing better to do during this hardly flyable wx, some mischievous folk have taken to mild trolling !

I agree that it's absolute nonsense to even discuss saving a minute amount of space and mass by deleting/ignoring the compass.

Impressionable folk might actually begin to believe in ditching this essential back up.

[I guess if electrical loss &/or gross interference happens, one's ears could tell something from engine note: eyes looking out if you're above the hills and at too low low a/speed it all goes floppy ! - But at least with a paper chart & compass you have a Nav. chance VFR]

mike hallam.

Post Reply