Senior government air traffic controllers would make more salary than senators, get two raises a year that exceed the inflation rate, receive 30 percent differentials and retire at age 50 under legislation pending in Congress.

The bill, sponsored by Sen. Charles McC. Mathias (R-Md.), Rep. Bill Clay (D-Mo.) and 15 co-sponsors, would start the Federal Aviation Administration trainees at $22,266 and put senior controllers at $73,240, just $6,000 below Vice President Bush's salary. (The average white-colalr federal worker gets about $22,000 per year, and top federal career executives are limited to a $50,112.50 pay maximum).

Normally a proposal of this kind, in a budget-cutting Congress, would have as much chance as an ice cube dropped in a pan of boiling water. President Reagan and Congress are talking about reducing cost-of-living raises for retirees, holding federal workers to a 4.8 percent raise this October and whacking the size of many agencies and programs. But this bill is a little different.

The legislation covers (or would cover) the nation's 17,000 air traffic controllers. It would set up special pay and benefits for them, independent of the rest of the federal bureaucracy. The controllers are the nation's aerial traffic cops, doing tough, specialized work. Many say they are frustrated and worry about burning out.

Such talk always catches the ears of members of Congress who, as a breed, probably do more flying than any other group in the nation. If you doubt, check the freebie VIP parking spaces at Dulles and National airports: They are always ful of congressional cars. Legislators oft-times kick the FAA (which employs the controllers) but you rarely hear an unkind comment about the controllers.

This is what the Clay-Mathias bill would do for the controllers:

Trainees who now start at $12.266 (the Grade 5 level) would go into a new pay system with a starting salary of $22.266.

Top pay for controllers would be $73,420, independent of any "caps" on salaries of other federal civil servants.

All FAA controllers would get inflation adjustments each April and October. For each 1 percent increase in the cost of living, they would get a 1.5 adjustment.

Controllers would get a 20 percent night differential 25 percent for weekend work and 30 percent for any shifts after midnight.

The standard 40-hour government work week would be shortened, for controllers, to 32 hours.

Controllers could retire after 20 years service with an annuity equal to 75 percent of their highest annual gross pay. Those who quit even earlier would take a pension reduction. Those who worked more than 20 years would get even higher pensions.

The Professional Air Traffic Controllers Organization (PATCO), which represents all 17,000 controllers, says it has 14,500 dues-paying members. PATCO dues are steep by government union standards. Members pay 1.5 percent of the salary for the first step of their GS grade, plus initiation fee of $500. PATCO is affiliated with the Marine Engineers Beneficial Association, AFL-CIO.

Controllers are working under terms of a contract that expired earlier this month. Talks between PATCO and the FAA have been recessed until April 6, when FAA should have a new, Reagan-appointed leader.

Many of the things PATCO is demanding from the FAA -- pay changes, differential changes, retirement changes -- can be granted only by Congress. There has been talk of some kind of job action (it has happened before) to get the attention of Congress and the public. Some people think the big Easter travel season is a likely time unless progress has been made.

To complicate matters -- particularly if you happen to be a member of the FAA negotiating team -- the controllers' organization is one of the very few federal unions that endorsed Ronald Reagan for the presidency before he was elected.