Modern avionics have made navigation the least of the concerns for any pilot, with computers giving precise route coordinates. Still, how did aircraft navigate before the Global Positioning System GPS became a standard navigation tool? Aircraft used different methods to navigate pre-GPS, including dead reckoning, celestial navigation, and more.
The historyWhen aircraft first took to the skies in the 1900s, flights would use visual aids for all navigational purposes, with very little in the way of hardware. However, with the entry of aircraft into military use, flying at higher altitudes and longer distances, accurate navigation became essential for any flight.

Of course, planes could use onboard radios to communicate with the ground, receiving instructions from the ground crew. Even though this was workable during takeoff and landing, radios had a limited range in terms of distance, meaning communication became impossible once aircraft were a few hundred miles away. Instead, crews used several manual ways to calculate their position.
Celestial navigation was a standard method of finding a plane's location, where navigators would use a bubble sextant to calculate the aircraft's position relative to the sun, moon, or stars. This method was used until the jet age in the 1960s, with early Boeing 747s even having a sextant port on the cockpit roof.
Dead reckoning was another common navigation method on long flights. With this process, navigators would use previously known positions to estimate the plane's current position using speed and flight time. While the weather could hamper these estimates, it was a relatively accurate way to calculate the plane's location.

To better provide information while in flight, ground bases would use a system known as long range navigation (LORAN). Two land-based radio transmitters would send each other signals at a set interval, allowing plane navigators to use the time difference to find their exact location. While this was an ideal solution, weather and frequency disruptions could easily distort the transmission, leaving the crew with unreadable data.
On commercial aircraftPlanes have been flying commercially since the early 20th century, but GPS has only come into active use in the last two decades. Prior to using GPS as we know it, modern aircraft had a number of other tools at their disposal.
Some may recall that flight decks previously used to have navigators onboard, a person dedicated to tracking the aircraft's route and radio communications. This was mainly found on long flights over the ocean, where radar contact could be lost, and fewer diversion airports were available.
Modern avionics, and a push to reduce inflight crew, have resulted in these navigators now no longer being needed on commercial flights. Air Force One, which is a modified 747-200, interestingly still has a navigator in the cockpit due to the aircraft's age. It remains one of the last commercial-made planes to have one, although some military aircraft still use navigators too.

Prior to the jet age, some aircraft used a radio-based system known as Very High Frequency Omni-Directional Range (VOR) flying. In this system, aircraft would receive communications from fixed ground beacons, allowing it to continue its flight path and find its position. This navigation method was quite reliable in areas with radio coverage and continued to be in use until GPS became the norm.
The beginning of the jet age also marked the introduction of a new navigation method: inertial navigation systems (INS). The INS phased out older celestial systems, relying on highly sensitive motion and rotation sensors instead. This marked the first use of partially-computerized navigation sensors, a trend that would continue until GPS became standard on all flights.
The INS systems also made aircraft navigators mostly redundant, which is why no modern aircraft has a navigators seat. The introduction of the inertial navigation system revolutionized flight navigation, allowing pilots to follow set flight paths based on their current positions and take the guesswork out of the calculations.


The advent of GPSGPS, or Global Positioning System, actually came into operation well before it became a mainstay in all cockpits and mobile devices. GPS was initially created for military purposes only, with the project starting in 1973 and the first satellite launching in 1978.
However, in 1983, President Ronald Reagan signed an executive order allowing passenger aircraft to use the system once it was fully operational. The reason to allow GPS for commercial use was due to the recent Korean Air Lines crash in 1983.
KAL007 crashed after it was shot down by Soviet fighter aircraft due to the plane mistakenly entering Soviet airspace on its way to Seoul. In response to the crash, the US authorized the use of GPS for flights to provide for more accurate navigation.
In February 1994, the FAA authorized the use of GPS on aircraft, setting up the next generation of aircraft navigation. Soon after, GPS became available for mobile devices too, which is what makes Google Maps and flight tracking software work.
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A long journeyAll in all, the Inertial Reference System (IRS) is the primary navigational system in a plane today. The self-sufficient process doesn't need any external input to know where it is across the skies. It doesn't consist of any physical leveling and utilizes mathematical algorithms to ensure the accelerometers are constantly in line with the horizon.
Aircraft navigation has come a long way from pilots flying with little information to having everything on a screen before them. While older methods of navigation are gone from the cockpit, pilots still learn many older tools. Dead reckoning continues to be taught to pilots, even if they fly aircraft with GPS. This is because technology can fail, forcing pilots to manage the aircraft manually.


