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How Airbus fought its own pitch battle

Airbus has not been immune to the consequences of spurious air data, and unexpected incidents illustrate the difficulties designers and regulators face in predicting and avoiding unintended aircraft behaviour.

Grounding of the Boeing 737 Max followed two fatal accidents involving unreliable angle-of-attack information and persistent automatic nose-down response from the pitch-control system.

Airbus types have experienced serious issues which appear superficially similar to those affecting the Max. But some crucial considerations, centred on the Airbus design and time in service, have resulted in far less disruptive regulatory intervention.

Shortly after an Eva Air A330’s departure in 2012 it suffered an angle-of-attack sensor jam, at 5°, as it climbed through 11,000ft. Although the angle was shallow, angle-of-attack margins become narrower, increasing the risk of stall, as an aircraft climbs and its Mach number increases.

When the A330 reached an altitude at which this false angle-of-attack data exceeded a critical threshold, the aircraft’s stall-protection mechanism responded by automatically commanding nose-down.

Investigation of the incident revealed that not only could the flight-control laws command a nose-down pitch, but pilots might not be able to counter the attitude – even if they pulled fully back on the sidestick.

The incident spurred an emergency change of procedures, instructing crews to turn off air data reference instruments if symptoms of a sensor jam emerged, or if the aircraft entered an “unmanageable pitch-down attitude” despite full-aft sidestick inputs.

Analysis of the A330 incident pointed to the possibility that conic plates on which the angle-of-attack sensors were mounted had contributed to icing and a subsequent blockage.

Jamming of two or three sensors at the same angle could cause the stall-protection system to activate, investigators stated.

Operators were instructed, in early 2013, to replace the conic plates with a flat-plate mounting for the sensors.

But a similar incident, in November 2014, involving a Lufthansa Airbus A321 climbing out of Bilbao underscored the difficulties in anticipating misbehaviour.

Two of the A321’s angle-of-attack sensors froze at a position of 4.5° as the jet passed 19,500ft. It continued to climb but, as it reached 31,000ft, the crew observed airspeed discrepancies and switched off the autopilot, bringing the aircraft under manual control.

The A321 abruptly pitched 3.5° nose-down because, at the speed of M0.675, the jammed sensors were incorrectly showing an angle-of-attack greater than the 4.2° threshold for the stall-protection system.

With two of the three angle-of-attack sensors jammed at a consistent, albeit wrong, position the A321’s air data reference system eliminated the apparently spurious readings from the third sensor. As a result the elevator aileron computer – which controls pitch through the elevators and horizontal stabiliser – took into account only the two incorrect sensors.

The aircraft entered a 4,000ft/min descent and the captain was only able to restore and maintain level flight by pulling fully back on the sidestick. Manual nose-up trim was unavailable. Control was eventually regained through measures which led the aircraft to revert to alternate flight law, disengaging the stall-protection system.

Investigators discovered, in the wake of the incident, that the A321 was not fitted with the conic sensor plates suspected in the A330 event, but conventional flat plates. Water ingestion was considered a contributor.

Airbus and the European Union Aviation Safety Agency warned A330 and A320-family crews that, if Mach number continued to increase during a nose-down command, the angle-of-attack threshold for activating stall-protection would continue to decline – resulting in further nose-down orders from the flight-control system.

Pilots were issued with new emergency procedures which instructed them to turn off two of the three air data reference units, forcing the reversion to alternate flight law, if they observed symptoms of jammed angle-of-attack sensors.

There are crucial differences between the events that occurred on the Airbus jets and those preceding the 737 Max accidents, argues EASA.

“While the Airbus events were caused by multiple failures of the angle-of-attack system, the 737 Max issue seems to be caused by just one only faulty sensor, thus presenting a higher probability risk,” it says.

“The crew of the Airbus aircraft were able to recover control of the aircraft by switching to an alternate flight-control mode and the aircraft landed in a normal way.”

EASA points out that, although the 737 has evolved over five decades, the 737 Max is “still a young aircraft model” with relatively time since service entry in 2017.

“Before these [Airbus] events occurred, the Airbus aircraft models had accumulated a significant number of flight hours without any such issue, allowing certification authorities to perform a comprehensive and robust continued airworthiness review,” it adds.

