The Federal Aviation Administration does not require commercial airliners to carry life rafts on most domestic flights despite the fact that dozens of runways must be approached from over water.

That came clearly into focus with the crash Sunday night of a National Airlines jet into Escambia Bay about three miles short of the Pensacola, Fla., airport. Three people drowned and 55 were rescued. Most of them scrambled aboard a barge that a tug boat operator pushed against the side of the plane.

Life jackets were stowed under all the seats of the National jetliner, as required by FAA regulations, and the seat cushions were designed to float. "Our rationale has been that life rafts are only useful in a deliberate ditching," said FAA spokesman Dennis Feldman. "If it's an emergency, the best thing to do is get the life jacket on and get the hell out."

In the Pensacola crash, everything was normal about the landing except the location. The nose of the Boeing 727 was slightly raised, the landing gear was down, the leading edges of the wings were extended and the power settings were normal, according to early information available to investigators. The plane should have been 1,250 feet above the water at the point of impact, investigators said.

Many passengers have told investigators they thought they were on the ground after an unusually hard landing. "Most people did not take life vests or flotation cushions with them," said Jim King, chairman of the National Transportation Safety Board. "The folks that left were unaware they were in the middle of the water."

When passengers realized where they were, they went back to get life vests and cushions.

The FAA requires that life rafts be on planes flying more than 50 miles from land. Although National and several other airlines have an exemption to that rule for some routes, it is a moot question in this case because Flight 193 to Pensacola from New Orleans would not normally stray more than 50 miles into the Gulf of Mexico.

However, the point remains. Approach and landing accidents account for as much as 65 percent of all aviation accidents in a given year. Dozens of approaches are over water, even at interior airports such as Washington's National and Chicago's O'Hare, and at many coastal cities - New York, Boston and Los Angeles, to name but three.

"This is really the area where water emergency procedures should be aimed," said a knowledgeable official from an airline other than National. "There hasn't been a ditching of a jetliner in the ocean in 15 years."

Investigators are also puzzled as to why the plane came down so far from the end of the runway. Most approach accidents occur when a plane misses the end of a runway by a short distance, usually less than a mile. National Flight 193 was more than three miles from the end of Runway 25.

Visibility was one mile, in fog, with a ceiling of 400 feet, according to investigators. The pilot was making a correct approach as far as weather was concerned, they said.

Runway 25 lacks precision navigation equipment. The pilot derives directions of heading only, not altitude, from the equipment that is available. Most major airport runways provide altitude information as well as heading. Therefore, the pilot had to determine his altitude from one of three altimeters in the aircraft. All three are being examined.

The radar at the airport is also not the newest and does not display an aircraft's altitude as does radar at more frequently used airports.