American Airlines Boeing 787-8 in Charleston

If Qatar Airways seriously wants to form a relationship with American Airlines Group Inc.  (AAL) , it should stay away from a plan to let British Airways PLC use its aircraft and crews to fly through a possible flight attendant strike, American Airlines pilots said.

"Qatar Airways' offering to perform struck work against British Airways aircrew families {provides} a clear example of business relationship dysfunction," said Dennis Tajer, spokesman for the Allied Pilots Association, which represents American's 15,000 pilots.

Such a deal would "dash any hope of {American} ever developing a positive business relationship with {Qatar}," Tajer said.

"The possibility of developing a positive business relationship always exists, but only when Qatar Airways agrees to play by the rules, to stop peddling their influence against our company using ill-gotten funds and to stop trying to undermine workers' rights to negotiate a fair and equitable workplace," he said.

About 83% of American Airlines workers are union members.

On Thursday, American reported in filing with the Securities and Exchange Commission that Qatar's CEO had told American CEO Doug Parker he wants to acquire 10% of American's shares.

Qatar said subsequently that it plans an initial investment for up to 4.75% of American shares, the maximum American permits without advance notice to its board.

Qatar said it "believes in American Airlines' fundamentals and intends to build a passive position in the company with no involvement in management, operations or governance."

American shares closed Wednesday at $48.43. Shares opened Thursday, after Qatar's interest was reported, at $50.50. Shares closed Friday at $48.63, apparently a sign that investors have shrugged off the possibility of a significant impact from Qatar's bid.

On Thursday, the British Civil Aviation Authority said British Airways had requested approval to "wet lease" nine Qatar aircraft from July 2 through July 16, the dates of a proposed strike by some British Airways flight attendants.

Wet leases involve leasing aircraft with crews to operate them.

Qatar owns 20% of International Consolidated Airlines Group SA (ICAGY) , which owns British Airways.

Qatar's bid to invest in American has gotten a thumbs down not only from the APA, but also from the Association of Professional Flight Attendants, which represents American's flight attendants; the Air Line Pilots Association, which represents pilots at most U.S. airlines, and from Parker.

American, Delta Air Line Inc. (DAL - Get Report) , United Continental Holdings Inc. (UAL - Get Report) and most of their unions have opposed the rapid expansion of Qatar Airways, Etihad Airways and Emirates in the U.S. because the three Middle East carriers are heavily subsidized by their governments, in violation of the Open Skies agreements that have enabled their U.S. expansion.

In a letter to employees on Thursday, Parker said American finds Qatar's interest "puzzling given our extremely public stance on the illegal subsidies that Qatar, Emirates and Etihad have all received over the years from their governments.

"While anyone can purchase our shares in the open market, we aren't particularly excited about Qatar's outreach," Parker wrote.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.