The output of a jet engine declines, broadly speaking, in proportion to the density of the air in which it operates. You can’t turbocharge a jet engine because the engine itself is fundamentally a self-propelled turbocharger. On the other hand, at high speeds, a jet profits from ram effect, which its compressor compounds, while lower ambient density reduces resistance to the outflow from the exhaust nozzle. Jets therefore operate more efficiently—that is, require less fuel per unit of thrust—at high speed and altitude than they do when flying low and slow. //

The situation of the propeller is different. The engine driving the propeller can be turbocharged and may maintain sea-level power up to a high altitude. But as the density of the air diminishes, the propeller blades have less to work with. Once they are at their optimal angle of attack, the only way to maintain thrust against increasingly rarefied air is to increase the area, number or speed of the propeller blades.

At the same time, as the airplane takes advantage of thinner air by increasing its true airspeed—which is the main reason for wanting to fly high in the first place—the pitch angle of the propeller blades, governed by both their own rotational velocity and the forward speed of the airplane, must increase. As blade pitch increases, the lift vector of each blade points farther and farther away from the thrust axis. This difficulty might be alleviated if it were actually possible to spin the propeller faster, but in fact, the faster the airplane goes, the slower the propeller must turn to keep its tip speeds away from the transonic drag rise. The efficiency of a given propeller therefore decreases as speed and altitude increase.

Schiphol Airport in Amsterdam plans to purchase two TaxiBots to move aircraft from the gate to the runway instead of using their own jet power, according to operator Royal Schiphol Group. It’s part of the airport’s effort to reduce pollution and make operations more sustainable.

Airports in Delhi and Bangalore, India, have conducted trials with a special aircraft tow vehicle. And Lufthansa tested a TaxiBot seven years ago. But Schiphol is the first airport in the world that wants to introduce sustainable taxiing on a large scale.

The TaxiBot is a semi-robotic hybrid towing vehicle made by Smart Airport Systems under license from Israel Aircraft Industries for taxiing airplanes with their power off. The system is based on a vehicle that connects to the aircraft and is controlled by the pilot. The special towing vehicles can reduce fuel consumption and noxious emissions, including CO2, as much as 85% and reduce noise pollution by 60%, according to the company. And it improves efficiency by reducing wasted time at the gate during engine start-up, speeding up aircraft turn times.

A previous trial at Schiphol showed that sustainable taxiing leads to 50% less fuel consumption during taxiing, in the process lowering CO2, nitrogen oxides and ultrafine particle emissions. Given the distance involved, these fuel savings can reach up to 65% percent when aircraft taxi to Schiphol’s runway, the airport operator said.

The most-watched aircraft on the flight tracking App Flightradar 24 are a Global Hawk unmanned spy plane and USAF KC135 and KC10 tankers.

The unmanned Global Hawk has been flying over the Black Sea just south of Russia’s naval base at Sevastopol while the KC135 (Boeing 707s) and KC10 (DC-10) tankers have been stationed over Romania and Poland.

Over 58,000 people are watching the activities of the Global Hawk which has a call sign of “Forte12” or “Forte11”.

The $170 million aircraft is piloted remotely and operates from Italy.

It has an endurance of about 32 hours and can fly over 22,000km at an altitude of 18,000m.

In this post we will compile all information on impacts of the Russian invasion of Ukraine on civil aviation around the world. Check back for continuing updates as developments occur.

An otherwise ordinary building in Costa do Valado, Portugal, on national road N335, near the city of Aveiro, was transformed half a century ago in the grand Portuguese tradition of azulejos - the art of using hand painted, glazed ceramic tiles to depict scenes.
 
