The latter raises some very interesting questions about key design trade-offs, as yet not explained by Sukhoi. The existing design configuration suggests that extreme manoeuvrability was rated to be more important than all-aspect stealth was, suggesting in turn that the aircraft was not intended for use as a deep penetrator in the manner of the F-22 and YF-23. Given the low priority given in Western nations to the maintenance of deep overlapping SAM belt air defences, the susceptibility to aft quarter SAM shots inherent in limited all aspect stealth performance may not have been assessed as a risk worth serious investment in defeating

The basic shaping design observed on prototypes of the PAK-FA will deny it the  critical all-aspect stealth performance of the F-22, critical in BVR air combat and deep penetration operations. Despite this, the extreme manoeuvrability/controllability design features of the PAK-FA, which result in extreme plus agility, result in the potential for the PAK-FA to become the most lethal and survivable fighter ever built for air combat engagements.