Simultaneous jamming of two angle-of-attack sensors, and the rejection of a valid third, had previously led to the fatal crash of an A320 during a check flight at Perpignan in November 2008.

Water ingested by the sensors, left unprotected during routine washing, froze as the aircraft cruised at 32,000ft. The sensors jammed at low angle-of-attack settings – respectively 4.2° and 3.8° – and maintained these readings as the crew conducted the descent.

As a result the sensors were rendered inoperative and failed to detect the A320’s increasing angle-of-attack when, as part of the check flight, the crew deliberately reduced airspeed at low altitude to test the stall-protection system. The aircraft slowed and the horizontal stabiliser trimmed nose-up but the protection system did not activate.

“The crew waited for the triggering of these protections while allowing the speed to fall to that of a stall,” the inquiry by French investigation authority BEA found.

When the aircraft stalled, the crew increased thrust, and the stabiliser’s nose-up position caused the A320 to pitch up. The crew failed to recover from the stall, which occurred at about 3,000ft; the jet lost height and crashed into the Mediterranean Sea.

EASA describes the high-incidence protection system on the A320 and A330 families as “robust”, noting the inclusion of three angle-of-attack sensors compared with two on the 737 Max, normally enabling voting logic to eliminate a single erroneous reading. It adds that the Airbus has “enhanced” monitoring and surveillance of the sensors.

“Safety risk assessments are performed using a methodical approach that accounts for the severity of the potential consequence, the available mitigations – such as crew procedures – and the probability of the root cause to [occur or recur].”

All these considerations, it says, resulted in the differences in regulatory reaction and mandatory actions in the Airbus and Boeing cases.

Seven weeks before the Perpignan crash an upset involving an A330 in cruise exposed the virtual impossibility of certification testing every possible scenario involving flight-control response to corrupted air data.

The Qantas aircraft, operating at 37,000ft, experienced a sudden failure mode in one of the three air data inertial reference units, which started transmitting invalid and frequent spikes in angle-of-attack information.

While the data was invalid the system did not flag it as such. The aircraft’s flight-control primary computer abruptly pitched the aircraft 8.4° nose-down, throwing almost all the unrestrained occupants to the ceiling. Over a third of the 315 people on board sustained injuries.

The precise mechanism for the data spikes could not be determined, and the Australian Transport Safety Bureau attributed the event to a “single, rare type of trigger” combined with a “marginal susceptibility” within the air data unit’s central processor. Just three occurrences of similar data-spiking had occurred in 128 million hours of operation with the Northrop Grumman units, two of which involved the one fitted in the Qantas aircraft.

Analysis determined that the occurrence was the only known instance in which the design limitation had led to a pitch-down command in over 28 million flight hours on A330s and A340s – a rate which complied with the criteria for events classified as ‘hazardous’ but not ‘catastrophic’.

Investigators pointed out that the flight computer’s algorithm’s were “generally very effective” and could handle “almost all possible situations” involving incorrect angle-of-attack data, adding that the design limitation was “very unlikely” to have led to a more adverse outcome.

Development of the A330 flight-control system involved “many elements to minimise the risk of a design error”, including peer review, a system safety assessment, testing and simulation, none of which identified the limitation in the algorithm.

“Due to the wide range of potential inputs into a complex system…simulation and testing programs cannot exhaustively examine all the possible patterns of inputs,” says the inquiry, stating that the testing activities for the flight-control computer “would not realistically” have included the multiple data-spike scenario.

Airbus nevertheless redesigned the angle-of-attack algorithm to prevent a recurrence of the Qantas incident, and improved the flight-control computer to enhance its ability to detect multiple angle-of-attack sensor blockage.

The A330 and A321 blockage incidents led EASA to order removal of specific angle-of-attack sensors and their replacement with less susceptibility to adverse environmental conditions.

Airbus also developed upgrades to the elevator and aileron computers, introducing improved sensor monitoring for the A320 family and later incorporating “flight control aspects” for the A320neo family, says EASA.

