Why India refused to buy the MiG 31
The Indian Air force used the MiG 25 long Range Interceptor/Reconnaissance planes to gather intelligence and take photographs of enemy installations, flying very high and speed MiG 25 has no other competitor in South Asia, During the Kargil war IAF used the MiG 25 to gather intelligence over Pakistani soil and Take as many as photos about their Strategic Locations, while PAF has no Aircraft who can match the speed and Altitude of Mig 25,
After 2006, with the arrival of remote sensing satellites and synthetic aperture Radar, IAF decommissions all the MiG 25, that time IAF had Seven MiG 25, while one was crashed, After the retirement, The Russians offered more advanced long range Interceptor MiG 31 along with ultra long range missiles, The Indian Government also accepts the Russians offer and asked the IAF to check the deal, But IAF eventually rejected the deal, and moved with repeated number of Su 30 MKI orders,
The IAF, takes a good decision, same like all other times, because of the usage and current scenario MiG 31 is not required, since rival forces have good fighters and missiles to counter the MiG 31, The MIG 31 is absolutely a good platform, no question, However it's just a Interceptor, While most of the Pakistani and Chinese Fighters can be countered very easily by the Sukohi's and ground based missile systems, the Pakistani F 16 Block 52 armed with AIM 120 AMRAAM can easily chase the MiG 31 and it down, the same goes for China with Su 30 MK with R 77 missiles can easily kills the MiG 31, unlike Russia, They need to engage large number of NATO planes and High flying Reconnaissance drones, with the long range Air to Air missiles, and High altitude of flight, The MiG 35 can easily shoot down almost all kind of recon drones and other recon platforms like AEWCS and U 2 Spy plane.
The Interesting matter is because of the R 33 Long range radar guided missile, The MiG 31 can able to destroy any long range US made Bombers, While US has comes with large number of Bomber fleet, The Russians found a Long range Radar guided missile to counter them, The High power Zalson Phased Array Radar in the MiG 31 can easily tracks and guide missiles over 300 kilometers, they demonstrated the capabilities by destroying a cruise missile using the R 33 Zalson combo, the same can be used for destroying enemy satellites too,
But so far the ASAT capabilities not been tested, But it's clear during warfare the Russians could use the R 33 missiles to kill the satellites, However it's hard to identify the Enemy satellites in the space, by using the Zalson, those satellites also travel much higher speed, making difficult to track and lock, however the R 33 can reach the 300 Kilometers in just 150 second, The average speed of more than 4.5 mach,
In terms of India, The MiG 31 can be used against the Chinese H 6 bomber fleet and long range cargo planes, But the same can be done by using the Su 30 MKI with R 77 combo, the R 77 missile can strike targets far 100 kilometers, however the MiG 31 with R 33 combo is best compared to Su 30 in terms of Interception, but the IAF need the Su 30 as a Swing role, like multiple Air superiority missions.
However the main aspect is Currently most Air forces has good electronic attack capability, that can easily spoof radar guided missiles, the same will increases when it comes to long range, because of long range the missiles data link can be easily interrupted by the Fighters Defensive systems, Even those American bombers are equipped by larger sensors and defensive systems, meanwhile the same not applied to the Chinese H 6 bombers, Chinese are new to electronic attack,
The MiG 31's relies on it's flying speed and Altitude, to evade from enemy missiles and Anti aircraft missiles, But currently most of the fighters comes with high speed Missiles to engage threats at much higher altitude and speed,
Also during the Indian terms the MiG 25 suffered lack of spare parts, makes only less number of Planes makes airborne, even at the same time Soviet and Russian Forces used more than thousands of such planes in its inventory,
However IAF takes a good decision by ordering more number of Su 30 MKI to sticks with single platform, if they selects the MiG 31, they have to make another ground for newer platform, even now IAF struggling with many models of Fighters because of logistics and spare parts issue.