IRS Initial Position
Joined: Aug 2013
Posts: 351
Likes: 23
From: South Alabama
Litton 51's
In the days of the Litton 51's we always updated along the way over a known point. The INS would remember that posistion unless you updated again, or deleted it.
If you didn't update, you could be a bit off after a 10-12 hour flight.....
The last airplane I flew had triple laserefs with dme/gps updating.
The system always remembered the last update position.
If you didn't update, you could be a bit off after a 10-12 hour flight.....
The last airplane I flew had triple laserefs with dme/gps updating.
The system always remembered the last update position.
Joined: Mar 2006
Posts: 13
Likes: 0
From: Ormond Beach
Originally Posted by JammedStab
One can go back to basics. Pull out your Jepp chart that shows the ramp area and measure off the lat/long coordinates(maybe compare them with the aerodrome reference point to make sure they make sense) and then input those coordinates.
Joined: Feb 2003
Posts: 1,078
Likes: 46
From: Brighton
For example here in the UK they're talking about switching off lighthouses, because everyone uses GPS now.
Joined: Oct 2003
Posts: 662
Likes: 5
From: If this is Tuesday, it must be?
Orfordness lighthouse, a major one for 300+ years, was decommissioned a few weeks ago.
Joined: May 2000
Posts: 3,204
Likes: 2
From: Seattle
You can get fine enough coordinates (within 0.1 NM) from the 10-9 page if there are not any discrete gate coordinates.
Today's Laser Ring Gyro IRUs are pretty accurate, even without updating. Old IRUs with mechanical gyros were much more sensitive to initial position accuracy. Also, the software that integrated them into the nav system was a key factor in how well they would take and hold an update. Still, it was possible to get good accuracy after starting from a moving aircraft carrier, as long as the IP was within 1/2 mile or so and the initial ship's velocity was accurately input...
Today's Laser Ring Gyro IRUs are pretty accurate, even without updating. Old IRUs with mechanical gyros were much more sensitive to initial position accuracy. Also, the software that integrated them into the nav system was a key factor in how well they would take and hold an update. Still, it was possible to get good accuracy after starting from a moving aircraft carrier, as long as the IP was within 1/2 mile or so and the initial ship's velocity was accurately input...
Joined: Dec 2012
Posts: 1
Likes: 0
From: Saint Petersburg
Guys, today was flight from Budapest, gate 34. I entered GPS position in FMC and compared it with gate coordinates at the placard over the gate number. I was confused! GPS shows coordinates N47.25,9 But placard says, that gate coordinates N46.25,9. One degree latitude difference!!! I cheked it in jeppesen chart - N47.25,9. So, that's why i always use GPS position or ARP from database in FMC.
Joined: Mar 2006
Posts: 13
Likes: 0
From: Ormond Beach
Originally Posted by shturman
Guys, today was flight from Budapest, gate 34. I entered GPS position in FMC and compared it with gate coordinates at the placard over the gate number. I was confused! GPS shows coordinates N47.25,9 But placard says, that gate coordinates N46.25,9. One degree latitude difference!!! I cheked it in jeppesen chart - N47.25,9. So, that's why i always use GPS position or ARP from database in FMC.
Joined: May 2010
Posts: 645
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From: europe
As someone who has flown the Atlantic in pre GPS days, and who regularly managed to make my coasting fix (NDB or VOR) without any undue concerns, what precisely is the problem you are alluding to?
Might I suggest that if your GPS or IRS is not functioning as perhaps it should in this modern day and age, that you switch it off and go back to basics....assuming that they teach these nowadays.
I still fly all of the ponds, but still use basics as a back up to the modern stuff. Given the excellent wind/temp reporting that they now have, I manage to get within plus or minus 40 miles of the GPS displayed position. Never quite sure though whether it is me or him which has miscalculated!
Whichever way you look at it, and assuming that all is done correctly, eventually you will start to hear VHF voices on the frequencies and in the languages that you hoped for!
Might I suggest that if your GPS or IRS is not functioning as perhaps it should in this modern day and age, that you switch it off and go back to basics....assuming that they teach these nowadays.
I still fly all of the ponds, but still use basics as a back up to the modern stuff. Given the excellent wind/temp reporting that they now have, I manage to get within plus or minus 40 miles of the GPS displayed position. Never quite sure though whether it is me or him which has miscalculated!
Whichever way you look at it, and assuming that all is done correctly, eventually you will start to hear VHF voices on the frequencies and in the languages that you hoped for!
Joined: Mar 2006
Posts: 13
Likes: 0
From: Ormond Beach
Originally Posted by deefer dog
As someone who has flown the Atlantic in pre GPS days, and who regularly managed to make my coasting fix (NDB or VOR) without any undue concerns, what precisely is the problem you are alluding to?
Much hilarity ensued.
Joined: May 2001
Posts: 809
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From: A few degrees South
All those airport refs, gate positions, take off resets were useful before GPS was integrated.
Now just use one of the approx points, and the GPS will correct it for you. Within limits, of course.
Or do like most people do: use the GPS coordinates in the first place.
Now just use one of the approx points, and the GPS will correct it for you. Within limits, of course.
Or do like most people do: use the GPS coordinates in the first place.
Joined: Mar 2006
Posts: 13
Likes: 0
From: Ormond Beach
Originally Posted by latetonite
All those airport refs, gate positions, take off resets were useful before GPS was integrated.
Now just use one of the approx points, and the GPS will correct it for you. Within limits, of course.
Or do like most people do: use the GPS coordinates in the first place.
Now just use one of the approx points, and the GPS will correct it for you. Within limits, of course.
Or do like most people do: use the GPS coordinates in the first place.
Joined: Oct 2013
Posts: 23
Likes: 0
From: Out of radar space
ARP reference
Gate coordinates in the FMC, ARP coordinates in the FMC?
Why would the FMC need either one of these?
Why would the FMC need either one of these?
