The RQ-4 provides a broad overview and systematic surveillance using high-resolution synthetic aperture radar (SAR) and electro-optical/infrared (EO/IR) sensors with long loiter times over target areas.

It is used as a high-altitude long endurance (HALE) platform[2] covering the spectrum of intelligence collection capability to support forces in worldwide military operations.

For the GHMD program, the Global Hawk was tasked with maintaining maritime situational awareness, contact tracking, and imagery support of exercise operations.

"[28] On 26 January 2012, the Pentagon announced plans to end Global Hawk Block 30 procurement as the type was found to be more expensive to operate and with less capable sensors than the existing U-2.

[42] On 21 July 2011, the first EuroHawk arrived in Manching, Germany; after which it was scheduled to receive its SIGINT sensor package and undergo further testing and pilot training until the first quarter of 2012.

[49] German defense minister Thomas de Maizière stated EuroHawk was "very important" for Germany in 2012,[44] then referred to the project as being "a horror without end" in his 2013 statement to the Bundestag.

[54] On 5 October 2014, German Minister of Defence Ursula von der Leyen was reportedly considering reactivating the EuroHawk program to test its reconnaissance abilities over a long period at altitudes of up to 20,000 m (66,000 ft).

[55] Germany is considering installing the EuroHawk's SIGINT payloads onto the U.S. Navy MQ-4C Triton Global Hawk derivative, as the electronic and communications intelligence sensors would be more difficult to place on other substitute aircraft.

[58] In April 2015, Northrop Grumman reportedly installed the U-2's Optical Bar Camera (OBC) and Senior Year Electro-Optical Reconnaissance System (SYERS-2B/C) sensors onto the RQ-4 using a Universal Payload Adapter (UPA).

The first version to be used operationally was the RQ-4A Block 10, which performed imagery intelligence (IMINT) with a 2,000 lb (910 kg) payload of a synthetic aperture radar (SAR) with electro-optical (EO) and infrared (IR) sensors.

It is also fitted to the US Army's de Havilland Canada RC-7B Airborne Reconnaissance Low Multifunction (ARLM) crewed aircraft, and is being sold on the international market.

[76] In November 2015, Northrop Grumman selected the Garmin International GSX 70 weather radar to be installed on Air Force Global Hawks.

[citation needed] The visible and infrared imagers share the same gimballed sensor package, and use common optics, providing a telescopic close-up capability.

[citation needed] Following the September 11th attacks, the normal acquisition process was bypassed almost immediately and early developmental Global Hawk models were employed in overseas contingency operations beginning in November 2001.

Since April 2010, they fly the Northern Route, from Beale Air Force Base over Canada to South-East Asia and back, reducing flight time and improving maintenance.

In June 2012, a media report described the Global Hawk, the General Atomics MQ-1 Predator and the MQ-9 Reapers "... the most accident-prone aircraft in the Air Force fleet.

[86] In planning the USAF's FY 2015 budget, the Pentagon reversed its previous decision, shifting $3 billion from the U-2 to the RQ-4 Block 30, which had become more competitive with the U-2 due to increased flying hours.

Factors such as cost per flight hour (CPFH), information gathering rates, mission readiness, adverse weather operational capability, distance to targets, and onboard power still favored the U-2.

It was the first time that they had operated out of a civil-military airport, sharing airspace and runways with commercial aircraft safely without additional restrictions, usually taking off and landing during quieter periods of air traffic.

[104] In 2017, the USAF decided to begin the process of training enlisted airmen to fly the RQ-4 due to a shortage of pilots and an increased demand for the Global Hawk's capabilities.

[107] On 21 April 2021, a Global Hawk was reported to have made a reconnaissance flight in an airspace off the coast of southern Crimea which Russia had temporarily closed up to 19,000 metres (62,000 ft) from Sevastopol to Feodosiya, issuing a relevant NOTAM.

[108] On 22 February 2022, a Global Hawk was reported to have made a reconnaissance flight over Southeastern Ukraine coinciding with a NOTAM order by Ukrainian government and increased Russian military activity.

[109][110] On 24 April 2001, a Global Hawk flew non-stop from Edwards AFB to RAAF Base Edinburgh in Australia, making history by being the first pilotless aircraft to cross the Pacific Ocean.

[111] On 22 March 2008, a Global Hawk set the endurance record for full-scale, operational uncrewed aircraft UAVs by flying for 33.1 hours at altitudes up to 60,000 feet over Edwards AFB.

88 percent of flights were conducted by USAF RQ-4s, while the remaining hours were flown by NASA Global Hawks, the EuroHawk, the Navy BAMS demonstrator, and the MQ-4C Triton.

Approximately 75 percent of flights were in combat zones; RQ-4s flew in operations over Afghanistan, Iraq, and Libya; and supported disaster response efforts in Haiti, Japan, and California.

[71] On 19 June 2019, a U.S. Navy BAMS-D RQ-4A from NAS Patuxent River flying over the Persian Gulf near the Strait of Hormuz was shot down by a 3rd Khordad surface-to-air missile fired from near Garuk, Iran.

[119][120] The two Global Hawks were the first and sixth aircraft built under the original DARPA Advanced Concept Technology Demonstration program, and were made available to NASA when the Air Force had no further need for them.

[130] In January 2012, DAPA announced that it would not proceed with a purchase due to a price rise from US$442M to US$899M, and that other platforms such as the AeroVironment Global Observer or the Boeing Phantom Eye were being investigated.

[citation needed] On 21 November 2014, the Japanese Ministry of Defense officially decided to procure the Global Hawk instead of the General Atomics Guardian ER;[138] Japan has also been interested in the purchase of three aircraft.