Category Archives: Commercial aviation

Lockheed Martin Passes Its Mantle for Hybrid Airship Development and Commercialization to AT2

Peter Lobner, 10 May 2023

1. Introduction

On 9 May 2023, Lockheed Martin announced that its hybrid airship business, including intellectual property and related assets, had been transitioned to a newly formed, commercial company called ATAerospace. The Lockheed Martin press release reported, “AT2 Aerospace, based in Santa Clarita, California, is extending our work to bring hybrid airships to fruition. The AT2 team is developing airship solutions to support commercial and humanitarian applications around the world.  Dr. Robert Boyd, retired Lockheed Martin Hybrid Airship program manager, is president and chief operating officer of AT2 Aerospace.”

The AT2 website is here: 

2. Background on Lockheed Martin’s hybrid airship program

Since the 1980s, Lockheed Martin has been developing several different design approaches for semi-buoyant, hybrid airships with lifting body hulls. That work became focused in Lockheed Martin’s Advanced Development Programs (the Skunk Works) in Palmdale, CA, and produced an extensive series of patents related to large, hybrid airship design.

The only Lockheed Martin hybrid airship to fly was the P-791, which was a 120 foot (36.6 meter) long, tri-lobe, semi-buoyant hybrid airship that flew under a Defense Advanced Research Projects Agency (DARPA) sponsored Project WALRUS Phase 1 contract, and also served as a sub-scale technology demonstrator for future Lockheed Martin heavy-lift hybrid airships. The first flight of the P-791 took place on 31 January 2006 at Lockheed Martin’s facility in Palmdale.  Airship magazine reported that the P-791 flew six times. Lockheed Martin claimed that all flight test objectives were successfully met and there were no subsequent flight tests.

Lockheed Martin P-791. Source: Lockheed Martin (2006)

In March 2011, Lockheed Martin announced that it planned to develop a larger commercial version of the P-791, to be called SkyTug, which would be a scaled up hybrid airship designed to carry at least 20 tons of cargo.  A trademark application for the term “SkyTug” was filed on 25 August 2011.

By 2013, reference to SkyTug had disappeared and Lockheed Martin was promoting the LMH-1 as their next large commercial hybrid airship based on the P-791 design.  

General arrangement of the LMH-1 hybrid airship.  Source:  Lockheed Martin

Rendering, LMH-1 bow quarter view. Source: Lockheed Martin via BBC (November 2019)

On March 12, 2012 the U.S. Federal Aviation Administration (FAA) announced that Lockheed Martin Aeronautics submitted an application for type certification for the model LMZ1M (LMH-1), which is “a manned cargo lifting hybrid airship incorporating a number of advanced features.”  The FAA assigned docket number FAA-2013-0550 to that application. 

To address the gap in airship regulations head-on, Lockheed Martin submitted to the FAA their recommended criteria document, “Hybrid Certification Criteria (HCC) for Transport Category Hybrid Airships,” which is a 206 page document developed specifically for the LMZ1M (LMH-1).  The HCC is also known as Lockheed Martin Aeronautics Company Document Number 1008D0122, Rev. C, dated 31 January 2013.  You can download the HCC document and related public docketed items from the FAA website here:

In November 2015, the FAA’s Seattle Aircraft Certification Office approved Lockheed’s project-specific certification plan for the LMZ1M (LMH-1). In a 17 November 2015 press release, Lockheed Martin announced:

“Given that Hybrid Airships did not fit within existing FAA regulations, the team worked to create a new set of criteria allowing non rigid hybrid airships to safely operate in a commercial capacity. Transport Canada was also involved in the development of this criteria to ensure it included safety concerns unique to Canada.”

“Lockheed Martin and the FAA have been working together for more than a decade to define the criteria to certify Hybrid Airships for the Transport Category. This criteria was approved by the FAA in April 2013.  Following that approval, the team has been developing the project specific certification plan over the past two years, which details how it will accomplish everything outlined in the Hybrid Certification Criteria.”

