The US Air Force is reportedly working on upgrading its E-3 Sentry early warning and control aircraft (AWACS) to the new E-3G versions, which come with modern computing systems. However, a major disadvantage of the upgrades is that it reportedly leaves the aircraft vulnerable to hacking.

The US Air Force is reportedly operating a fleet of 32 E-3s across the globe. The E-3G upgrades swap the Sentry's outdated computers with a Red Hat Linux-based system for the main flight computer and Windows-based systems for the workstations, according to a report by Motherboard.

However, the new aircraft demonstrated several "deficiencies" upon undergoing testing, including overheating. A report of an assessment into the E-3G's system, which involved analysing how easy it was to hack the E-3G and its ground support system in a simulation, revealed that the upgraded systems "are highly vulnerable to cyber threats and not survivable".

The E-3G's computers are also allegedly designed to streamline air, sea and land tracks into a single sensor display, which is believed to help enhance target identification, reducing the margin of error. The upgraded ground-based workstations help mission-planning and post-mission data analysis.

According to a 2014 spending and acquisitions report, the E-3G upgrades, which reportedly began over a decade ago, cost the US government over $2.6bn by 2016.

However, the upgraded aircraft's vulnerability to hacking led to the Air Force refraining from certifying the E-3G as ready for further operational testing, which in turn has temporarily halted its trials. This means that most of the Air Force's E-3 crew may have to continue relying on technology from the 1970s and 1980s, which was around when the E-3 Sentry was first deployed.