This work presents a performance analysis on unmanned aerial vehicles (UAVs) assisted wireless

communications systems, where one of the UAVs supports intelligent reflecting surfaces (IRS). As the

estimation and compensation of the end-to-end phase for each propagation path is prone to errors, imperfect

phase compensation at the IRS is taken into consideration. The performance is derived in terms of symbol

error rate (SER) and outage probability, where the phase error is modeled using the von Mises distribution.

The air-to-air (A2A) channel for

each propagation path is modeled as a single dominant line-of-sight (LoS) component, and the results are

compared to the Rician channel model. The obtained results reveal that the considered A2A model can be

used to accurately represent the A2A channel with Rician fading.