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Red Wings A321 sports revamped livery

Russian carrier Red Wings has taken delivery of an Airbus A321 featuring a revamped livery for the airline.

The 220-seat aircraft (VP-BER), with an all-economy layout, arrived at Moscow Domodedovo on 18 April following painting in Montpellier.

Red Wings says the A321, a 2006 airframe, is one of four which will be introduced this year to modernise the carrier’s fleet.

“The new corporate identity is a reflection of our internal changes,” says Evgeny Klyucharyov, highlighting on-board service improvements and adjustments to increase business efficiency.

Russian bureau Duck Design has produced the revised livery, which features a red logo, resembling a simplified pair of wings, which is replicated in white with the carrier’s name on a red vertical fin.

Red Wings says the logo is a “logical continuation” of the previous one, but more “modern and dynamic”.

Partner operator Nordavia has also recently undergone a rebrand, under the Smartavia name, featuring a new livery.

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Red Wings/Vyacheslav Klychkov

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SpiceJet to lease six more 737-800s

Indian budget carrier SpiceJet has agreed to lease six more Boeing 737-800s that are expected to join its fleet within the next two weeks.

The airline says that it has applied to the Directorate General of Civil Aviation for no-objection certificates that will allow it to import the aircraft.

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In addition to earlier plans to lease 16 other 737NGs and induct five Bombardier Q400s by June, SpiceJet will take delivery of 27 aircraft in the near term.

Those aircraft will help it to ramp up services and cover the capacity lost from the shutdown of rival carrier Jet Airways.

“SpiceJet continues to work closely with the government and regulatory authorities to help minimise passenger inconvenience,” says chairman and managing director Ajay Singh. “We will induct as many as 27 planes in a record time of less than two weeks and are hopeful that these inductions will help considerably ease the pressure situation.”

Jet Airways suspended operations on 17 April after it failed to secure emergency funding from its banks to pay for fuel and other critical services.

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Civil aircraft feature on EU’s US countermeasures list

European regulators have listed large civil aircraft and helicopters among potential targets of trade countermeasures aimed at US exports, following the US government’s plans to introduce tariffs on Airbus jets.

The European Commission has opened a consultation on the measures, publishing an 11-page preliminary list of products which could fall under the new regime, featuring increased customs duties of up to 100%.

It includes aircraft with an unladen weight above 15t as well as helicopters both above and below 2t.

“The proposed action will only apply to new non-military aircraft,” the Commission has clarified in the list.

It has invited public consultation on the proposal which will run until 31 May. The provisional list amounts to some $20 billion of US exports to the European Union.

The Commission is responding to proposed US government tariffs on a range of products put forward in the context of a long-running transatlantic dispute over subsidies for large civil aircraft programmes.

Both sides have maintained that their major commercial airframers, Airbus and Boeing, have benefited from government assistance in various forms, and both have claimed to have obtained the upper hand in dispute-resolution cases at the World Trade Organisation.

The Commission insists that a final compliance report, adopted by the WTO in April, shows US subsidies to Boeing “continue to cause significant harm” – including lost sales – to Airbus.

“We must continue to defend a level playing field for our industry,” says European trade commissioner Cecilia Malmstrom. “But let me be clear, we do not want a tit-for-tat.

“While we need to be ready with countermeasures, in case there is no other way out, I still believe that dialogue is what should prevail between important partners.”

The WTO would have the final decision on a suitable level of redress, enabling a final list of products to be drawn up for inclusion.

Under the consultation the Commission says it expects to receive input from private stakeholders potentially affected by the planned European countermeasures.

“The information gathering should provide the Commission with input to assist it in assessing the parameters of planned commercial policy measures,” it adds, enabling it to “be in a position to promptly take action”.

Alongside the aerospace component the preliminary list includes – among multiple other products – tractors and excavators, suitcases, handbags, wine, chocolate, fish and seafood, bicycle parts, and playing cards.

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Air Mauritius takes delivery of first A330neo

Air Mauritius has received its first Airbus A330-900 at a ceremony in Toulouse.

The carrier will become both the first in the southern hemisphere to operate the A330neo and the first worldwide to operate it alongside the A350, notes Airbus.

