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-   -   AAIB Comment in Clued Up (https://www.pprune.org/private-flying/489266-aaib-comment-clued-up.html)

peterh337 30th June 2012 20:40


Or do you imply a database one paid for is more reliable because of the amount one paid for it?
In terms of risk management / quality control, yes, obviously, exactly that.

hoodie 30th June 2012 22:20


Originally Posted by peterh337
That would be quite clever since the UAV would be using military encrypted GPS signals... not the civilian signals.

Is there such a thing as 'military GPS signals'? I had understood that civilian and military GPS was the same ever since the DoD switched off Selective Availability in 2000.

mad_jock 30th June 2012 22:27

There is still a mil frequency which they use in conjunction with the civi one.

The civilain freq used to have a fudge factor built into it which knocked the timing off so it wasn't as accruate as the mil one. They can also switch it off if they so desire and leave the mil one on.

flybymike 30th June 2012 22:28


And how would you think the waypoints are defined in the database? Lat/long numbers, any chance? Or do you imply a database one paid for is more reliable because of the amount one paid for it? I'am afraid I am missing something somewhere.
Entering waypoints on a moving map GPS is a simple matter of clicking the mouse or pressing the screen at the appropriate point. The way point must then be in the correct place on the route and map. If in doubt do a "simulated" flight of the route. Entering multiple digits and setting off blind and hoping for the best is simply asking for trouble. Reminds me of one time I entered "Bangor" into a route simply using a stored database of towns in the GPS. This was on a flight to Caernarfon in North Wales. I spotted that something might be wrong when it tried sending me off across the Irish Sea to Bangor in Northern Ireland. Someone later remarked that I was lucky not to have ended up in Bangor Maine in Canada (or wherever it is.)
If you can see the route on a map before you set off you can't
really go wrong.

goldeneaglepilot 1st July 2012 00:12

MJ

Ten years ago you would have been right - now (roughly)three modes L, P or M, the L is roughly the old military standard of ten years ago, typical accuracy with 6 sats is about +/- 300mm (dependent on RX)

P is an encrypted signal version of L and more resiliant to blocking

M is much more complicated and from 2013 will become even better due to the deployment of beamed signals to a specific area.

L is what civilian aircraft use.

peterh337 1st July 2012 07:37

What is L2?

goldeneaglepilot 1st July 2012 07:46

L2 - a second frequency that can either be used alone (L2C) or in conjunction with the L1 frequency (often refered to as the coarse date frequency) to improve the overall accuracy of "L" for civilian use, which places the equipment outside the Wassenhar agreement for dual use technology

mad_jock 1st July 2012 07:50

The mil encypted was always on a seperate frequency.

They did actually use the civi one as well to be able to adjust out atmospheric effects.


Mind you my knowledge is from being constripted due to knowledge of newtons laws and pocessing a scientific calculator on a gun position to the command post when the lay computer went tits up.

SMIG Badger Finnch and BSM Murphy I think there names were, after the intial "I don't care if your a sapper son" followed by a belt round the head with an A4 binder gave me a crash course in position fixing, firing out the errors, cresting and other such gun bunny perversions. Easy week with a rover full of survey gear out the window. Swapped for "confirm" "confirm" "down safety" "No 1 gun, 5 rounds fire for effect down safety fire!!" noisy bastards.

topoverhaul 1st July 2012 08:06

L2 is 1227.60 MHz as opposed to L1 at 1575.42 MHz. Latest satellites will transmit both frequencies and allow a civil dual frequency receiver to correct for ionospheric delay, the largest source of error, without needing to rely on the WAAS signals.

goldeneaglepilot 1st July 2012 08:19

We are going all techie on here - my crayons are struggling to keep up!!

mad_jock 1st July 2012 08:40

Fair enough.

As I said I was conscripted due breaking the number two rule of letting on that you know something. They had been given doppler velocity measuring things for the guns and a drinking mate was a number one. Him being a gun bunny was thick, so I was explaining how doppler worked and how that if you had the speed you could relatively easily work out the fall of shot. Someone overheard and grassed me up.

goldeneaglepilot 1st July 2012 08:46

Did the conversation go something along the lines of "you horrible little man, pin your ears back and remember I am your God and your father - now keep your mouth shut. 50 press ups on the spot!!"?