In this case the tiles - made by the Aleluia ceramic company in Aveiro (still in operation) - show a pristine image of Pan Am's Jet Clipper America, along with a bit of advertising: "More jets to more places" in Portuguese. The billboard, for lack of a more appropriate term, must date from the days when Pan Am's Boeing 707's represented the epitome of air travel, before the advent of the jumbo jets which came to dominate international air routes at the beginning of the 1970's. The beautiful colors still stand out with vibrancy and impact, and the careful depiction of Pan American's Clipper has lost nothing of its visual attraction despite the loss of some of the tiles at the bottom of the work.

When I was last down at Edwards AFB, I also spent some time at what is now known as Armstrong Flight Research Center. Before the name change in 2014, it had been famously titled the Dryden Flight Research Center. During my time with the awesome public affairs team there, a photo on the wall grabbed my attention. It was an incredible image of one of NASA's two Shuttle Carrier Aircraft (SCA) with the Orbiter Endeavor mated to its back as it flew over a gorgeous desert landscape. But what made the shot so amazing was how the perspective was from directly above, looking down.

I was told that the photo, taken in December of 2008 as Endeavor made its voyage back to Kennedy Space Center in Florida, was one of the most beloved in at the installation and that it was shot by one of NASA's most acclaimed photographers, Carla Thomas. If I remember correctly, the photo was planned ahead of time and executed perfectly from the back seat of Armstrong's F/A-18B. The aircraft had rolled inverted—or near inverted—to capture the unique angle of the loaded-up SCA.

The use of an IRCM system to protect NASA's prized shuttle-carrying 747s during its 1983 visit to the Paris Air Show and other stops along the way is certainly intriguing. What started out as a technical interest for us turned into something of a Cold War mystery. The big question remains: what intelligence led to such a drastic measure being taken and who supplied that intelligence to NASA?

Airbus A380 landing in a crosswind Airplane

APUs became common in the 1960s, with Boeing including the first commercial APU in the 727 in 1963. While the technology had existed in military planes as early as World War 1, their move to commercial flying came as flying became more popular.

The presence of an APU in the 727 allowed airlines to avoid reliance on ground power at smaller airports. The turbine came to be included in all subsequent Boeing aircraft, including the 737 and 747 families. Since then, all modern jets and even some turboprops have come with their own APUs.

during early flight testing at Area 51 with the A-12s, Jim Eastham told me that A-12 #128 flew as fast as any A-12 during testing. On the particular day that the A-12 red lined everything.

“During a routine top speed envelope expansion flight, A-12 #128 was having a hard time getting past Mach 2.7 as the outside air was too warm. The reason for the flight test card that day was to validate a new inlet bypass door schedule.

“Jim said he dropped the nose down a bit to see if he could at least reach Mach 3.0. Out of nowhere, Jim hit good air and in the dive with good air he red lined everything. He went into his descent profile and headed back to the test site.”

Goodall concludes:

“When all was said and done; and for a very brief 15 seconds, Jim hit Mach 3.56, or just under 2,400 mph. Mind you, this was a one-time event and was never duplicated.”

Detailed Photos of Airliners Up Close

Up-close photos of the Boeing 727-100 series

I know the Boeing 777 and 787 run on Fly-By-Wire. I was wondering:

• Do they have the Alpha Floor or Flight Envelope protections Airbus aircraft have?
• Do they have force feedback/force feel? The 737, for example, is connected using physical cables that move the flight control surfaces, so you can feel the yoke trying to move and when there is turbulence, it will actually shake a bit. This can't be felt with an Airbus sidestick. Can you feel this in Boeing Fly-By-Wire aircraft?
• When banking (without any pitch input), will the aircraft start to descend, or does the system counteract it like in an Airbus? In non Fly-By-Wire aircraft, they will start to descend a bit when banking, but Airbus Fly-By-Wire counteracts it by adjusting stabilizer trim. //

1. Do they have the Alpha Floor or Flight Envelope protections Airbus aircraft have?

The Alpha Floor protection on an Airbus overwrites the thrust setting commanded with the thrust levers to TOGA. Boeing does not do this. The autothrottles (if armed) will engage to prevent a stall, but the computer never overwrites the actual thrust lever position in the cockpit: //