“Earlier this year Lockheed Martin along with Hybrid Enterprises LLC kicked off sales for the 20 ton variety of the Hybrid Airship. They are on track to deliver operational airships as early as 2018.”

No new documentation was subsequently added to the public webpage for docket FAA-2013-0550, so there was no public visibility of the type certification effort.  

In September 2017, Lockheed Martin reported it had Letters of Intent (LOIs) for 24 LMH-1 hybrid airships, with their largest customer being Straightline Aviation (, which had signed an LOI for 12 LMH-1s. At that time, the first “float out” of the LMZ1M (LMH-1) had slipped to 2019. As of May 2023, the airship has not yet been “floated out”. 

On 9 May 2023, Lockheed Martin reported, “For some time, we have been in search of a transition partner to continue development of this important commercial work.” That “transition partner” is the newly formed, commercial company ATAerospace.

3. The AT2 Aerospace Z1 Hybrid Airship

As portrayed on the AT2 Aerospace website, their Z1 hybrid airship appears to be the current incarnation of the former Lockheed Martin LMH-1. AT2 Aerospace summarizes the main attributes of their Z1 hybrid airship as follows:

“AT2 Aerospace’s revolutionary hybrid airship is the future of aviation technology. Capable of operating in the most remote and inaccessible locations, this innovative aircraft offers a cost-effective solution for heavy cargo transpiration while minimizing environmental and social impact.”

  • “The Z1’s unique Air Cushion Landing System (ACLS) allows the Z1 to land and takeoff from almost any location on the planet.
  • The Z1 utilizes buoyant lift technology delivering exceptional fuel efficiency, minimizing carbon emissions, and ultimately reducing transportation costs.
  • The Z1 will connect emerging economies to global trade networks.
  • The Z1 moves cargo faster than sea and land transportation at a fraction of the cost of existing cargo aircraft, filling a major gap in the global transportation market from a speed vs. cost perspective.”

AT2 Aerospace also identified the following attributes:

  • Simple controls minimize human error
  • Large volume cargo bays, larger payloads
  • Safer in icing effects
  • Quiet: Ideal for noise sensitive locations

AT2 Aerospace expects that their Z1 hybrid airship will “open the entire world to commerce, humanitarian aid and exploration with affordable and reliable operations.”

General arrangement of the Z1 hybrid airship. Source: AT2 Aerospace

The near-term challenge for AT2 Aerospace will be to get clarity from the FAA on the actions remaining, and the approximate time scale, to conclude the first-ever type certification process for a hybrid airship in the U.S. With a type certificate in hand, the Z1 can be put to the test by a few early-adopters in what hopefully will become an emerging worldwide commercial airship market.

4. For more information

Airbus Delivers its 10,000th Aircraft

Peter Lobner

Airbus was founded on 18 December 1970 and delivered its first aircraft, an A300B2, to Air France on 10 May 1974. This was the world’s first twin-engine, wide body (two aisles) commercial airliner, beating Boeing’s 767, which was not introduced into commercial service until September 1982. The A300 was followed in the early 1980s by a shorter derivative, the A310, and then, later that decade, by the single-aisle A320. The A320 competed directly with the single-aisle Boeing 737 and developed into a very successful family of single-aisle commercial airliners: A318, A319, A320 and A321.

On 14 October 2016, Airbus announced the delivery of its 10,000th aircraft, which was an A350-900 destined for service with Singapore Airlines.

EVE-1236Source: Airbus

In their announcement, Airbus noted:

“The 10,000th Airbus delivery comes as the manufacturer achieves its highest level of production ever and is on track to deliver at least 650 aircraft this year from its extensive product line. These range from 100 to over 600 seats and efficiently meet every airline requirement, from high frequency short haul operations to the world’s longest intercontinental flights.”

You can read the complete Airbus press release at the following link:

As noted previously, Airbus beat Boeing to the market for twinjet, wide-body commercial airliners, which are the dominant airliner type on international and high-density routes today. Airbus also was an early adopter of fly-by-wire flight controls and a “glass cockpit”, which they first introduced in the A320 family.

