Over the years, the air force has used versions of transports including the Douglas DC-3, Israel Aerospace Industries Arava and Boeing 707 for missions such as airborne early warning and electronic intelligence-gathering. But faced with more sophisticated threats, the service several years ago decided to upgrade its capabilities.
It wanted something smaller and cheaper, but with much more capability than legacy systems. With the understanding that some equipment cannot be purchased on the open market, Israel's own advanced technology and determined people were called upon to deliver a cutting-edge surveillance capability.
Air force commanders held a series of long meetings with engineers from IAI, before hearing the phrase that they had waited for: "This can be done." The result was a programme to develop two special-mission variants from the G550: a business jet designed for people that have money but not time.
A visit in the passenger cabin of such an aircraft leaves a smell of fine leather in the nose and an impression of super luxury, but it was the model's other advantages of long range and high speed that formed the basis for its selection for military use.
The G550's transformation into an air force asset was not a simple task, but today Israel is operating the type in two adapted versions: the "Eitam" AEW aircraft and the "Shavit" ELINT platform. Both are equipped with technologies developed and manufactured by IAI's radar and electronic warfare subsidiary Elta Systems.
For the AEW mission, the Eitam carries the company's EL/W-2085 multi-sensor suite, which comprises four conformal L- and S-band radars, plus communication and electronic support measures, communications intelligence and ELINT capabilities and identification friend-or-foe equipment, plus various other antennas mounted on the fuselage.
Surveillance data gathered by these on-board sensors is fused and continuously cross-correlated, enabling the suite to be automatically cued to search for specific targets, up to full 360° coverage.
The AEW radar uses four main active electronically scanned array antennas for wide-area coverage and to allow an instantaneous focus to be made on selected targets of interest. Elta says the radar can be pointed at any direction at any time, with the parameters of its arrays controlled by computer. As a result, surveillance can be limited to a battle zone and other areas of interest using a much higher scan rate.
A special mode for manoeuvring and high-value targets also employs a high scan rate, with beam shapes optimised to ensure tracking performance and extended detection range. Verification beams are sent towards specific, individual and newly detected targets, eliminating false alarms, says Elta. Track initiation is achieved in 2-4s.
Visiting such a highly classified air force squadron creates a big problem for a journalist, as it is obvious that it has already been involved in all sorts of operations that will stay under security wraps for years to come.
Questions about the Nachshon unit's operations to date were met with a polite smile, but its commander, a Lt Col, eventually commented: "We can operate at any range needed to defend the security of Israel."
The data sheet for the G550 lists the business jet as having a range of 12,500km (6,750nm) and an endurance of 11h, and IAI has previously said that the Eitam can fly for over 9h above 41,000ft (12,500m).
Asked whether the squadron has performed missions across such an envelope, the commander's smile appeared again, but no details followed.
The international media has claimed that Israel launched air strikes last year to destroy a secret nuclear reactor in Syria and convoys carrying arms in Sudan before they reached Hamas militants in the Gaza strip. Asked whether his unit was involved, not even the smile remained.
Climbing aboard one of the air force's G550s inside a brand new hangar at Nevatim delivers a sharp contrast to memories of business jets and champagne. Now equipped with its radar equipment and conformal antennas on each side of its fuselage, the modified Eitam is a windowless aircraft.
Asked whether a sense of claustrophobia or suffocation can be felt during long missions, Maj G - one of the aircraft's on-board mission commanders - says it was considered a potential problem before the aircraft entered operational use. But the need to fully concentrate on the images being shown on the mission system's large screens very quickly becomes the only dominant sensation, he says.
Squadron personnel worked very closely with Elta's engineers and technicians to design a system that would provide the best performance, and the aircraft's six air controllers sit in the aft section, behind a small galley in the centre of the cabin.
And while all signs of the luxury normally associated with the civil G550 have been eliminated, one special comfort has been provided. The controllers' seats have been covered with a special fabric, which gives them "a more fresh and easy felling", another squadron officer says.
Although the AEW aircraft attracts the highest profile attention, the air force's ELINT-configured Shavit also delivers outstanding capabilities. Going inside the aircraft, which has also been packed with sensors, was not allowed, but sources say the new asset has "completely changed the way in which Israel is able to build the threat picture from far away".
Details about the performance of Israel's new Shavit Elint aircraft remain highly classified. ©Israel Aerospace Industries
In common with the Eitam, the ELINT aircraft carries a comprehensive self-protection system that is operated according to the known threats that it may encounter on operations. "We are very well protected," the squadron commander notes.
Now fully operational, the air force's Nachshon squadron is delivering strategic capabilities that in the past were only on Israel's wishlist. IAI has already delivered its first AEW-configured G550 to launch export customer Singapore, and views India as another near-term sales opportunity for the type.