Essentially, the philosophy for the control authority differs:

• Airbus will not let you do control inputs that might get you killed.
• Boeing will stop you from accidentally making control inputs that might get you killed, but you can overwrite them. //

2. Do they have force feedback/force feel?

Yes, unlike an Airbus sidestick the Boeing 777 and 787 simulate the forces on the yoke and therefore provide force feedback:

UPDATE (Thu Jan 20): After the debacle on Tuesday, with the cancellation of 777 and 747-8 flights by multiple international airlines, it seems the FAA was embarrassed (or forced) into accelerating the issuance of AMOC approvals for additional altimeters, approving the 777 on Wednesday morning, and the number of altimeters approved and percentage of the US fleet covered has now grown very quickly:
Tuesday Jan 18: 2 altimeters and 45% of the US fleet
Wednesday Jan 19: 5 altimeters and 62% of the US fleet
Thursday Jan 20: 13 altimeters and 78% of the US fleet.

The result has been that most disruption has been avoided, although regional jets remain a concern, with some problems resulting from low visibility. However, the rapid pace of approvals, and the expectation from airlines that there won’t be “any material disruption going forward”, further discredits the FAA’s fearmongering over the weekend, not least because an AMOC has now been issued covering all 787 jets, which were supposedly the cause of greatest alarm. Suggestions that airlines would need to “swap out the altimeters” in a process lasting years and costing billions of dollars, also appear to be well wide of the mark. //

But the FAA’s statements appear to confirm that they are only issuing AMOCs approving altimeters to operate while the current 5G deployment restrictions remain in place: “The new safety buffer announced Tuesday around airports in the 5G deployment further expanded the number of airports available to planes with previously cleared altimeters to perform low-visibility landings.”

So it is perhaps no wonder Boeing is refusing to comment because they don’t want to get into a public shouting match with the FAA, despite the behind the scenes confrontation over the 777 at the beginning of this week outlined above. But you can be sure that many aviation interests are demanding that the restrictions continue permanently and the FAA is preparing for another showdown on July 5th, when the current six month period of restrictions is set to expire.

All barking up the wrong tree.

The FAA should have evaluated some actual altimeters before the FCC approved the use of C-Band for 5G and fed into that process.

This, coupled with the 737Max debacle - means heads really have to roll at the FAA. Problems with both attitude and competence.

Prior would have been challenging. The FAA was unusure how much spectrum to allocate to 5G. The band in question is 3.7 to 4.2 GHz. Prior to 2020 it was ALL used for fixed sattelite service (FSS). The FCC had a long negotiated process to determine how much or little or that would be reorganized to be used for mobile services (5G) and how much would remain as FSS. That dividing line would determine how far the new 5G c-band would be from the radio altimeter band. The FCC looked at reallocating as little as 100 MHz and as much as all 500 MHz to mobile services (although that was very unlikely). Boeing and the avionic companies simply said don't reallocate more than 400 MHz (5G would end at 4.1 GHz). The FCC reallocated even less. 300 MHz and then stripped off 20 MHz for a guard band so it ended at 3.98 GHz.

So while the FAA maybe could have done some preliminary testing of a few possible scenarios they didn't know the realignment plan until the FCC completed it. Still that happened in 2020 almost two years ago. At that point the FAA should have known that baring credible actual evidence of interference the auction and rollout would eventually happen. They could have mandated testing then or a year later when the auction was completed.

Image

After stalling for almost two years, FAA cleared 78% of planes in the past week. //

These statements marked a sudden shift, coming just three days after Parker and Kirby signed a letter claiming that 5G on the C-band would cause "catastrophic disruption" to air travel. //

The biggest recent development is that the FAA finally started a process to evaluate and approve altimeters after claiming without proof that 5G on C-Band spectrum (3.7 to 3.98 GHz) would disrupt altimeters that use spectrum from 4.2 GHz to 4.4 GHz. While the Federal Communications Commission created a 220 MHz guard band to protect airplane equipment, poorly built altimeters may be unable to filter out transmissions from other spectrum bands.

