Reports of rising dissatisfaction with airline service, near collisions in midair and other signs of deteriorating air safety could hardly come as a surprise to close observers of our aviation system.

If these problems have shocked many Americans, it might be because too little attention has been focused on one of the major causes. The truth is that the federal government has allowed the system to be overwhelmed by predictable increases in air travel and bears much of the blame for its dangerous inadequacies.

The federal responsibility arises largely from an 8 percent excise tax on airline tickets -- a tax that many air travelers might not realize they're paying. If you buy a $300 airline ticket, you pay $24 into an Aviation Trust Fund to help finance a safe, dependable and convenient aviation system. This fund collects $4 billion a year. It has a balance of $9 billion and an uncommitted surplus of nearly $6 billion, which lies idle as billions of dollars' worth of airport construction is delayed for lack of funding.

Unfortunately, the Reagan administration and some members of Congress have been inclined to maintain an aviation surplus as a way to make our staggering budget deficit look a little smaller than it actually is. But money collected from aviation users legally must be used for aviation. We should use it that way, without delaying tactics, or cut the tax.

The failure of the administration and Congress to make proper use of the fund has amounted to neglect of the system. That neglect could endanger the lives of air travelers. It clearly has added to the airport congestion and confusion that have given rise to the current chorus of complaints from airline customers.

We knew that air-passenger numbers would soar when we deregulated the aviation industry in 1978, clearing the way for all-out price competition. Yet our government has almost passively watched those numbers rise from 240 million in 1978 to 418 million last year -- a dizzying rate of growth that has far outstripped the capacity of the system.

Airports still aren't being built or expanded fast enough to catch up with demand. The Department of Transportation's current plan to hire 955 air-traffic-control employees still leaves that work force slightly below the level reached before the controllers' strike in 1981. An ambitious program to modernize air-safety equipment is running well behind schedule.

Blame for airline problems can be shared by the administration, Congress and other groups, including the hotly competing airlines themselves. But the important thing is that we all learn a lesson from the current aviation mess. We must stop fussing over stopgap approaches to chronic problems and stinting on aviation improvements and start working together on a plan for the future of aviation. That plan should be worked out by government and industry and spelled out in legislation that will prevent any return to familiar patterns of neglect.

The Senate Commerce Committee has begun this process by approving a bill to increase trust-fund outlays for airport improvements from the current $1 billion a year to $1.6 billion in 1988 and $1.8 billion in 1990. The bill, which predates the Transportation Department's move to hire more controllers, would write that expansion into law. Just as important, it nearly doubles the funding of programs to replace aging air-traffic-control computers, navigational aids and communications systems. It increases those outlays to $1.5 billion next year and $1.75 billion in 1990.

Our related "truth in scheduling" bill prohibits the use of unrealistic flight schedules, establishes a consumer-complaint hot line and initiates other reforms to help ensure that airline passengers reach their destinations safely, on time and with their baggage. The same bill directs the Transportation Department to form a blue-ribbon panel of aviation experts to determine safe and efficient levels of air traffic for the future.

Competitive fares have put the benefits of air travel within the reach of many Americans. The resulting problems have been building for nearly a decade, and no one can promise to end them overnight. But it is high time for the government to begin catching up with its obligations to the flying public.

The writer, a Democratic senator from Kentucky, is chairman of the aviation subcommittee of the Senate Commerce Committee.