The Air Force's newest helicopter might be too big and vulnerable for its intended role, according to one critic.

On November 9, the Air Force announced that it had awarded Boeing a $10 billion contract to build 141 operational HH-47 helicopters for search and rescue, a role now performed by around 100 much smaller, nimbler Sikorsky HH-60G Pavehawks. The first HH-47s will reach frontline squadrons in 2012.

Traditionally, search and rescue targeted fighter pilots shot down just behind enemy lines. In recent years, the mission has evolved to include reinforcement of embattled soldiers, disaster relief and the evacuation of civilians from war zones, such as was undertaken by U.S. military chopper pilots in the early days of the Israeli invasion of Lebanon. "We have identified a lack of speed, range and survivability against future threats [in the HH-60]," said Lieutenant Colonel David Morgan, an Air Force officer formerly associated with the replacement chopper program. "The aircraft is not large enough to be able to recover the number of survivors that we want."

With that in mind, the Air Force picked the 25-ton (maximum weight) HH-47 over the 15-ton Lockheed Martin US-101 and the 14-ton Sikorsky S-92 to replace the 11-ton HH-60. But trading up to a bigger bird has drawbacks, says one member of the Air Force rescue community.

Due to its size, the HH-47 is "a tailor-made [Rocket-Propelled Grenade] target," says the airman, who requested anonymity since he is not authorized to speak to the press. "It's big and can't maneuver quickly, making it easier to hit by the skilled RPG gunners we face in Afghanistan and Iraq. The smaller, more maneuverable aircraft ... are better able to defensively maneuver to complicate the targeting efforts of our enemies. If you scour the news reports of helicopter shoot-downs in Iraq and Afghanistan, you'll see that most were caused by small arms or RPGs or both -- and many of those were -47s, including the famous SEAL incident last summer. The -47 is also louder, which gives those gunners more warning that we're coming."

Chinooks in Iraq usually operate only at night after one Chinook was shot down in broad daylight in 2003, killing 15 soldiers. Another 17 people were killed in the June 2005 downing of a Chinook in Afghanistan -- the "SEAL incident" the airman refers to.

"Since it is so big, [the HH-47] can't fit into nearly as many [Landing Zones] as the -60, -92 or -101," the airman continues. "What this means is that the helo will have to hover and use the hoist or some other means to extract the isolated person. A helicopter in hover is the most vulnerable any aircraft can be, so it's no surprise that crews ... prefer to land, but the -47 will limit their options in this regard. Alternatively, the survivors would have to evade to a large LZ, placing them at greater risk of being captured or killed."

Boeing, for its part, stresses the basic Chinook's extensive record in Iraq and Afghanistan as proof of its suitability. "The tandem rotor, heavy-lift, high-altitude HH-47 is based on the CH/MH-47 Chinook transport helicopter," a statement reads. "[It has] performance capabilities that have been widely demonstrated in the ongoing global war on terrorism and in numerous U.S. and international humanitarian relief operations."

Boeing officials could not be reached for further comment before deadline.