MANILA, Philippines – (UPDATE) The United States has dispatched two cargo helicopters to help in search and rescue operations for a presidential helicopter that went missing in the north Tuesday, the chief of the Philippine Air Force (PAF) said.

The helicopters, which were identified as CH-46 Sea Knight, are expected to arrive at the Loakan Airport in Baguio City Wednesday noon from Zamboanga City, where US troops are preparing for annual joint exercises with Filipino troops, PAF Chief Lieutenant General Oscar Rabena told a news conference in Malacañang Wednesday.

Rabena said the PAF also dispatched five helicopters, including Vietnam War era UH-1H or Hueys to look for the Bell 412 presidential chopper that was carrying two pilots and five Palace staff, including press undersecretary Jose Capadocia, appointments secretary Marilou Frostrom, the President’s senior military aide Brigadier General Carlos Clet.

The Bell 412 was declared missing late Tuesday evening after it failed to land in Ifugao province after it took off from the Loakan Airport at 4:20 p.m.

Also on Tuesday, a PAF Fokker F-27 was dispatched to track down an emergency signal that was believed to have come from the Bell 412, but there have been no sighting so far of the missing aircraft, said Major General Jovito Gamad, PAF chief of staff.

The missing Bell 412 chopper is equipped with a global positioning system, navigational and weather instruments, an onboard radar, and an emergency locator transmitter, Lieutenant Colonel Ernesto Torres, Jr. said, adding that it is rated for day and night instrument flight rating.

The chopper was purchased brand new and was delivered in 1996, and its latest Certificate of Airworthiness was issued on February 10 and set to expire Feb. 10, 2010, Torres said.