Two planes came within 100 feet of colliding at Fort Lauderdale-Hollywood International Airport after one missed its turn onto a taxiway and entered the runway where the other was about to land, federal authorities said.

Air traffic controllers noticed a plane entering a runway Wednesday as Delta Flight 1489 approached the same runway for a landing, Federal Aviation Administration spokeswoman Kathleen Bergen said.

The controllers alerted the Delta crew to pull up and circle the airport to avoid United Flight 1544, which had missed a turn onto another taxiway, Bergen said.

Investigators were focusing on what caused the United flight to veer into Delta's right of way, Bergen said.

Spokeswomen for Atlanta-based Delta Air Lines Inc. and Chicago-based UAL Corp.'s United Airlines did not immediately return messages Thursday seeking comment.

The near-miss, or "runway incursion" in FAA terminology, is under investigation, Bergen said.

The Fort Lauderdale-Hollywood airport had three runway incursions during the 12 months that ended May 31, according to FAA records. Two were blamed on pilot error and the third was ruled an air traffic control error. Nationwide, the FAA reported 330 runway incursions in fiscal year 2006.