After two, scrappy, markup sessions yesterday, members of the House Aviation subcommittee are scheduled to meet again today on legislation to lift the mandatory retirement age of 60 for commercial airline pilots.

The legislation, as modified yesterday, would lift the retirement age to 61 1/2 immediately and authorize the National Institute of Health to study the relevant medical data for a year to see if it was a good idea. If it were not, the mandatory retirement age would revert to 60.

The subcommittee broke up last night while considering a motion by Rep. William H. Harsha (R-Ohio) to put off further consideration of the legislation until Sept. 10. The delay would provide members time to "understand" the legislation, he said adding "we're not realizing what we're doing."

The members twice before had rejected motions to defer action until Sept. 11 and for three legislative days. They also rejected on an 8-14 vote an amendment proposed by Rep. Barry M. Goldwater Jr. (R-Calif.) to leave the retirement age where it is and let NIH study the issue and report its findings to Congress. "I think it's premature to act and then study," he said.

While more is known about the aging process than in 1959 when the Federal Aviation Administration first issued the age 60 rule, not enough is known to "move in this direction and change the rule," he said.

There has been intense lobbying on behalf of the bill by pilots who have argued that retirement at age 60 is arbitrary and robs the airline system of the most experienced pilots. Although FAA officials agree the age is arbitrary, any age would be, they say. Further, they cite medical opinion showing that most persons suffer from measurable advancing cardiovascular disease and psychophysiological performance by the time age 60 is reached.