Despite being integral to global air operations for decades, GPS isn't full-proof. For instance, just last month, Qantas crews had been experiencing radio interference and GPS jamming in the Asia-Pacific. Moreover, the pilots had been instructed to fly through these disruptions. While these incidents didn't result in any catastrophes, they highlight the challenges that remain for commercial operators across the skies.
Aircraft navigation continues to evolve even today. Companies are already developing the next generation of technology to allow for autonomous flight. There will undoubtedly be major transitions in this field over the next decade.
What do you think about older navigation methods and how pilots managed their operations before the advent of GPS? What will be the next breakthrough in the aviation industry? Let us know your thoughts on the overall prospects in the comment section!

While officially retired in 2008, the F-117 Nighthawk have continued to fly, unofficially, from Tonopah Test Range (TTR) airfield in Nevada. As explained in a detailed story, back in 2014, after a few videos and photographs had already appeared online, the U.S. Air Force admitted that the Nighthawk was kept in a â€œType 1000” storage at TTR which meant that the type is had to be maintained until called into active service. Desert conditions of Nevada are perfect for maintaining the stealth jets in pristine conditions (due to the low level of humidity and hence, lower probability of corrosion), hence the reason to operate the enigmatic aircraft from TTR.
In July 2016, we published a video showing two F-117s flying together, filmed from the distant hills east of Tonopah Test Range, then, in 2017, the U.S. Air Force announced the decision to retire the fleet permanently, once and for all. In fact, “in accordance with the National Defense Authorization Act of 2017, passed Dec. 23, 2017 the Air Force said it would remove four F-117s every year to fully divest them. However, the aircraft continued to be spotted, even more than it had happened until then, with the Nighthawks also deploying to several U.S. bases to carry out Dissimilar Air Combat Training with other U.S. types. Until 2021, when the U.S. Air Force published the first official images of the type still involved in flight operations on the DVIDS (Defense Visual Information Distribution Service) network.

Anyway, it’s no longer a secret that 15 years after being officially retired, the F-117s are being actively used not only for training purposes as adversary aircraft and cruise missile surrogate, but also for research, development, test and evaluation. As a consequence, they continue to be spotted as they fly their missions across the U.S., as happened on Friday Apr. 21, 2023, when aviation photographer Alex filmed two Nighthawks flying low level over the Eastern Sierras on the famous Sidewinder low level route.
“I believe this is the lowest they have been observed flying along the low level route,” Alex told us in a message. “I was blown away when I heard them call on the radio, and even more amazed to watch them fly past.”
Take a look by yourself at the incredible footage Alex posted:

Dave “Bio” Baranek enjoyed a successful and satisfying 20-year career in the Navy, starting with assignments to F-14 squadrons as Tomcat Radar Intercept Office (RIO) and the elite TOPGUN training program, and later assignment to the Joint Chiefs of Staff and the US 7th Fleet. At one point, he commanded an F-14 Tomcat fighter squadron, responsible for nearly 300 people and 14 aircraft worth about $700 million. He completed his career with 2,499.7 F-14 Tomcat flight hours and 688 carrier landings.
The Grumman F-14A Tomcat was the first of the American teen-series fighters, which were designed incorporating air combat experience against MiG fighters during the Vietnam War. However despite the fact that the F-14 was a formidable dogfighter, what made the Tomcat unique was fleet air defense role. To accomplish this mission the aircraft was fitted with a powerful weapons system known as the AWG-9 which was able to support the AIM-54 Phoenix that provided an unprecedented one-hundred mile range and included a small onboard radar to guide itself to the target during the final phase of flight.

