OPNLguy From , joined Dec 1969, posts, RR: Reply 1, posted (9 years 6 months 4 weeks 12 hours ago) and read 1875 times:
Nav data updates don't usually follow calendar month and instead usually follow 14-day or 28-day cycles, with ATC commonly using 28-day or 56-day cycles. The effective time (here in the US, anyways), is 0900z or 1000z, or about 3:00 am. depending upon the time of year. Very few flights flying at that time, so any changes between datasets will affect the fewest number of aircraft. The effective time may be different elsewhere, but the MX folks change out nav data cards on overnight MX... Simply stated....
Dc10hound From United States of America, joined Dec 2000, 463 posts, RR: 7 Reply 2, posted (9 years 6 months 4 weeks 11 hours ago) and read 1852 times:
The FMS on a B757 will not let you load a new nav data base unless the aircraft is in the "ground" mode. this is done to prevent corruption of the data base inflight - not a good thing.
"Eagles soar. But weasels never get sucked into jet intakes.."
Jetguy From , joined Dec 1969, posts, RR: Reply 3, posted (9 years 6 months 4 weeks 8 hours ago) and read 1811 times:
Lest any of you get the idea that what George and Mark said was the way all aircraft FMS's handle the situation...
The Universal UNS1-C boxes that are faily common on bizjets have four internal databases, two of which are available to store Jeppessen supplied navigation data. (The other two are for pilot supplied navigation data and flight plan route storage.) The nav data databases are labeled "Active" and "Inactive"
To answer Henry's question, the database updates are published several days prior to their effective dates. On our equipment we simply load the new information (supplied to us on a Zip disk) into the inactive database and at the appropriate date and time it automatically switches to the active database without any further input from the crew. The "dual database" system also allows us to load two current databases, for example and expanded U.S. and European database along with and expanded Pacific Rim database. Using multiple "expanded" databases is helpful when we're flying to some of the smaller international airports - the expanded regional databases have more approaches and nav data than the larger worldwide databases do.
Cx flyboy From Hong Kong, joined Dec 1999, 6129 posts, RR: 57 Reply 4, posted (9 years 6 months 4 weeks 5 hours ago) and read 1789 times:
We only look at the nav data validity when we are on the ground during preflight. If it is valid for that moment, it is fine. If it became out of date prior to your setup, then we update it. This is done by simply selecting the next period of validity on the FMC CDU and placing it over the current one. The aircraft nav data is now updated.
If it looks like it will become invalid sometime after airborne, we still don't change it. It is inhibited in the air. We simply fly using the previously loaded data, and allow th next crew to update it.
Md11nut From , joined Dec 1969, posts, RR: Reply 5, posted (9 years 6 months 3 weeks 6 days 18 hours ago) and read 1707 times:
As Jet Guy mentions for Universal FMS, other FMS are similar. It has two navigation databases. One is selected active and the other contains the "future" database. Maintenance people usually get the nav database ahead of the effective date (for example for database that is valid from Nov 1 to Nov 29, they would get it on October 15). This enables the maintenance personnel to load the next database ahead of time. For pilots, it is a simple process to select the "inactive" database (that has the new date). Some FMS does this automatically since it knows the time and date.
Jetguy From , joined Dec 1969, posts, RR: Reply 7, posted (9 years 6 months 3 weeks 6 days 9 hours ago) and read 1652 times:
I can't answer for "all" airline equipment, but most of the many different systems will handle the scenario in either the way that I described, or in the way that is mentioned in the other posts. The Universal FMS would let you load data in flight either, but it does allow you to swap previously loaded databases.
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