The MTA fired a subway operator Thursday who broke the rules to rescue a student who collapsed in his train car while spitting up blood -- and union officials blasted the decision.

Quincy Calhoun, 60, was training a student on a No. 5 train in April when the trainee felt chest pain and blacked out as they neared the end of the line in the Bronx, transit documents show.

Calhoun, an Air Force veteran who has worked for the MTA since 1989, said he tried to reach the Rail Communication Center for help but radio problems made it a dead zone, union officials said.

He went onto the tracks, disabled a signal and then split a switch to move the train into the Dyre Avenue station at under 10 mph. Medics then rushed the student to Jacobi Hospital, where he was treated.

"My only concern was getting the student to safety," Calhoun said. "That's what I was thinking about."

The MTA then suspended Calhoun without pay, and said his actions could have derailed the train. Union officials were stunned by the disciplinary action, and said it was the worst case they had seen.

"When I violated rules to save lives on 9/11, I did just what transit good Samaritan Quincy Calhoun did," said Kevin Harrington, a vice president at TWU Local 100 and former train operator.

"The decision is unjust, unfair, and sets a dangerous guide for helping people in distress in the subways."

On Wednesday, an arbitrator said Calhoun did not follow proper safety procedure, and has been disciplined in the past.

"Calhoun has not been truthful," says the arbitration ruling. "Serious inconsistencies in the record do not corroborate the medical emergency on which he relies in defense against these charges.".

Calhoun said he was completely honest in describing what happened to the arbitrator. "I'm very surprised at the ruling," he said. "It is totally unfair."

Harrington said the decision was beyond the realm of reason, and that cats on the tracks get more consideration than sick workers.

"This goes against the whole of Western ethical tradition and the decision borders on the demonic," he said. "This arbitration has failed to see the forest for the trees, and avoided Calhoun's noble motivation."