Airframe age is a very reasonable argument for new planes, its unarguable. But the japanese 767 really are not going to be useful in a conflict in their region. E3 development is basically grinding to a halt, and all efforts are moving to the E7. Japan will have to wait. The E767's are probably still workable in a more secondary role, further away from the action, Japan has a long front, so if US E7 are based in Japan, the 767 are still mildly useful for more low risk and low intensity areas.I can see Japan buying E-7. Its AEW 767s are newer than any E-3s, & the airframes should have more useful life left, but have the same radar, so should be equally affected by radar obsolescence.
There are plenty of near new <100 flight hours G550. Private jets are often bough more as status symbols than high mileage taxis. The G650 isn't widely different and offers benefit of range, volume, etc, these are problems that can easily be solved with money.*Apparently the G550 is no longer being built for commercial users, & I'm not sure if it's still possible to order a new G550 AEW - but I've seen it suggested that IAI/ELTA is offering a G650 AEW, & conversions of used G550s can be done.
These are good platforms, but they are really in a different category to the E7. They can do basic detection and tracking, and even basic command and control. Single plane incursions etc are not an issue.** SAAB has been reported to be offering a Global 6500-based Globaleye, without the Seaspray 7500E radar, but with nose & tail radars to fill the coverage gaps of the standard Erieye system.
Trying to run at battlespace in a peer conflict with dozens of 5th gen platforms on both sides, hundreds of drones and stealth munitions in the air while countering enemy MESA equipped airborne platforms conducting their own EW capabilities on you, while space war is fought above bringing sats down... Its not the right platform.
Germany acquired Global 6500 for its pegasus program for Sigint and peacetime surveillance.. Its more like the MC-55a..
The Global 6000 business jet-based Persistent German Airborne Surveillance System (PEGASUS) has passed its critical design review (CDR), prime contractor Hensoldt...