Because of the AWG-9’s impressive capabilities a RIO in the back seat of the F-14 was required to optimize it in various stages of a mission.
Of all the training environments faced by a Tomcat crew, possibly the most challenging one for a RIO was that of a so called MISSILEX (a Missile Exercise, where a “live” missile is launched against a drone acting like an airborne target). In his book Before Topgun Days Baranek tells the story of the second AIM-7 Sparrow he ever shot: in Dec. 1982, while attached to the VF-24 Fighting Renegades Fleet squadron, he and Lieutenant Commander Steve “Drifty” Smith were in fact chosen to launch a Sparrow at a target over the Pacific Ocean off Southern California.
Since the missile shot had to follow a test and evaluation (T&E) profile, both drone and Tomcat were required to fly supersonic, an aspect that added more challenges to the already complex drill scenario.
As they approached the launch range, Drifty shoved the throttles to Zone 5 (maximum afterburner for F-14A) and they accelerated through Mach 1, then an AQM-37 target drone was launched by an A-6 Intruder operated by the Pacific Missile Test Center.

NASA awarded a contract to Lockheed Martin to study the feasibility of building a hypersonic propulsion system for a concept intelligence, surveillance and reconnaissance (ISR) aircraft dubbed the SR-72 using existing turbine engine technologies.
As explained by James C. Goodall in his book 75 years of the Lockheed Martin Skunk Works, the contract provides for a parametric design study to establish the viability of a turbine-based combined cycle (TBCC) propulsion system consisting of several combinations of near-term turbine engine solutions integrated with a very low-Mach ignition dual-mode ramjet (DMRJ) in the SR-72 vehicle concept.
The SR-72 is envisioned as an unmanned, reusable hypersonic ISR and strike aircraft capable of Mach 6 flight, or nearly double the speed of its predecessor, the SR-71 Blackbird. NASA is funding the validation of a previous Lockheed study that found that speeds up to Mach 7 could be achieved with a dual-mode engine that combines turbine and ramjet technologies.
Skunk Works was responsible for developing the SR-71 Blackbird, which was able to achieve Mach 3.2 with specially designed Pratt & Whitney J58 engines. The power plants were able to function as a low-speed ramjet by redirecting intake air around the engine core and into the afterburner starting at Mach 1.4 to full turboramjet from Mach 2.5 and above.
Potential adversaries are working on technologies to counter USAF fighter and bomber stealth capabilities. The service sees hypersonic vehicles as the next logical step in that arms race.
The USAF has a hypersonics roadmap that envisions fielding a hypersonic strike weapon, to succeed the X-51 Waverider proof-of-concept demonstration. The Waverider successfully launched from a B-52 and was powered to Mach 4.8 by a booster rocket. The X-51 then accelerated to Mach 5.1 after igniting its ramjet engine.
The roadmap envisions a follow-on program calling for a reusable unmanned aircraft with Mach 6 speeds. At that speed, intelligence can be gathered or weapons delivered before enemy air defenses are even alerted.

Both the Air Force Research Laboratory (AFRL) and DARPA have been after a low-speed ramjet for years. The agencies’ HTV-3X program demonstrated that a ramjet that could operate below Mach 3. That inspired Lockheed to partner with Aerojet Rocketdyne to develop a way to use off-the shelf engines like the F100 or F110 for short bursts of acceleration beyond Mach 2.2 in an attempt to close the gap between the two propulsion technologies. This study is to see if the SR-72 technology demonstrator can use existing technologies to create a dual-mode ramjet that in theory can light up at Mach 2 to 2.5. The key to this whole effort is whether they can do it and finding the required technologies so they can plan for a program in which they can develop the program as envisioned.
The problem with hypersonic propulsion has always been the gap between the highest-speed capability of a turbojet and the lowest speed of a ramjet. Most ramjets cannot achieve ignition below Mach 4. Turbine engines typically can accelerate to only Mach 2.2, below speeds at which a ramjet could take over and continue acceleration. Therefore, NASA and Lockheed must develop either a turbine engine that can accelerate to Mach 4 or a ramjet that can function at speeds within a turbine engine’s envelope. Design engineers from both Lockheed Martin and NASA are looking for a turbine-based combined system where at low speeds you have a turbine providing power, then at higher speeds a ramjet or scramjet takes over. The target is to be able to go up to Mach 7 then transition back to the turbine to land it on a runway and recover it. The problem is how you can get the vehicle to fly fast enough to ignite the DMRJ and then have the DMRJ take over.
NASA is considering several existing turbofan engines for use in the project, including the Pratt & Whitney F100-PW-229 that powers both the Boeing F-15 and Lockheed Martin F-16, among other aircraft. The General Electric F414 used by the Boeing F/A-18E/F Super Hornet also is being studied, along with the supersonic turbine engine for long range (STELR) engine conceived by AFRL.
If the study is successful, NASA wants to fund a demonstration program. Lockheed Martin would test the dual-mode ramjet in a flight research vehicle, and try to find solutions to issues like engine packaging and designing the thermal management system.
As with all programs being developed in the late 2019/early 2020-time frame, to include the SR-72 program, canceled programs due to budget cuts and reduced manpower available to this and other critical programs under development.

