Federal safety officials are faced with twin investigations in the crashes of two helicopters that plunged into the East River (search) within minutes of taking off this past week.

A total of 15 people survived the two crashes. One remained in critical condition Saturday.

"We're casting a big net right now," National Transportation Safety Board (search) air safety investigator Brian Rayner said Saturday at a news conference.

Rayner was investigating Friday's crash of a helicopter carrying two pilots and six businessmen. The chopper went into the river just after taking off from midtown Manhattan's 34th Street heliport for a flight to Wilmington, Del.

Rayner, echoing comments of NTSB investigators looking into Tuesday's crash of a sightseeing helicopter just a few miles away near the Wall Street heliport, said it was far too early to speculate on what caused the crash.

During 1995-2004, all of New York state averaged about four serious helicopter accidents per year, according to NTSB statistics. The two East River crashes were the state's first this year. There were 179 serious helicopter crashes nationwide in 2004.

Friday's crash involved an aircraft operated by MBNA Corp. that was taking executives to the financial services company's headquarters in Delaware.

Lance Weaver, 50, chief administrative officer for MBNA, said the takeoff was "unremarkable" until the helicopter lost altitude and fell into the river.

One of the MBNA pilots, Mark Schaberg, 56, remained hospitalized Saturday in critical but stable condition at Bellevue Hospital (search), said hospital administrator Peter Schectman. The second pilot and all six passengers were treated and released.

One victim from Tuesday's accident was still in Bellevue on Saturday, listed in serious but stable condition.