UPS Seen at ‘Breaking Point’ as Pilots Lament Too Few Aircraft

United Parcel Service Inc. was already in trouble with Wall Street over a long-term investment plan to cope with soaring e-commerce. Now the company is clashing with its pilots union because of a short-term fix for the same challenge.

Aviators are angry that UPS has turned to third-party cargo airlines to help make up for a shortage of aircraft capacity. Accusing UPS of years of poor planning and insufficient investment, the Independent Pilots Association has complained to an industry arbitrator that the courier is violating its labor contract by outsourcing flying that should be done by its own pilots.

“On ...