The FAA didn't start its process of evaluating the actual altimeters used by airplanes after February 2020, when the Federal Communications Commission approved the use of C-Band spectrum for 5G. The FAA also didn't start this evaluation process after the FCC auctioned off the spectrum to wireless carriers in February 2021. Instead, the FAA continued arguing that 5G deployment should be blocked long after carriers started preparing their equipment and towers to use the C-band. //

The FAA saying that deployment at these frequencies might cause problems doesn't make any sense at all because its already been done. Is the US some special case where laws of physics don't apply?

As someone joked in another post, metric vs imperial wavelengths? //

The FAA could have been in CYA mode even three months ago and had 99.9% of aircraft cleared prior to the Jan 17th go live date. They didn't even start to do their job until Jan 4th. I would point out the original go live date was 1 Nov so the FAA got a homework extension twice and still didn't turn it in on time. //

The FAA came up with a testing regime this year and now we've got most altimeters in use having been cleared, just 3 weeks later. The resources it and the airline industry spent fighting 5G C-band deployment seem quite clearly to far exceed the resources it spent on testing and discovering there's actually no problem. //

I can't help but think that some airline CEOs tinfoil hat wearing, 5G conspiracist brother-in-law got a hold of them at a holiday get together to let him know of the imminent air disaster due to the 5G transmitters and now caused this ridiculousness for the past several weeks.

The rollout of 5G cellular phone service has started affecting operations around the country—a terrific story in The Air Current by Jon Ostrower detailed the confusion at Palm Beach International yesterday, writing, “The aircraft’s radar altitude abruptly ran down to zero, causing repeated loud aural warnings: PULL UP WHOOP WHOOP DON’T SINK TOO LOW GEAR. The flight landed without incident in good weather, but it wasn’t the first time. ‘Exact same location multiple times the past two weeks,’ the pilot, who was on the flight deck for both anomalies, told The Air Current.”

And now Airbus has issued guidance to pilots that details the many things that could go wrong with their planes’ systems if the radar altimeter, built into a handful of systems, including Autoland and Ground Proximity Warning Systems, were to get erroneous readings.

https://theaircurrent.com/aviation-safety/5g-network-disruption-cluster/

On May 23, 2021, at approximately 6:45 UTC, Churo and Fnu Lnu arrived at the operations room of the Minsk area air traffic control center with responsibility for Belarusian airspace. Churo and Fnu Lnu conveyed the purported bomb threat to the controllers on duty, even though the Flight had not yet departed Athens. Churo and Fnu Lnu specifically crafted the threat to coerce the pilots of the Flight to avoid continuing to their final destination of Vilnius, by claiming that the purported bomb would explode if the Flight landed there.

In addition, Churo and Fnu Lnu took the telling steps of directing that the Flight be diverted specifically to Minsk, and even though the Flight was still in the adjacent airspace of Ukraine, prohibiting the Minsk air traffic control center from making any notification to Ukrainian authorities of the purported bomb threat. This helped to ensure that the Flight would enter Belarusian airspace, and the plot to obtain and exercise control over the Flight could be executed. Fnu Lnu remained in the operations room at the Minsk air traffic control center from the time that he and Churo conveyed the purported bomb threat and directed that the Flight divert to Minsk, until shortly before the Flight landed in Minsk after being diverted, in order to ensure that the diversion plot was successfully executed.