It adds that the first Air Mauritius A330-900 has been given the name Aapravasi Ghat, referencing a UNESCO World Heritage Centre located in the Indian Ocean island nation.

Air Mauritius chief executive Somas Appavou hails the jet as “another milestone in our fleet modernisation programme”. The airline has another A330-900 on order, and Appavou expects the Rolls-Royce Trent 7000-powered aircraft to “bring more flexibility and efficiency to our operations while supporting our network strategy”.

He likens the A330neo’s comfort levels to those of the A350, of which Air Mauritius has two in service and four on order, Cirium’s Fleets Analyzer shows. “With the addition of the A330neo to our fleet, Air Mauritius will further reinforce its focus and emphasis on the customer who are at the very core of our business model,” states Appavou.

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The aircraft in Toulouse on 18 April 2019


Air Mauritius’s A330neo will have a two-class cabin, with 28 seats in business and 260 in economy, Airbus notes, adding that the aircraft will be deployed on routes connecting Mauritius to Europe (mainly London and Geneva), India, and Southeast Asian destinations, and to regional points including Johannesburg in South Africa, Madagascan capital Antananarivo, and French island Reunion.

In addition to its two A350-900s, Air Mauritius has three A340-300s, two A330-200s and two A319s.

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Washington National set to open first piece of $1bn expansion

American Airlines will begin using the first part of what will become a new regional concourse at Ronald Reagan Washington National airport later this month.

The first section of aircraft apron – the pavement that will one day serve the new concourse’s northern side – with up to 12 regional aircraft parking positions is due to open during the week of 22 April, airport operator the Metropolitan Washington Airports Authority (MWAA) says. The ramp includes space for overnight aircraft parking.

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Edward Russell

“We’re moving very fast,” says Greg Trojan, project environmental health and safety manager at Turner Construction, on a tour of the new ramp for FlightGlobal. Turner is contracted to build the new concourse.

The concourse is part of the larger $1 billion Project Journey works that also include new security checkpoints. When complete, all four concourses – the existing three plus the one under construction – in terminal B/C at Washington National will be connected inside security.

The new apron and aircraft parking positions replace existing ones where work on the new concourse moves to next, says Trojan. The steel structure of the facility will begin rising in “about a month”, he adds.

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Edward Russell

The concourse is on schedule to open by July 2021, while the security checkpoints are a few months behind schedule due to inclement weather and are expected to open by February 2021, MWAA executives said at the operator’s monthly boarding meeting on 17 April.

The security works, also known as the secure National Hall project, were scheduled to open in late 2020.

American, which operates a hub at Washington National, plans to take full advantage of Project Journey when work is complete. The Fort Worth, Texas-based carrier will shift flights operated by 50-seat regional jets to larger ones with up to 76 seats when the 14-gate concourse opens.

“American Airlines is looking forward to our amazing new space at Washington National,” an airline spokesman says. “We are particularly looking forward to the elimination of busing between gate 35X and regional aircraft.”

The bus operation from gate 35X at the airport is widely disliked by Washington DC-area travellers.

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Rendering of the new concourse at Washington National


Vasu Raja, vice-president of network at American, told FlightGlobal in December that the Project Journey works are “critical enablers” of the airline’s growth plans at Washington National. He affirmed plans to upgauge flights to larger aircraft but did not provide additional details.

The carrier is already flying more larger aircraft through Washington National. Seats are up 1.5% on 0.4% fewer flights year-over-year in the first six months of 2019, Cirium schedule data shows.

American is focusing growth at its three most profitable hubs – Dallas/Fort Worth, Charlotte and Washington National – over the next few years. It is adding more than 100 flights at Dallas/Fort Worth this summer under its “DFW 900” initiative, plans to boost Charlotte to roughly 700 flights a day next year, and will begin upgauging fights at National from 2021.

New facilities enable growth at the three airports. The carrier moves into a renovated 15-gate satellite at Dallas/Fort Worth airport in May, adds four more gates at Charlotte by the end of 2019, and will gain the new Project Journey concourse at Washington National in two years.

While not expected to impact American’s plans for Washington National, the on-going grounding of the Boeing 737 Max may limit its growth this year. The airline will report first quarter earnings on 26 April and is expected to provide an update on the impact of the suspension.

