September 12, 2017:
The Arab coalition that came to the aid of the Yemeni government in March 2015 was the first large scale Gulf Arab aerial campaign carried out using modern aircraft. The coalition had over 200 combat (mostly) and support aircraft, including several dozen helicopters (most of them armed). When the coalition intervened most of the Yemeni Air force had either joined the rebels or was grounded for lack of maintenance or personnel. A lot of the Yemeni military anti-aircraft systems, including radars and some missiles, were operational.
In the first 30 days of the campaign the coalition flew about attack 2,400 sorties and destroyed what was left of the Yemeni Air Force and air defense systems without suffering any losses to enemy action. One coalition aircraft, a Saudi F-15S, went down off the coast due to technical problems. Both crew ejected and were picked up by helicopter.
The coalition thought they got most of the Yemeni ballistic missiles but it was later found that several had survived but none of those fired at targets in Saudi Arabia (where most were aimed) hit anything because the Saudi Patriot anti-missile capability worked. A ballistic missile hit a coalition base in Yemen during September 2015 and in response the UAE brought in a Patriot battery and other anti-aircraft systems which prevented further losses like that.
The initial air campaign also attacked military facilities the rebels had captured or obtained when units joined the rebels. The air campaign has continued, using smart bombs and guided missiles against rebel forces. The rebels often stored heavy weapons, vehicles and supplies in populated areas and the coalition kept attacking and largely ignored the civilian losses. While this was considered acceptable by most Middle Eastern nations Iran, which now openly backed the Shia rebels, made the most of it in the Western media and the UN.
Iran was less eager to publicize the fact that the Arabs had succeeded in carrying out a sustained air campaign using modern aircraft (mostly F-15s, Tornadoes, Typhoons, F-16s and F-18s) and weapons (GPS and laser guided bombs and missiles) using targeting pods and AWACS aircraft. There were also several Arab operated aerial tankers as well as dozens of helicopter gunships and search and rescue helicopters. All this stuff performed well with Arab crews and under the supervision of Arab commanders.
Iran had long derided (openly and among themselves) the inability of the Arabs to effectively operate these modern weapons on a large scale. That was obviously not true. Nor were the stories the Iranians spread (mostly inside Iran) that the Arabs were using mercenary Western pilots. That proved to be untrue because crew killed when aircraft (18 so far) were lost were named, hailed as heroes and their careers were described in detail. Most of the aircraft lost were Saudi (11) followed by the UAE (4) with Morocco, Jordan, Bahrain losing one each. That was roughly in proportion to how many aircraft each coalition member contributed. Thus the aircraft lost were two F-15s, three F-16s, one Mirage 2000, five AH-64s and four other helicopters plus at least five large UAVs.
After the Saudis the UAE was the largest contributor of aircraft. The UAE sent in about 40 F-16Es (mostly) plus some Mirage 2000s and one aerial refueling aircraft. UAE later sent in more AH-64s and light attack aircraft (armed with Hellfire missiles). The UAE also set up an air base across the Gulf of Aden in Eritrea with at least five Mirage 2000s, three AT-802 light attack aircraft, UH-60 and CH-47 helicopters and several Chinese made CH-4 UAVs (similar to the American Predator). This was mainly to tighten the naval blockade that Iran was sometimes evading to get weapons to the Shia rebels.
Other members of the coalition provided 15 F-18Cs (from Kuwait), ten Mirage 2000s (Qatar), 33 F-16s from Bahrain, Egypt, Jordan and Morocco plus three Su-24Ms from Sudan. Saudi Arabia supplied most of the AWACS and aerial tankers as well as military transports (fixed wing and helicopter). The coalition did use a lot of foreign contractors on the ground for maintenance and tech support, but they have always done that. What scared the Iranians was the skill levels of the Arab aircrew. These pilots had little or no combat experience but since mid-2014 many of them had been flying combat missions against ISIL (Islamic State in Iraq and the Levant) in Iraq and Syria and the air campaign in Yemen demonstrated these pilots, and their ground support facilities, could handle a “surge” (several sorties a day for weeks) and then thousands of more sorties over more than a year of operations.
Iran has not said anything about how they might have changed their war plans now that they know how capable their Arab adversaries are.