Rolls-Royce has begun testing its F130 engine that will replace the existing engines in the US Air Force’s B-52 Stratofortress bomber fleet.
The testing at the company’s outdoor facility at the NASA Stennis Space Center in Mississippi marks the first time the new engines are trialed in the dual-pod configuration, as each B-52 requires eight engines in four pods.
Under the latest effort, Rolls-Royce is focusing on the F130’s crosswind aerodynamic flow and the operability of its digital control system with the strategic bomber.
Data from the ongoing trials will be assessed over the coming months.
Extends B-52 Life for 30 Years“We are excited to begin this milestone testing program, the first step for what will be decades of successful engine operation for the United States Air Force B-52 fleet,” Rolls-Royce Defense Program Director Candice Bineyard stated.
Rolls-Royce is closely collaborating with Boeing “to ensure the engine testing and integration process run smoothly.” Boeing is managing the B-52 aircraft modernization program and overall engine integration.
The new engine “will result in higher fuel efficiency, reduced air refueling requirements, and significantly lower maintenance costs for the B-52 fleet,” Bineyard explained.
Overall, the F130 is expected to extend the fleet’s life by three decades.

A Boeing 737-8 MAX straight from the factory was flying when the pilot declared an emergency, telling the ATC tower that they had no autopilot trim and no electrical trim system and had to trim the aircraft manually.
Southwest Airlines Boeing, registration N8844Q, was flying from Phoenix Sky Harbor International Airport (PHX) to William P. Hobby Airport (HOU). The pilot reported a trim and autopilot issue and declared an emergency, requesting a return to the airport.
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The crew requested to level off at 11,000 feet and began running checklists. The pilot and ATC tower calmly communicated the situation and were able to navigate back to the airport safely. The plane returned to Phoenix about 23 minutes after departure and the pilot was able to navigate back to the airport, trimming manually, and safely land without any injury to the 164 passengers on board or damage to the aircraft.
The plane had arrived in Phoenix on its delivery flight from Boeing Field the day before and successfully entered service roughly 14 hours later, according to the Aviation Herald. Trimming an aircraft means adjusting the aerodynamic forces on the control surfaces, allowing the pilot to maintain the set attitude without using any control input.

Air racing enthusiasts are inviting the community and race fans from all over the world to join them in sending the Reno Air Races off in style one last time.
The organization will continue to discuss the future of the races but are forever grateful for the decades spent at the Reno-Stead Airport and their partnership with the Reno Tahoe Airport Authority.
The final event is set to return more than 150 planes and pilots as well as several 'hands-on' displays and experiences.

Hydrogen-branded plane, equipped with the largest hydrogen fuel cell ever to power an aircraft, made its maiden test flight in eastern Washington, co-founder and CEO Paul Eremenko declared the moment the dawn of a “new golden age of aviation.”
The 15-minute test flight of a modified Dash-8 aircraft was short, but it showed that hydrogen could be viable as a fuel for short-hop passenger aircraft. That is, if Universal Hydrogen — and others in the emerging world of hydrogen flight — can make the technical and regulatory progress needed to make it a mainstream product.
Dash-8s, a staple at regional airports, usually transport up to 50 passengers on short hops. The Dash-8 used in Thursday’s test flight from the Grant County International Airport in Moses Lake had decidedly different cargo. The Universal Hydrogen test plane, nicknamed Lightning McClean, had just two pilots, an engineer and a lot of tech onboard, including an electric motor and hydrogen fuel cell supplied by two other startups.