In October 2007, the ultra-large A380 entered service, taking the honors from the venerable Boeing 747 as the largest commercial airliner.   Rather than compete head-to-head with the A380, Boeing opted for stretching its 777 and developing a smaller, more advanced and more efficient, all-composite new airliner, the 787, which was introduced in airline service 2011.

Airbus countered with the A350 XWB in 2013. This is the first Airbus with fuselage and wing structures made primarily of carbon fiber composite material, similar to the Boeing 787.

The current Airbus product line comprises a total of 16 models in four aircraft families: A320 (single aisle), A330 (two aisle wide body), A350 XWB (two aisle wide body) and A380 (twin deck, two aisle wide body). The following table summarizes Airbus commercial jet orders, deliveries and operational status as of 30 November 2016.

Airbus orders* Includes all models in this family. Source:

Boeing is the primary competitor to Airbus. Boeing’s first commercial jet airliner, the 707, began commercial service Pan American World Airways on 26 October 1958. The current Boeing product line comprises five airplane families: 737 (single-aisle), 747 (twin deck, two aisle wide body), 767 (wide body, freighter only), 777 (two aisle wide body) and 787 (two aisle wide body).

The following table summarizes Boeing’s commercial jet orders, deliveries and operational status as of 30 June 2016. In that table, note that the Boeing 717 started life in 1965 as the Douglas DC-9, which in 1980 became the McDonnell-Douglas MD-80 (series) / MD-90 (series) before Boeing acquired McDonnell-Douglas in 1997. Then the latest version, the MD-95, became the Boeing 717.

Boeing commercial order status 30Jun2016


Boeing’s official sales projections for 2016 are for 740 – 745 aircraft. Industry reports suggest a lower sales total is more likely because of weak worldwide sales of wide body aircraft.

Not including the earliest Boeing models (707, 720, 727) or the Douglas DC-9 derived 717, here’s how the modern competition stacks up between Airbus and Boeing.

Single-aisle twinjet:

  • 12,805 Airbus A320 family (A318, A319, A320 and A321)
  • 14,527 Boeing 737 and 757

Two-aisle twinjet:

  • 3,260 Airbus A300, A310, A330 and A350
  • 3,912 Boeing 767, 777 and 787

Twin aisle four jet heavy:

  • 696 Airbus A340 and A380
  • 1,543 Boeing 747

These simple metrics show how close the competition is between Airbus and Boeing. It will be interesting to see how these large airframe manufacturers fare in the next decade as they face more international competition, primarily at the lower end of their product range: the single-aisle twinjets. Former regional jet manufacturers Bombardier (Canada) and Embraer (Brazil) are now offering larger aircraft that can compete effectively in some markets. For example, the new Bombardier C Series is optimized for the 100 – 150 market segment. The Embraer E170/175/190/195 families offer capacities from 70 to 124 seats, and range up to 3,943 km (2,450 miles).  Other new manufacturers soon will be entering this market segment, including Russia’s Sukhoi Superjet 100 with about 108 seats, the Chinese Comac C919 with up to 168 seats, and Japan’s Mitsubishi Regional Jet with 70 – 80 seats.

At the upper end of the market, demand for four jet heavy aircraft is dwindling. Boeing is reducing the production rate of its 747-8, and some airlines are planning to not renew their leases on A380s currently in operation.

It will be interesting to watch how Airbus and Boeing respond to this increasing competition and to increasing pressure for controlling aircraft engine emissions after the Paris Agreement became effective in November 2016.

Status of Ukraine’s Giant Transport Aircraft: Antonov An-124 and An-225

Peter Lobner, updated 26 September 2023

Historically, the Antonov Design Bureau was responsible for the design and development of large military and civil transport aircraft for the former Soviet Union. With headquarters and production facilities in and around Kiev, this Ukrainian aircraft manufacturing and servicing firm is now known as Antonov State Company. The largest of the jet powered transport aircraft built by Antonov are the four-engine An-124 and the even larger six-engine An-225.

An-124 Ruslan (NATO name: Condor)

The An-124 made its first flight in December 1982 and entered operational service in 1986. This aircraft is a counterpart to the Lockheed C-5A, which is the largest U.S. military transport aircraft. A comparison of the basic parameters of these two aircraft is presented in the following table.

