The last position at shutdown should not be used as the aircraft may have been moved to another position on the airport .

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 they want me to work that hard, they'll need to pay me more.

Interesting conversation to say the least.

I can see why so many pilots complain about RNAV DEP procedures, you cant figure out how to tell the FMS if the ac is at the gate or at the end of the runway.

Already started. Orfordness lighthouse, a major one for 300+ years, was decommissioned a few weeks ago.

Although the primary reason for that was land erosion, meaning that it's fairly imminently not going to be there. Not directly related to gps at all.

Just pointing it out to someone wondering aloud how to find out coordinates of their location.

Some airports have Jepp pages with gate coords. No need to measure.

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...

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.

I'm not surprised, God only knows who made those placards.

Hope you informed the aerodrome operator rather than leave the hazard there to trap a fellow aviator!

Gate coordinates in the FMC, ARP coordinates in the FMC?

Why would the FMC need either one of these?

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!

Probably the cheeepest bidder from the land of almost right. :oh:

There is no problem. This thread was started by a Serious Aviation Enthusiast, who just got done reading a Serious Aviation Book, wherein was detailed a Mysterious Aviation Procedure in the absence whereof said Serious Aviation Enthusiast became concerned for his life and limb.

Much hilarity ensued.

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.

That only applies to people who actually get to do this every day, not to Serious Aviation Enthusiasts reading Serious Aviation Books.

ARP reference
 

That is what GPS is not localizing. An Inertial Reference with an ARP as a last IRS POS might the best for a specific SID at the airport. For pre-GPS days, it would be always the VORs or NDBs nearby, but at that days, most aircraft also did not have a FMS.