An air search for the missing Malaysia Airlines jet was suspended for a day due to stormy weather on Tuesday as the painstakingly slow sonar scanning of the targeted patch of seabed continued.

Up to 10 planes were to scour the ocean surface for debris on Tuesday over an area covering 49,500 square kilometers (19,000 square miles) centered 1,600 kilometers (1,000 miles) northwest of the Australian west coast city of Perth, the search coordination center said in a statement.

But the center later said the planes would be grounded in Perth due to poor weather related to a tropical cyclone developing off the Australian coast to the north.

“It has been determined that the current weather conditions are resulting in heavy seas and poor visibility, and would make any air search activities ineffective and potentially hazardous,” the center said in a statement.

Ten ships would continue the search on Tuesday.

A robotic submarine was on Tuesday finishing its ninth 16-hour mission scanning the silt-covered seafloor since the search for wreckage shifted beneath the waves on April 14.

The center said the U.S. Navy’s Bluefin 21 had so far covered about two-thirds of the 310-square-kilometer (120-square-mile) seabed search zone, creating a three-dimensional sonar map of any debris. Nothing of interest had been found.

The 4.5-kilometer (2.8-mile) deep search area is a circle 20 kilometers (12 miles) wide where searchers calculated a suspected black box beacon heard on April 8 is probably located. The Boeing 777’s beacons were only designed to transmit signals for 30 days after a crash and their batteries are now assumed dead.

The search coordination center said the sonar scan of the seafloor in that area was expected to be completed sometime this week.

Malaysian Defense Minister Hishammuddin Hussein has said that even if no debris was recovered, the scope of the search may be broadened or other assets may be used.

Radar and satellite data show the jet carrying 239 passengers and crew veered far off course on March 8 for unknown reasons during a flight from Kuala Lumpur to Beijing. Analysis indicates it would have run out of fuel in the remote section of ocean where the search has been focused. Not one piece of debris has been recovered since the massive multinational hunt began.

There have been numerous leads, but all have turned out to be false. The most promising development came when four underwater signals were detected April 5 and 8. The sounds were consistent with pings that would have been emanating from the plane’s flight data and cockpit recorders’ beacons before their batteries died.

(AP)