An-124 vs C-5A_Aviatorjoedotnet


As you can see in this comparison, the An-124 is somewhat larger than the C-5A, which has a longer range, but at a slower maximum speed.

The An-124 currently is operated by the Russian air force and also by two commercial cargo carriers: Ukraine’s Antonov Airlines and Russia’s Volga-Dnepr Airlines. The civil An-124-100 is a commercial derivative of the military An-124. The civil version was certified in 1992, and meets all current civil standards for noise limits and avionic systems.

In their commercial cargo role, these aircraft specialize in carrying outsized and/or very heavy cargo that cannot be carried by other aircraft. These heavy-lift aircraft serve civil and military customers worldwide, including NATO and the U.S. military. I’ve seen an An-124s twice on the tarmac at North Island Naval Station in San Diego. In both cases, it arrived in the afternoon and was gone before sunrise the next day. Loading and/or unloading occurred after dark.


An-124-100. Source: Wikimedia Commons

As shown in the following photo, the An-124 can retract its nose landing gear and “kneel” to facilitate cargo loading through the raised forward door.

An-124_ramp down

An-124-100. Source: Mike Young / Wikimedia Commons

The following diagram shows the geometry and large size of the cargo hold on the An-124. The built-in cargo handling equipment includes an overhead crane system capable of lifting and moving loads up to 30 metric tons (about 66,100 pounds) within the cargo hold. As shown in the diagram below, the cargo hold is about 36.5 meters (119.7 feet) long, 6.4 meters (21 feet) wide, and the clearance from the floor to the ceiling of the cargo hold is 4.4 meters (14.4 feet). The installed crane hoists may reduce overhead clearance to 3.51 meters (11.5 feet).


An-124-100 cargo hold dimensions. Source:


An-124-100. Source:

Production of the An-124 was suspended following the Russian annexation of Crimea in 2014 and the ongoing tensions between Russia and Ukraine. In spite of repeated attempts by Ukraine to restart the An-124 production line, it appears that Antonov may not have the resources to restart An-124 production. 

An-225 Mriya

The An-225 was adapted from the An-124 and significantly enlarged to serve as the carrier aircraft for the Soviet space shuttle, the Buran. The relative sizes of the An-124 and An-225 are shown in the following diagram, with a more detailed comparison in the following table.

An-124 & 225 planform comparison

An-124 & -225 comparison. Source:

An-124 & 225 comparison

An-124 & -225 comparison. Source:

The only An-225 ever produced made its first flight in December 1988. It is shown carrying the Buran space shuttle in the following photo.

AN-225 & Buran

An-225 carrying Buran space shuttle. Source:

After the collapse of the Soviet Union in 1991 and the cancellation of the Buran space program, the An-225 was mothballed for eight years until Antonov Airlines reactivated the aircraft for use as a commercial heavy-lift transport. In this role, it can carry ultra-heavy / oversize cargo weighing up to 250 metric tons (551,000 pounds).

An-225 gear down

An-225 Mriya. Source: AntonovAn-225 gear up

In 2016, it appeared that the giant An-225 was about to enter series production after Antonov and Aerospace Industry Corporation of China (AICC) signed a deal on 30 August 2016 for An-225 production in China. At the time, it was expected that the first new An-225 could be produced in China as early as in 2019. A Chinese An-225 would modernize and greatly expand China’s military and civil airlift capabilities.  While it isn’t clear how that airlift capability would be employed, it certainly will improve China’s ability to deliver heavy machinery, bulk material, and many personnel anywhere in the world, including any location in and around the South China Sea that has an adequate runway.  

26 September 2023 update

In late February 2022, the An-225 was destroyed by invading Russian forces at the Hostomel Airport near Kyiv, where the giant aircraft was undergoing regular maintenance intended to support its continued operational use into the 2030s. 