Once the Flight reached Belarusian airspace, Fnu Lnu instructed the senior air traffic controller who was responsible for communicating with the Flight to inform the pilots of the purported bomb threat, describe that the threat had been sent by email, and make specific statements to ensure the threat seemed credible and to coerce the Flight to divert to Minsk. For example, Fnu Lnu directed that the air traffic controller should falsely inform the pilots that the threat to the aircraft was a level “red” – the most specific and credible category of threat. Fnu Lnu provided updates on the execution of the plot in real time to his superior in the Belarusian security services, Andry Antolievich Lnu, at one point expressing concern that the pilots might be stalling for time and the Flight might soon leave Belarusian airspace, which would jeopardize the success of their diversion scheme. In response to the false information conveyed as part of the defendants’ plot, the pilots of the Flight ultimately declared an emergency and diverted to Minsk National Airport, in accordance with the directives from Churo and Fnu Lnu.

Once the Flight landed in Minsk, Fnu Lnu left the air traffic control operations room and went to the airport tarmac. The Flight was met by Belarusian security services personnel, including individuals dressed in camouflage military-style uniforms, some of whom were wearing ski masks and carrying visible firearms. Fnu Lnu remained on the tarmac supervising the security forces and monitoring the screening of the passengers as they disembarked. Belarusian security services personnel then instructed the passengers to board one of several airport passenger buses.

Belarusian authorities boarded one of the buses and asked Individual-1 to come forward and identify himself, demonstrating that Belarusian authorities were aware that Individual-1 was on board the Flight. Individual-1 was escorted off the bus, where uniformed Belarusian officers separately searched him again on the airport tarmac. Belarusian officers then escorted Individual-1 back onto the bus and traveled with Individual-1 and the rest of the passengers to the airport terminal. Once the bus arrived at the terminal, the Flight’s passengers were detained in an area of the terminal secured by Belarusian security services. Additional Belarusian security officers met Individual-1 and the officers accompanying him, escorted Individual-1 away from the remaining passengers and detained Individual-1. One group of passengers from the Flight, including multiple U.S. nationals and Individual-2, was detained in a narrow hallway for approximately three hours at the airport. During that time, Belarusian authorities also escorted Individual-2 away from the other passengers and detained Individual-2. The Flight was ultimately allowed to depart from Minsk and continue to its original destination of Vilnius later that evening. No bomb was ever on the Flight. //

Soon after the diversion of the Flight, Belarusian government officials began to cover up what had happened. On or about May 24, 2021, the day after the Flight was diverted, Churo appeared at a press conference in Belarus with other Belarusian officials to address the Flight’s diversion. During the press conference, Churo stated falsely the Belarusian authorities had “done everything according to their technology and their job responsibilities” in handling the Flight. In reality, Churo knew that he and his co-conspirators had contrived the false bomb threat and had directed the Flight to divert to Minsk so that Belarusian security services could arrest Individual-1 and Individual-2. To further conceal the defendants’ plot, Kazyuchits directed Belarusian air traffic authorities to create false incident reports, including by doctoring the reports to misrepresent that the bomb threat was received at approximately the same time that the Flight entered Belarusian airspace and omit the fact that Fnu Lnu of the Belarusian security services was present in the operations room and directed activity during the Flight’s diversion. //

An indictment is merely an allegation, and all defendants are presumed innocent until proven guilty beyond a reasonable doubt in a court of law.

Ryanair flight 4978 from Athens to Vilnius was forcibly diverted to Minsk while passing through Belarus airspace on Sunday, 23 May. The flight was 72 kilometers from Vilnius (VNO) when it made a 180 degree turn before diverting to Minsk at the behest of authorities in Belarus. The aircraft was allowed to depart about 7 hours after landing. //

On 20 January 2022, the United States charged four Belarusian government officials with aircraft piracy for forcibly diverting Ryanair flight 4978. The US was able to bring the charges because four of the passengers onboard the flight were US nationals. The charging documents for the first time lay out US version of how the flight was diverted. Those charged are either employees of the state air navigation service provider or state security services. //

https://www.justice.gov/opa/pr/belarusian-government-officials-charged-aircraft-piracy-diverting-ryanair-flight-4978-arrest