American has removed the 737 Max from schedules through August, resulting in the cancellation of up to 115 flights a day.

The airline has previously said it will grow capacity by roughly 3% in 2019.

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Honeywell reports sales gains and downplays effect of 737 issues

US aerospace giant Honeywell has reported strong gains in first quarter 2019 aerospace sales, with executives predicting little impact from Boeing’s reduction of 737 Max production.

“Based on our customer’s current production schedules, we do not expect a significant impact in our 2019 results,” Honeywell chief financial officer Greg Lewis says of Boeing on 18 April.

“We have numerous systems” on the 737 Max, adds chief executive Darius Adamczyk. “But… the impact for us is negligible, certainly for Q2 and given that just about everybody expects a resolution.”

“We do expect that delivery of these planes and the production rates to resume in the second half of this year,” Adamczyk adds.

Seattle-based Boeing reduced 737 Max production in mid-April to 42 aircraft monthly, a 19% cut from the previous 52 aircraft-monthly rate. The company slashed production following the global 737 Max grounding.

In the first quarter, Honeywell’s sales of equipment for new commercial aircraft increased 9% year-on-year to $759 million, while commercial aviation aftermarket sales jumped 7% to $1.4 billion.

Honeywell’s space and aerospace defence sales surged 12% to $1.2 billion.

CFO Lewis attributes gains to increased shipments of products to business jet makers Gulfstream, Dassault Aviation and Textron.

He notes particularly strong demand for avionics used in the cockpits of Dassault F900 and F200 business jets, and for engines used in the Textron Citation Latitude jet. Honeywell makes the Latitude’s auxiliary power unit.

Additionally, the US government’s mandate that aircraft have ADS-B location systems by 2020 drove increased demand for ADS-B equipment, Lewis adds.

Despite those areas of strength, Honeywell’s 2018 divestiture of an engine turbocharger division pushed down its total first quarter aerospace sales 16% in one year, to $3.3 billion. The aerospace unit posted a profit of $838 million in the first quarter, down 6% from the same period last year.

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The leased jets backfilling for lost 737 Max capacity

As operators across the world scramble to fill capacity gaps created by the grounding of the Boeing 737 Max, we present this gallery of aircraft that have been drafted into affected fleets

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Spotter LEVT/Creative Commons

Enter Air has taken two Boeing 737-800s (including OM-GTF from Slovak charter operator Go2Sky, pictured above in 2017) on wet leases since the 737 Max grounding began, Cirium’s Fleets Analyzer shows. The Polish charter carrier had two Max 8s in service on 9 March 2019.

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Victor/Creative Commons

Among the aircraft that Air Italy has taken on lease since the grounding began are an Embraer 190 from Bulgaria Air (LZ-SOF, pictured above) and a Fokker 100 (9A-BTE, pictured below in the livery of Croatian charter operator Trade Air, in 2015), Fleets Analyzer data shows. Air Italy had three Max aircraft in service on 9 March.

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Valentin Hintikka/Creative Commons

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Marvin Mutz/Creative Commons

Royal Air Maroc has taken an Airbus A320 (LY-VEB, pictured above in SunExpress service during 2018) on lease since the grounding began. It had two Max jets in service on 9 March, according to Fleets Analyzer.

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Eric Salard/Creative Commons

Among other initiatives, Air Canada has been speeding the entry into service of four A321s it purchased from now-defunct Wow Air (including TF-MOM, pictured above). The operator had 24 Max aircraft in service on 9 March.

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Ken Fielding/Creative Commons

Among other types, leisure operator TUI Group has brought a number of 737-800s back into its fleet since the grounding began, including several that had been leased to Canadian subsidiary Sunwing Airlines (including G-FDZD, pictured above in an old Thomson Airways livery), Fleets Analyzer shows. It has been “activating spare aircraft within its fleet and extending leases for aircraft which were due for replacement”. TUI had 15 Max aircraft in service on 9 March.

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Alec Wilson/Creative Commons

Polish carrier LOT has leased in four 737 aircraft since the grounding began (including YR-BMK, pictured above in Blue Air livery during 2018). The operator had five Max jets in service on 9 March, according to Fleets Analyzer.

