Weather, equipment problem delay Logan flights

Peters said the instrument-landing system at Runway 4R failed Tuesday for reasons that are still under investigation. Without the system, the FAA has to shift landings to runways 33L and 15. Those runways can handle instrument landings, but officials prefer to use 4R in bad weather conditions.

To assure safe flights, the FAA has ordered airports across the country to hold Boston-bound flights on the ground until a landing slot opens at Logan. At 3 p.m., the airport has cut the number of landings to 26 an hour, down from the normal rate of more than 60, Peters said.

Peters said that if weather worsens, the FAA may reduce the number of arrivals and may also stop allowing planes to land at Logan entirely.

“If we go below the [safety] minimums, we cannot allow aircraft to land,’’ Peters said. “In effect, today we are limited to one runway for landings and one runway for takeoffs.’’

He said the FAA is closely watching weather conditions.

It is not known how long it will take to repair the instrument-landing system and bring 4R back into service, Peters said.