The stripped-down interior contained two racks of electronics and sensors, and two large hydrogen tanks with 30 kg of fuel. Beneath the plane’s right wing, an electric motor from magniX was being driven by the new hydrogen fuel cell from Plug Power. This system turns hydrogen into electricity and water — an emission-free powerplant that Eremenko believes represents the future of aviation.
The fuel cell operated throughout the flight, generating up to 800kW of power and producing nothing but water vapor and smiles on the faces of a crowd of Universal Hydrogen engineers and investors.
“We think it’s a pretty monumental accomplishment,” Eremenko said. “It keeps us on track to have probably the first certified hydrogen airplane in passenger service.”
Aviation currently contributes about 2.5% of global carbon emissions, and is forecast to grow by 4% annually.

The test flight, which was a success, doesn’t mean entirely zero-carbon aviation is just around the corner.
Beneath the Dash-8’s other wing ran a standard Pratt and Whitney turboprop engine (notice the difference in the photo above), with about twice as much power as the fuel-cell side. That redundancy helped smooth a path with the FAA, which issued an experimental special airworthiness certificate for the Dash-8 tests in early February.
One of the test pilots, Michael Bockler, told TechCrunch that the aircraft “flew like a normal Dash-8, with just a slight yaw.” He noted that at one point, in level flight, the plane was flying almost entirely on fuel cell power, with the turboprop engine throttled down.
“Until both motors are driven by hydrogen, it’s still just a show,” said a senior engineer consulting to the sustainable aviation industry. “But I don’t want to scoff at it because we need these stepping stones to learn.”
Part of the problem with today’s fuel cells is that they can be tricky to cool. Jet engines run much hotter, but expel most of that heat through their exhausts. Because fuel cells use an electrochemical reaction rather than simply burning hydrogen, the waste heat has to be removed through a system of heat exchangers and vents.
ZeroAvia, another startup developing hydrogen fuel cells for aviation, crashed its first flying prototype in 2021 after turning off its fuel cell mid-air to allow it to cool, and was then unable to restart it. ZeroAvia has since taken to the air again with a hybrid hydrogen/fossil fuel set-up similar to Universal Hydrogen’s, although on a smaller twin-engine aircraft.
Mark Cousin, Universal Hydrogen’s CTO, told TechCrunch that its fuel cell could run all day without overheating, thanks to its large air ducts.
Another issue for fuel cell aircraft is storing the hydrogen needed to fly. Even in its densest, super-cooled liquid form, hydrogen contains only about a quarter the energy of a similar volume of jet fuel. Wing tanks are not large enough for any but the shortest flights, and so the fuel has to be stored within the fuselage. Today’s 15-minute flight used about 16kg of gaseous hydrogen — half the amount stored in two motorbike-sized tanks within the passenger compartment. Universal Hydrogen plans to convert its test aircraft to run on liquid hydrogen later this year.

Eremenko co-founded Universal Hydrogen in 2020, and the company raised $20.5 million in a 2021 Series A funding round led by Playground Global. Funding to date is approaching $100 million, including investments from Airbus, General Electric, American Airlines, JetBlue and Toyota. The company is headquartered just up the road from SpaceX in Hawthorne, California, with an engineering facility in Toulouse, France.
Universal Hydrogen will now conduct further tests at Moses Lake. The company will work on additional software development, and eventually convert the plane to use liquid hydrogen. Early next year, the aircraft will likely be retired — with the fuel cell heading to the Smithsonian Air and Space Museum in Washington, DC.
Universal Hydrogen hopes to start shipping fuel cell conversion kits for regional aircraft like the Dash-8 as soon as 2025. The company already has nearly 250 retrofit orders valued at more than $1 billion from 16 customers, including Air New Zealand. John Thomas, CEO of Connect Airlines, which plans to be the first U.S. carrier to use Universal Hydrogen’s technology, said the “partnership provides the fastest path to zero-emissions operation for the global airline industry.”
Universal Hydrogen isn’t just producing the razors — it’s also selling the blades.
Almost all the hydrogen used today is produced at the point of consumption. That’s not only because hydrogen leaks easily and can damage traditional steel containers, but mainly because in its most useful form — a compact liquid — it has to be kept at just 20 degrees above absolute zero, usually requiring expensive refrigeration.
The liquid hydrogen used in the Moses Lake test came from a commercial “green hydrogen” gas supplier — meaning it was made using renewable energy. Only a tiny fraction of hydrogen produced today is made this way.
If the hydrogen economy is really going to make a dent in the climate crisis, green hydrogen will have to become a lot easier — and cheaper — to produce, store and transport.
Eremenko originally started Universal Hydrogen to design standardized hydrogen modules that could be hauled by standard semi-trucks and simply slotted into aircraft or other vehicles for immediate use. The current design can keep hydrogen liquid for up to 100 hours, and he has often likened them to the convenience of Nespresso units. Universal Hydrogen says it has over $2 billion in fuel service orders for the decade ahead.
Prototype modules were demonstrated in December, and the company hopes to break ground later this year on a 630,000-square-foot manufacturing facility for them in Albuquerque, New Mexico. That nearly $400 million project is contingent on the success of a previously unreported $200+ million U.S. Department of Energy loan application. Eremenko says the application has passed the first phase of due diligence within the DOE.