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Riik@mctr/Creative Commons

Icelandair has taken a 767-300ER on lease since the grounding began (CS-TKR, pictured above during 2017 in EuroAtlantic Airways livery), Fleets Analyzer data shows. It is set to take another 767 plus a 757 as it seeks to cover the four 737 Max aircraft it had in service on 9 March.

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Maarten Visser

Fiji Airways has taken a 737-800 on lease since the grounding began (N739MA, pictured above in 2011 while in service with TUI Group carrier Arkefly). The operator had two Max aircraft in service, Fleets Analyzer shows.

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Rattaphol Kerdkaen/Creative Commons

Samoa Airways is finalising an agreement to wet-lease a 737-800 from Malindo Air. The Malaysian carrier has 24 of the aircraft in service, including the example shown above. Samoa Airways had been set to receive its first Max 9 jet by the end of March.

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Stratolaunch makes first step to space

A notable aviation record fell earlier this month with the maiden flight of what is now the world’s largest aircraft – the Scaled Composites-built twin-fuselage Stratolaunch, whose 117m (385ft) wingspan outstrips even the 97.5m of the Hughes H-4 Hercules flying boat, better known as the Spruce Goose. As another comparison, Stratolaunch also outstrips the 80m wingspan of an Airbus A380.

But where Spruce Goose technically flew just once, lifting its flying boat hull out of the water briefly in 1947, Stratolaunch made a real mark in reaching 17,000ft and 165kts (189mph) during its 2.5h first flight from its construction site in Mojave on 13 April.

Scaled test pilot Evan Thomas, a former US Air Force Lockheed Martin F-16 pilot, described the flight as “smooth, which is exactly what you want the first flight to be”. He added that aircraft rotated “very nicely and smoothly” and “wanted to fly”, and while “we saw a few little things that were off nominal, but really for a first flight it was spot-on”.

He added: “The aircraft felt really nice on touchdown, gear felt good… overall fantastic.”

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First flight

Scaled Composites

Neither Scaled nor Stratolaunch responded to requests for details of the future test campaign. The aircraft – which is the centrepiece of an air-launch service that is intended ultimately to launch rockets big enough to put some 6,000kg (13,200lb) into low-Earth orbits of around 400km altitude – completed at least an initial preliminary design review as long ago as 2012, and was at one time tipped to begin flight trials in 2016.

Scaled built the six-engined Stratolaunch using Pratt & Whitney PW4056 turbofans, and other systems, salvaged from a pair of ex-United Airlines Boeing 747s. The aircraft’s published maximum take-off weight is 589,670kg, including 226,796kg payload. Operational range is 1,000nm (1,852km).

The early plan was for Stratolaunch to carry a SpaceX-built rocket to launch altitude of 35,000ft, but SpaceX has dropped out of the scheme. Instead, Stratolaunch will start – from 2020, according to its literature – by flying the well-proven Pegasus rocket, built by Orbital Sciences and currently air-launched from its own, modified Lockheed L-1011. Stratolaunch will be able to carry up to three Pegasus rockets, each able to put 370kg payload to low-Earth orbit.

Stratolaunch also claims to be developing a “medium launch vehicle” with 3,400kg capacity for a 2022 first flight. The 6,000kg rocket – in “early development”, according to Stratolaunch – will be a construction of three medium launch vehicle cores. At the design study phase is a fully reusable space plane, for cargo or crew missions.

Stratolaunch should in any case be beaten to a launch debut by Virgin Orbit, which is in advanced stages of readying its 21m two-stage LauncherOne – built in-house in Long Beach, California along with its Newton engines, and billed as capable of orbiting payloads of up to about 450-500kg. Virgin Orbit closed 2018 with a captive-carry test flight, and expects to progress to first launch this year.