Source: Oleksii Samsonov / KCSA via The Moscow Times

Source: Oleksii Samsonov via Aero Times

A second unfinished airframe of the An-225, originally intended for ground testing, still exists at an unspecified location.  That second airframe, plus serviceable parts salvaged from the original An-225, would form a starting point for building another flyable AN-225.

Time will tell if an An-225 can be rebuilt.  I hope we’ll see Mriya fly again.

For more information


Modern Airships

This August 2016 post, which included links to 14 articles on specific historic and modern  airships, was replaced in August 2019.

“Modern Airships” now is a three-part post that contains an overview of modern airship technology in Part 1 and links in Parts 1, 2 and 3 to more than 275 individual articles on historic and advanced airship designs. Here are the links to all three parts:

I hope you’ll find the expanded Modern Airships series of posts to be informative, useful, and different from any other single source of information on this subject.

Best regards,

Peter Lobner

August 2019

How Long Does it Take to Certify a Commercial Airliner?

Peter Lobner

After designing, developing, and manufacturing a new commercial airliner, I’m sure the airframe manufacturer has a big celebration on the occasion of the first flight. The ensuing flight test and ground static test programs are intended to validate the design, operating envelope, and maintenance practices and satisfy these and other requirements of the national certifying body, which in the U.S. is the Federal Aviation Administration (FAA). Meanwhile, airlines that have ordered the new aircraft are planning for its timely delivery and introduction into scheduled revenue service.

The time between first flight and first delivery of a new commercial airliner is not a set period of time. As you can see in the following chart, which was prepared by Brian Bostick (, there is great variability in the time it takes to get an airliner certified and delivered.

Time to certify an airliner

In this chart, the Douglas DC-9 has the record for the shortest certification period (205 days) with certification in November 1965. The technologically advanced supersonic Concorde had one of the longest certification periods (almost 2,500 days), with authorization in February 1976 to conduct a 16-month demonstration period with flights between Europe and the U.S. before starting regular commercial service.

The record for the longest certification period goes to the Chinese Comac ARJ21 twin-jet airliner, which is the first indigenous airliner produced in China. The first ARJ21 was delivered to a Chinese airline in November 2015. The ARJ is based on the DC-9 and reuses tooling provided by McDonnell Douglas for the licensed production of the MD-80 (a DC-9 variant) in China. I suspect that the very long certification period is a measure of the difficulty in establishing the complete aeronautical infrastructure needed to deliver an indigenous commercial airliner with an indigenous jet engine.

In the chart, compare the certification times for the following similar commercial airliners:

  • Four-engine, single aisle, long-range airliners: Boeing 707 (shortest), Douglas DC-8, Convair CV-880, Vickers VC-10, De Havilland Comet (longest)
  • Three-engine, single aisle, medium range airliners: Boeing 727 (shorter), Hawker Siddeley Trident (longer)
  • Two-engine, single aisle airliners: Douglas DC-9 (shortest), Boeing 737, Boeing 757, Airbus A320, British Aircraft Corporation BAC 1-11, Dassault Mercure, Caravelle (longest)
  • Two-engine, single aisle, short range regional jets: Embraer ERJ 145 (shortest), Bombardier CRJ-100, BAe 146, Fokker F-28, ERJ 170, Bombardier CS Series, Mitsubishi MRJ, Sukhoi Superjet, VFW-614, Comac ARJ21 (longest)
  • Four-engine, wide-body, long-range airliners: Boeing 747, Airbus A340, Airbus A380 (longest)
  • Three-engine, wide-body, long-range airliners: Douglas DC-10 (shorter), Lockheed L-1011 (longer)
  • Two-engine, wide-body airliners: Boeing 767 (shortest), Boeing 777, Airbus 350, Airbus A300, Boeing 787 (longest)

Time is money, so there is tremendous economic value in minimizing the time between first flight and first delivery. The first 16 aircraft at the top of the chart all enjoyed relatively short certification periods. This group, which includes many aircraft that appeared in the 1960s – 70, averaged about 400 days between first flight and first delivery.

More modern aircraft (blue bars in the chart representing aircraft appearing in 2000 or later) have been averaging about 800 days between first flight and first delivery (excluding ARJ21).