Some experts are skeptical that hydrogen will ever make a meaningful dent in aviation’s emissions. Bernard van Dijk, an aviation scientist at the Hydrogen Science Coalition, appreciates the simplicity of Universal Hydrogen’s modules, but notes that even NASA has trouble controlling hydrogen leaks with its rockets. “You still have to connect the canisters to the aircraft. How is that all going to be safe? Because if it leaks and somebody lights a match, that is a recipe for disaster,” he says. “I think they’re also underestimating the whole certification process for a new hydrogen powertrain.”
Even when those obstacles are overcome, there is the problem of making enough green hydrogen using renewable electricity, at a price people will be prepared to play. “If you want to get all European flights on hydrogen, you’d need 89,000 large wind turbines to produce enough hydrogen,” says van Dijk. “They would cover an area about twice the size of the Netherlands.”
But Eremenko remains convinced that Universal Hydrogen and its partners can make it work, with the help of a $3 per kilogram subsidy for green hydrogen in Biden’s Inflation Reduction Act. “Of all the things that keep me awake at night,” he says, “the cost and availability of green hydrogens is not one of them.”

The US Defense Department has released a selfie taken in the cockpit of a U-2 spy plane, as an airman flew above the Chinese surveillance balloon that was shot down by the US military earlier this month.
The selfie, taken by the pilot of the U-2, shows the shadow of the aircraft on the balloon and a clear image of the balloon’s payload as it crossed across the continental United States. CNN first reported the existence of the selfie.
The balloon was first spotted by the US on January 28 and ultimately shot down by the US military off the coast of South Carolina after crossing the country.

A senior State Department official said earlier this month that fly-bys “revealed that the high-altitude balloon was capable of conducting signals intelligence collection operations.”
Officials said they’d decided against shooting the balloon down over the US because of its size, fearing falling debris could hurt civilians or property on the ground. Gen. Glen VanHerck, commander of US Northern Command and North American Aerospace Defense Command (NORAD), later said the balloon was 200 feet tall with a payload that weighed a couple of thousand pounds.
Officials also maintained that the balloon was not capable of conducting significant intelligence collection, in part because the US took steps to protect against it immediately upon spotting it.
The U-2 is a single-seat, high-altitude reconnaissance and surveillance aircraft with “glider-like characteristics,” according to the Air Force. Because the planes are regularly “flown at altitudes over 70,000 feet,” pilots “must wear a full pressure suit similar to those worn by astronauts.”

The photo released on Wednesday clearly shows the pilot flying above the balloon, which was hovering 60,000 feet when it was spotted over Montana.
The selfie was captured a week after the balloon entered US airspace near Alaska, and NORAD sent up fighter jets to make a positive identification, according to defense officials.
Still, officials tracking the balloon saw little reason to be alarmed. At the time, according to US officials, the balloon was expected to sail over Alaska and continue on a northern trajectory that intelligence and military officials could track and study.
Instead, shortly after the balloon crossed over land, it alarmed officials by making its unexpected turn south.
Once it was over US territory, officials have argued that the benefits of gathering additional intelligence on the balloon far outweighed the risk of shooting it down over land.
The US sent up U-2 spy planes to track the balloon’s progress, according to US officials.
Recovery efforts began immediately after the balloon was shot down over the Atlantic Ocean on February 4, and were concluded on February 17. Pieces of the debris were transferred to the Federal Bureau of Investigation Laboratory in Virginia to be studied further.
Deputy Pentagon press secretary Sabrina Singh said Wednesday that the payload of the balloon had been recovered.