The 767 is essentially the same as the 757. The newer aircraft from the factory are equiped with 3 IRS 2 GPS for updates & VOR DME same as the 757. The older aircraft had only the 3 IRS units and VOR DME updating.
The L1011s that ATA flies either have dual GPS or triple INS. There are no VORs in the middle of the ocean, but the INS units use VOR signals when available to update their position. I was fortunate that the VLF Omega units were replaced with GPS before I got on the airplane.
The 737's we use has two dual IRS's , laser gyro's, updated by dual GPS, VOR/DME. They can go 2.0 hours without anyupdating with zero drift, they can go 6.0 and remain within the required RNP without any updating. Pretty amazing stuff.
The 727 has two Universal GPS unity which seem to do a pretty good job.
On the B-707 I used to fly when I as stationed in Germany, we used two INS's (Inertial Navigation Systems) with a handheld GPS backup for the tie-breaker vote. I think the rules are a little more strict now, but we never got lost.
Now, we have two GINS (GPS-aided Inertial Navigation Systems) and a navigator. Regardless, I always take my handheld Garmin GPS as a last resort. Take care.
Not sure what you are looking for. ETOPS is mainly a planning exercise. Maybe look at the MEL to see what could prevent a dispatch under ETOPS. When airborne, just keep a close eye on the WX at the selected airports, if WX goes below minima before you enter the ETOPS zone, then do not enter. Just try to find a new suitable airport and amend routing. If it goes below when you are already in the zone, then just continue as normal.
We crossed the Atlantic in the 60's using DR, Cel Nav and Loran "A" (WWII stuff), routinely came within 10-15 miles of our entry points. At 360 KTs thats is only 2-3 minutes off course. The only time we every got in troulbe is when the navigator tried to use our new INS-42, it was a stand alone unit, one of the first intertials made by the Singer Sewing Machine company. Boy we really got lost.
Finished my ETOPS check. I guess our fleet manager wants all circles drawn with a quarter then the info inside the quarters on the plot chart. Other than trying to get a quarter through security it was no big deal. I will hopefully go the Vietnam next month, that would be a nice start.
ATC pretty good, WX this time of the year shouldn't be a problem, watch out for the the low transition level (FL60, I think). Saigon: Landing 25R(ILS), or 07L (VOR/DME), expect T3 ARR and T3 DEP from/to the east. Unless you are going on vacation, then forget the whole thing....