What are the US MQ-9 Reaper drones that have been flying over Gaza?

(Reuters) - Several U.S. MQ-9 Reaper drones have been orbiting over Gaza amid Israeli strikes and military activity there, U.S. officials and a source have told Reuters, and the flights are part of an effort to help locate hostages, 10 of whom are said to be from the United States.

Below is a description of the MQ-9 drone based on information from the Air Force and its maker, General Atomics.

WHAT IT DOES AND WHO OWNS IT:

The General Atomics MQ-9 Reaper unmanned aerial vehicle can loiter at altitudes of around 50,000 feet for more than 27 hours, gathering intelligence with sophisticated cameras, sensors and radars. It has a 66-foot (20.12 m) wingspan, a Honeywell engine, can carry 3,900 pounds (1769 kg) of fuel and has a maximum speed of 240 knots (444 kph).

The Reaper, which entered service with the U.S. Air Force 16 years ago, can be equipped with weapons such as air-to-ground missiles.

MQ-9s have also been bought by the U.S. Department of Homeland Security, NASA, the UK Royal Air Force, the Italian Air Force, the French Air Force and the Spanish Air Force.

WHAT WAS IT DOING IN GAZA?

Officials say the flights there were unarmed and used onboard sensors to search for hostages. The aircraft can carry high-powered cameras, including those that can spot heat or operate with little to no visible light.

According to reports, at least six of the aircraft have been used, and their flight paths have focused on southern Gaza. Amelia Smith, an aviation researcher cited by the New York Times, said the Reapers typically loitered over the area for about three hours, flying at an altitude of about 25,000 feet.

Officials said it was thought to be the first time U.S. drones have flown over Gaza.

WHAT ARE THE ADVANTAGES OF DRONES?

Drones are generally less expensive than crewed aircraft with similar capabilities, and are safer for operators because they do not require a pilot. Unlike most other aircraft, drones can loiter for hours gathering intelligence. They cost about $3,500 per flight hour, compared with about $8,000 per flight hour to operate, for example, an F-16, according to General Atomics.

According the U.S. Air Force, four MQ-9 aircraft with sensors, a ground control station and a satellite link cost about $56.5 million.

CAN AN MQ-9 DEFEND ITSELF?

General Atomics says the MQ-9 has "demonstrated an air-to-air weapons capability" in Air Force tests. It can also be equipped with a "Self Protect Pod" that can detect threats and deploy countermeasures against surface-to-air weapons.

(This story has been refiled to add a dropped word in the secon sub head)

(Reporting by Chris Sanders, Mike Stone and Gerry Doyle; Editing by Nick Macfie)