UPS mechanics
The mechanic union specifically told ALPA and the flight attendant unions NOT to sympathy strike.
The mechanics thought they could strike and bring the company to it's knees all by themselves. Part of the reason is that during that time, there was a lot of internal strife within the mechanic union. I do not remember which union is/was which, but the union that was in control during most of the contract negotiations was viewed as weak and booted out. The new union came in with big expectations and they tried flexing their muscles and went on strike without the assistance of the other unions. They were wrong and the company was able to replace all of the mechanics and keep the airline running.
I am not a mechanic, but I am a union member. I learned a big lesson. Don't believe everything your company tells you. But also don't believe all of the Kool-aide your union serves either.