Gun Bunny's are as bad as Rock Apes, in fact they are just a genetic mutation of each other.

Saying that modern Rock Apes do a fantastic job as QRF

PS: My brother in law was a Rock Ape as part of a QRF - disgusting to go out with them for a drink!!

mad_jock 1st July 2012 09:28

Nah its wasn't to bad, in fact after the second day when some stupid tart managed to burn out the alternator on the coms wagon "the belt was making an awfull noise so I tightened it" and then killed the batteries and I butchered a 4 tonner to get things going again. OC "Young man is that authorised" BSM "yes sir by me" Got one of the plant fitters from the tankies to drop one off and a tool box inside an hour and had it fixed between fire missions. The SMIG stopped the bollocking for getting oil on the mission sheets.

After that I had access to the BSM's private store of Brown Ale, bastard though wouldn't let me have the rugby on the radio though. Missed one of the rare Scottish victorys over England at Twickenham.

I was excempt from that running round the gun bollocks. Did have a shot of being number three though when on the last day the special battery/thing turned up. Which earned me a burnt boot toe cap and another belt round the ear for trying to see how much flame I could get out the back of the gun by releasing the breech at the back of the recoil.

The burning of the charge bags with the BSM was top fun as well.

So in the end a not to bad exercise. The other lads who went to Otterburn came back with trench foot and a sense of humour crisis.

fattony 1st July 2012 12:46


I was conscripted due breaking the number two rule
What was the number one rule?

mad_jock 1st July 2012 13:32

Never volunteer for anything.

This is vitally important when there is "otterburn" being mentioned anywhere in the building. Just typing the word makes me feel cold, wet and pissed off, makes Dartmoor feel tropical.

Molesworth 1 1st July 2012 14:02

I was quite surprised to see this comment in Clued Up as I read the AAIB report every month but I don't remember ever seeing "overuse of GPS" mentioned as a factor in any accident.

172driver 1st July 2012 15:27


"Some of the more common, and preventable, incidents involve poor situational awareness, largely as a result of the overuse of GPS."
At first I thought Sir Niall was confusing the date with April 1st. Had to check my copy of Clued Up first and yes, there it is.

Unbelievable.

I don't think I have ever read anything as idiotic about aviation as this comment.

Poor situational awareness is due to GPS? In which cave and which century do these people live? The REALLY scary thing about this comment is that it comes from someone professionally involved in aviation.

:ugh:

Sir George Cayley 1st July 2012 15:37

Have you noticed how many thread wanderings are started by some of the more senior (ahem) forumites? :hmm:

Pressing GoTo for the OP here's another thing to consider. The FAA's NexGen plan for ATM is predicated on using technology that will dispense with whirly round radar heads.

If I understand things correctly, ADS Broadcast and Contract will be a major navigation platform for which a "GPS" box is required. Squittering out will show your position to ATS and eventually being able to take in other squitters will let you see other participating traffic around you. Although this is aimed primarily at commercial operators (who don't like the equipage costs) the benefit will be there for anyone to take advantage of.

One important driver is the enhanced situational awareness the technology brings - something I would have thought AAIB would know and support.

SGC

Jan Olieslagers 1st July 2012 15:57


Poor situational awareness is due to GPS?
Negative, or, at least, that is not what I read.

mad_jock 1st July 2012 16:11

Guilty as charged.

Maybe they were meaning that it is becoming more common that the go to function is being used more when people are uncertain of position, then that track is not getting cross referenced back to the chart to ensure that your not going to go somewhere that your not meant to. And people arn't ensuring they actually know where they are mid waypoint thus their SA is compromised.

Or maybe folk have there heads in to much trying to work out what the box of tricks is doing when what it is saying doesn't agree with thier mental model of where they should be.

Just a suggestion.

There is a marked difference between a instrument trained pilot and waypoint usage and a VFR pilots use if they haven't been trained for it. There is also a big difference between an airways only Instrument pilot and a bandit country instrument pilot.


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