P is an interstate trucking company with several hundred terminals nationwide. P hired Moyer, the complainant, as a truck driver in 1978. On February 29, 1988, while returning to the terminal, Moyer's truck suffered a mechanical breakdown. Moyer contacted a P dispatcher who instructed him to go to the nearest telephone and, presumably, inform the company's mechanics of his situation. P hired Moyer, the complainant, as a truck driver in 1978. On February 29, 1988, while returning to the terminal, Moyer's truck suffered a mechanical breakdown. Moyer contacted a P dispatcher who instructed him to go to the nearest telephone and, presumably, inform the company's mechanics of his situation. While descending from the truck, Moyer aggravated a pre-existing medical condition. Moyer contacted the dispatcher who once again told Moyer to go to a telephone, call the mechanics, and return to the truck to await help. Another Yellow Freight driver stopped to assist Moyer and eventually drove him to the terminal. At the terminal, Moyer told the dispatcher that he was ill and needed to go to a hospital. The dispatcher insisted that Moyer inform company mechanics of the breakdown and report the location of the truck. Eventually, an ambulance arrived, and medical personnel transported Moyer to the hospital. P placed Moyer on a four-day suspension for returning to the terminal and leaving the truck unattended and for failing to follow company procedure for drivers experiencing mechanical breakdowns. Between June and October 1988, P issued Moyer four warning letters for being unavailable for dispatch without an excuse. The final warning was for when Moyer testified at a grievance proceeding for Robert E. Lee, a fellow employee. Lee challenged P's decision to fire him following his receipt of a letter from P that allegedly gave him 72 hours to appear at the terminal. Moyer testified that Lee had a back injury and had been unable to respond to the company's demand. After issuing this last letter, P terminated Moyer on November 9, 1988. P filed a complaint with D alleging that Yellow Freight had violated §405 by discharging him in retaliation for his refusal to drive a truck while he was ill on February 29, 1988. D notified P of the complaint and requested a full and complete written account of the facts and a statement of P's position in respect to the allegation that Moyer was discharged in reprisal for not operating his commercial vehicle because of illness. In a letter dated March 17, 1989, OSHA's regional administrator informed P that Moyer's complaint has no merit. Moyer objected to OSHA's findings and requested an administrative hearing. After an evidentiary hearing, an administrative law judge recommended D find no violation of §405(b) because, on February 29, 1988, Moyer was not engaged in any activity protected by that provision. The administrative law judge noted that there was insufficient evidence on the nature of the Lee proceeding to find a violation of another provision, §405(a). D agreed with the administrative law judge for §405(b) but concluded Moyer's discharge violated §405(a). D concluded there was sufficient evidence in the record as a whole to determine Lee's grievance proceeding related to a violation of a commercial motor vehicle safety rule. D ordered Moyer reinstated. P appealed seeking review of D's decision finding a violation of § 405(a) as well as her order denying reopening of the administrative hearing.