Initial reactions of F-35 pilots and air force commanders has been positive, especially now that some F-35s have been in combat (over Syria) and gone up against world class (Russian) radar and electronic warfare equipment. What the pilots who have flown the F-35 agree on is that the software and the degree of automation built in is spectacular. The F-35 has a large number of sensors (receivers for electronic signals, six cameras and a very capable radar) and the fusion of all that sensor data and presentation to the pilot based on the current situation is impressive and makes the F-35 much easier to fly, despite all the additional capabilities it has. This was not some miraculous breakthrough but the culmination of decades of adding most of this computer, communications and sensor tech to warplanes.
One of the most useful functions the F-35 has is its ability to collect data on who is within weapons range passively (without emitting any electronic signals, as with radar) and use a “threat library” to quickly (in real time) compare what visual and electronic data its sensors are receiving and compare it to data in the threat library and present the pilot with the most likely match. This is not a new technique and was pioneered by the U.S. Navy for their nuclear submarines, which also sought to remain invisible (stealthy) to the enemy by using passive acoustic sensors and a library of water conditions (which impact how sound travels underwater) and local geography (how far down the seabed is) to compare what the sub is hearing to a “threat library”. The navy spent a lot of time and effort collecting sounds (whales, schools of fish, surface vessels and enemy and friendly submarines). The very sensitive passive (just listen, not transmit) sonar systems, and increasingly powerful computers on the subs enabled them to track ships long distances, in any weather and without letting the subject know it was being tracked. This was because American subs have long had passive sonar system and computers that used libraries of unique sounds made by individual ships. During the Cold War, the library was full of sound signatures for Russian warships and since the Cold War ended it has been updated to contain a lot more Chinese, North Korean and Iranian subs and ships. From the 1980s on, as computers and hard drives became smaller and more capable, these threat libraries became a key technique in submarine warfare. Naval aviators and the U.S. Air Force noted this capability and saw its eventual use in aerial warfare.
By the 1990s it was recognized that another new technology; data fusion, would be a key capability for combat aircraft (as well as ships and ground forces). Put simply, it's all about taking real-time vidcam, radar and other sensor data (sensor fusion) and other information about the battlefield situation (all sorts of databases and reports), and combining it to provide commanders with a better understanding of current operations, preferably in real time if you are a fighter pilot. The F-35 is apparently the best working example of this so far and what is learned from the F-35 software will be the basis for updated software for older aircraft.
But beyond the data fusion (and automatic sharing with other aircraft or systems on the surface) the pilots were impressed about how effective the “pilot assistant” software was. This is another concept that has been around for decades and more frequently installed in new aircraft. These minor advances get reported but never make headlines. But given the F-35s stealth, maneuverability and sensor/data fusion, most pilots quickly become enthusiastic proponents of the aircraft.
Data fusion was pioneered by those developing the threat libraries for American submarines but in the air, there was a lot more data to deal with and the pace of operations was a lot faster. To use this passive sensor/threat library technique in air combat there was a need for speed in processing incoming data and presenting it to the pilot. It had to be nearly instantaneous to be useful and the F-35 was designed around a sensor/threat library system that could actually do that and do it reliably and consistently.
For this data fusion to work in the air the threat libraries have to be updated quickly and the speed of those updates is still a work in progress. Like the navy (which adopted commercial hardware and software for its subs to speed the update and upgrade process) the air force is currently updating the "mission data files" too slowly to prevent an enemy, especially in wartime, from developing and using deception techniques to degrade the accuracy of the current "mission data files". The air force and navy can quickly collect examples of new data for the "mission data files" but that is useless unless the aircraft can get their version of the "mission data files" updated.
One reason for delivering combat ready F-35s to Israel so quickly was because Israel is one of the countries that has pioneered new technology (hardware and software) to address problems like this. Thus Israel is the only foreign user that was given access to so much of the F-35 source code and permission to modify that software to work with new Israeli developed tech to speed up the "mission data files" process. Israel demonstrated the need for this as soon as they received enough F-35s in 2017 to form a combat squadron and put it into airspace where new model Russian warplanes and electronic equipment was being used. While Russia and Israel are on good terms with each other, Russia does sell their new warplanes and tech to whoever can pay that includes China and Iran.
For this reason, when these early positive pilot reactions to the F-35 were dismissed by critics as PR the professionals knew it was anything but positive PR. With the Israelis, it is different because they are most likely to use those new capabilities in combat first and Israeli pilots have a reputation for delivering very blunt assessments (both public and otherwise) of aircraft performance. That bluntness has always been encouraged in Israel. For decades the U.S. has been building new combat aircraft and upgrades based on input from Israeli experience and that input has generally been very useful.
Israel has 50 F-35Is on order with the first 33 F-35Is to arrive by 2021. The option to buy another 17 was exercised at the end of 2016, based on initial experience. The first 15-20 F-35s were delivered as F-35As and Israel converts them to the F-35I standard. All remaining F-35Is will be equipped as F-35Is at the American factory and delivered ready for action.
By April 2017 235 F-35s had been delivered, mostly to the U.S. Air Force and Marine Corps. By mid-2018 over 300 had been delivered. Over 4,000 F-35s are expected to be delivered by the mid-2030s with more than 70 percent going to the United States.
The 31 ton F-35 is armed with an internal 25mm cannon and, before the SDB (Small Diameter Bomb) arrived, four internal air-to-air missiles (or two missiles and two smart bombs) plus four external smart bombs and two missiles. A new bomb rack allows the F-35 to carry eight SDBs internally. All sensors are carried internally and max weapon load is 6.8 tons. The aircraft is very stealthy when just carrying internal weapons.
Potential foes are concerned and are beginning to show it. In April 2017 it was confirmed that Russia had brought in one of its four new A-50U AWACs aircraft, in part to get a better look at the F-35I and test its capabilities. That works both ways. Similar Russian and Chinese fighter designs are behind schedule and none are in service yet.
In April 2017 one of four new Russian A-50U AWACs (Airborne Warning and Control System) aircraft was spotted in Syria. This U version entered service in 2011 but foreign ELINT (electronic intelligence) experts had not yet had a good opportunity to see how effective it was. To do that you have to get your ELINT aircraft close to an A-50U in a combat zone. In this case, the most effective ELINT aircraft turned out to be several American F-22s stealth fighters quietly (and apparently undetected) operating over Syria. Officially the F-22s were there to perform missions where effective stealth was a requirement. That meant reconnaissance missions during periods when the Russians or Syrians were angry at the U.S. Russia had some of its most modern electronic warfare systems operational and vulnerable to close examination by American and Israeli ELINT.
The other American ELINT aircraft was several new F-35Is. These have been seen flying near the Syrian border but no one is sure if an F-35I or two slipped across the border to join the hide and seek action the F-22s had monopolized until recently. The F-22 and F-35 have more than stealth in common. Both have impressive software that automatically operates the many passive (they don’t broadcast and reveal their position) sensors on board both aircraft.
The U.S. Air Force subsequently admitted that the F-22 was, as was always suspected, carrying out ELINT missions (early sales efforts pointed that out). The F-35 uses a similar but different array of sensors and apparently more powerful software to control the collection and analysis of what is out there and do it in real time. The Israelis have installed a lot of their own hardware and software in the F-35I (which is why it isn’t called F-35A) and both Israelis and Americans want to see what the Israeli version of ELINT do, compared to the F-22 and, one suspects, an F-35A pretending to be Israeli for the purpose of playing with the hostile electronics found in Syria.