The two projects share a lineage. Paul Allen, the Microsoft co-founder who died in 2018, was leader of the team that in 2004 won the $10 million Ansari X-Prize, for the first private venture to put a crewed and reusable craft into space twice within two weeks. The WhiteKnight twin-fuselage carrier aircraft and SpaceShipOne rocketplane-glider that won the X-Prize was built by Scaled, under its founder Burt Rutan. That project inspired Virgin Group boss Richard Branson to start his Virgin Galactic sub-orbital tourism venture – using Scaled-built craft that are beefed-up versions of WhiteKnight and SpaceShipOne.

The Virgin Orbit business was later spun off to pursue the growing market for satellite launches. Allen, meanwhile, founded Stratolaunch. For its part, Scaled Composites was bought by Northrop Grumman in 2007, and Burt Rutan retired in 2011.

The two programmes, however, have diverged dramatically in terms of scale. Virgin Orbit’s carrier aircraft is an ex-Virgin Atlantic 747-400, using the so-called “fifth engine” carry point – a standard 747 feature – to secure LauncherOne underneath the left wing. Stratolaunch will carry its payload, or payloads, under its centre wing, between the twin fuselages. By design, it has the ground clearance to carry vastly larger rockets than Virgin’s aptly-named Cosmic Girl. Indeed, Stratolaunch’s planned medium-sized launcher will be so large as to need wings to make the turn to vertical after drop and ignition.

But what Virgin Orbit may lack in size, it gains in flexibility. As vice president special operations Will Pomerantz told FlightGlobal earlier this year, the choice of a 747 builds on the huge operational experience that goes with such a popular type, while also giving Virgin Orbit a relatively easy route to replacing or expanding its fleet. As Pomerantz notes, there are many 747s available for “single-digit millions of dollars”. The modifications to Cosmic Girl took a year, but this could probably be reproduced more quickly.

A bigger fleet may be key to Virgin expanding. At last summer’s Farnborough air show it sealed a deal with Newquay airport in Cornwall to offer launch services from that westerly tip of Great Britain from 2021. And, earlier this month, Virgin announced it would offer launches from Guam, in the Pacific.

Air launch may never compete with traditional vertical launches for the biggest payloads, but it offers several advantages. By lifting the rocket above the thickest part of the atmosphere before lighting it off, stresses on the rocket fairing are reduced, and the rocket motor can be optimised for early-flight performance in thin air. Moreover, a vertical launch invariably ends with significant pad refurbishment.

Another big advantage of air launch is mobility, as launch is possible from pretty much any location with a long enough runway. A carrier aircraft can fly over the sea – clear of populated areas on the ground – and point north to initiate a polar orbit, or east for a more equatorial trajectory. The actual launch point can be chosen to best suit the mission or weather.

And air launch naturally incorporates a fully-reusable first stage. As with any normal airline operation, the carrier aircraft is readied for its next mission with none of the elaborate, and costly, recovery and refurbishment needed to re-fly a rocket booster. Normal between-flight inspection and refuelling does the trick, so the launch rate can easily match demand for trips to space.

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Scaled Composites

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Stratolaunch v other large aircraft; this illustration no longer represents the actual Stratolaunch fuselage shape, but the wingspans stand for comparison

Mwarren us/wikimedia commons

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HAL HJT-36 IJT flies after three year hiatus

Hindustan Aeronautics has recommenced flight testing of its HJT-36 Intermediate Jet Trainer (IJT) from its Bengaluru production centre.

“The flight was flawless and its success is an important step towards the IJT programme,” says HAL.

“The flight testing of IJT (HJT-36), designed and developed by HAL for the stage-II training of IAF pilots was put on hold after the aircraft had encountered problem in the spin test flights in the year 2016.”

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Hindustan Aeronautics

Following these issues, HAL says it undertook modifications of the aircraft “based on comprehensive wind tunnel studies.”

The IJT has had a long, troubled history since its commencement in 1999, with the most recent spin issue capping production. Prior to this, in 2014, HAL called for outside help to reduce the aircraft’s weight.

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Hindustan Aeronautics

India’s defence ministry has been openly critical about the programme. In February 2014 it issued a request for information for a new intermediate jet trainer. It has also expressed concern about the serviceability of the type’s engine, the Russian-made NPO Saturn AL-55I.

In addition, prototypes suffered accidents in 2007 and 2008, one of which occurred at the 2007 installment of the Aero India show in Bengaluru.

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