Navigation using gyros is a lot more accurate than you might suspect, as long as you can check the drift from currents and update the gyros with an occasional celestial navigational fix or known position.
In fact, this system was used up until fairly recently in airliners when they navigated over long stretches of water, and is known as the Inertial Navigation System, it was actually the primary navigation system fitted on the supersonic Concorde airliner.
However, as has been pointed out, it's only as good as the data fed into it, and this could go disastrously wrong if the wrong data is input. Many will remember the shooting down of the Korean Air Boeing 747 in 1983 over the (then) secret base at Sakhalin Island by Soviet Interceptor aircraft. This is thought to have been caused by an incorrectly programmed INS, and was instrumental in the US President at the time (Reagan) insisting that GPS data from satellites be made more freely accessible.
These days, as a back up to GPS, 747's use an updated version of INS - IRS, or the Inertial Reference System, which uses ring laser gyros and mirrors rather than a mechanical set of gyros. It is reckoned that with the IRS system alone, a 747 can fly 7,000 miles with no further data or references, and be well within one mile of it's true position according to the instruments (and that's with having to contend with 200 mph crosswinds up at 40,000 feet and the like).
I personally would like to see the option to do celestial navigation in SH4, as I think it would add an interesting element of realism. Being able to navigate from fixes off radio stations would be cool as well - and historically accurate too - since that's exactly what the Japanese pilots did to home in on Pearl Harbor for their attack.
|