Union pilots at UPS are ready to show solidarity with Teamsters workers if there is a strike, which would ground UPS Airlines.

The union representing UPS pilots says they will not cross picket lines if Teamsters drivers and package sorters walk off the job when the current contract expires Aug. 1, resulting in the immediate shutdown of the express logistics company’s global air operations.

UPS (NYSE: UPS) has 3,300 pilots who are represented by the Independent Pilots Association (IPA), a separate union from the Teamsters.

“If the Teamsters are on strike, we will honor that strike and we will not fly,” IPA spokesman Brian Gaudet told FreightWaves.

UPS pilots are allowed under their collective bargaining agreement to honor primary picket lines and did that for 16 days during the Teamsters’ strike in 1997.