Complex sentence: Jack had flown back to western New York and the Bell Aircraft Plant in Wheatfield, NY, where the P-39 had been built at the Wheatfield plant but was owned by an organization known as Skylanes Unlimited.
Split into simpler sentences: Jack had flown back to western New York and the Bell Aircraft Plant in Wheatfield, NY. The P-39 had been built at the Wheatfield plant but was owned by an organization known as Skylanes Unlimited.