76

It's an emergency escape hatch. There are inertial reels in the cockpit ceiling adjacent to the hatch to allow the cockpit crew to exit the airplane. See this link for an account of their use escaping the aircraft during a hijacking. There were five reels in the 747-100/200 aircraft. The cockpit had five seats: pilot, co-pilot, flight engineer, and two ...


74

Several reasons: A380s are really expensive. Unit cost for an A380, depending on interior appointments, is about \$375 million. The 747-8 is about \$357 million. The 777-300ER is about \$320 million, the last variants of the A340 about \$275 million, and the 787 about \$200 million. The 380 might be the biggest airliner ever to fly, but it's also the most ...


58

The basic design of the Boeing 747 was originally developed to for the US military's CX-HLS program for a large cargo aircraft. One of the main requirements of the program was for cargo to be loaded from the nose, and placing the cockpit above the main cabin made this possible. The Lockheed C-5 Galaxy was selected, but Boeing carried the same features over ...


52

The 747-200 derivatives used for transporting the President of the United States are VC-25's operated and maintained by the United States Air Force. The US Air Force tends to keep planes for a long time, as they still operate 707 and B-52 aircraft twice as old as these 747's. The E-4 aircraft, also based on the 747-200, have been in service for 40 years. The ...


48

Flare (pyrotechnic) type According to Wikipedia and ynetnews.com, the flare system burns at low temperatures and doesn't pose a danger. Nonetheless Europe in 2006 objected to it and Switzerland threatened to ground El Al if such system was found on board. "If we catch Israeli planes fitted with this system in our airports, they will be grounded," ...


47

One of the main reasons the 747 was given the ability to ferry an engine was due to the lack of large cargo aircraft available at the time. Don't forget the 747 was a major game changer when it came out, it was designed to replace the 707/DC-8, and was almost twice the size of these aircraft. As a result, there just wasn't anything available to transport a ...


45

They only change one, because that one is a new engine that is being tested. If you are testing a new engine you change 1 at first so if it fails you have 3 others. If you change all 4 and there is a systematic defect in the design, now you have 0 good engines instead of 3. You will also see that the test engine isn't always one suitable for a 747. ...


44

This podcast with one of the pilots answers just about every question on the shuttle carrier you could have and it's worth a full listen. But to cover the flight dynamics, I would skip to 50:33 minutes, where the pilot states (please note there is no official transcript of the podcast and I typed this as I listened to it, please see the official podcast for ...


42

Commercial aircraft are designed for a service life of about 25 to 30 years. The 747-200 is no exception. The VC-25A entered into service in 1990, so it has operated now for almost 25 year. The number of flights will be low compared to aircraft in commercial service, so the aircraft is not worn out at all. Replacing it with a new aircraft as soon as a new ...


37

The "fifth engine mount" option on the 747 is not designed to handle a running engine. It was an option used only by Qantas as a means of ferrying spare engines to remote locations, where flying a plane for a long distance to a maintenance facility on three engines was not possible. Only four of the Qantas fleet of 747s (totalling more than 60 aircraft) had ...


36

No. The Boeing 747 was not designed for supersonic flight, though during testing, it was pushed quite close to the sonic speed: Tom Cole, a spokesman at Boeing Commercial Airplane Co., said original flight tests of 747s conducted in 1969 and 1970 took 747-100 models to speeds of Mach 0.99. However, the aircraft is not built for sustained supersonic ...


36

Quite a few, actually. British Airways is the largest operator of B747-400 and flies a number of routes: Where does the Boeing 747-400 fly? The aircraft operates on a variety of routes, including: Beijing Boston Cape Town Dubai Lagos Las Vegas Mexico Miami New York (JFK) Phoenix San Francisco Toronto Air China operates both 747-...


35

Simply, more engines = more power, and power is needed for several things, the first of which is, taking off. At max takeoff weight, a multi-engine aircraft has to be able to lose one engine (after reaching the go/no-go speed) and safely continue the takeoff, which means that if you could just barely fly on 3 motors, you're going to have to have 4 to meet ...


32

According to the Washington Post, Air Force One never refueled in mid-air with the president on board. If it needs to refuel, it usually does so at one of the U.S. military bases across the world. The retrofitted Boeing 747 that usually serves as the presidential jet can indeed refuel in flight — but it has never done so with the president on board, ...


31

Boeing actually never expected the 747 to be so successful. They thought supersonic aircraft were the future. But Boeing knew that an aircraft the size of a 747 would be great for the cargo market. So they designed one aircraft that could be easiy converted into a cargo version. The cargo 747s can literally open their nose. It is quite impressive. To ...


31

ETOPS stands for Extended-range Twin-engine Operational Performance Standards, a rule which permits twin engine aircrafts to fly routes which, at some point, is more than 60 minutes flying time away from the nearest airport suitable for emergency landing. ETOPS may also be interpreted as Engines Turn or Passengers Swim. It is not a rule which applies after ...


30

Boeing Boeing would have used DU because it had the right combination of physical characteristics and cost. Their tests showed that the radiation exposure for workers was low (2.6% of the statutory "safe" level). In most cases the exposure was so low as to be not detectable. Radiation Passengers on aircraft are exposed to cosmic radiation at much higher ...


30

No, it wasn't considered during the development. (Bowman) The 747 came from Boeing's studies for the USAF CX-Heavy Logistics System program, which was won by the Lockheed C-5 Galaxy. See: What was Boeing's competitor to the C-5? That project called for four engines, and an engine was designed for that purpose. See: How was the high-bypass concept ...


28

Interesting question. I think it could be done in the right conditions if you are willing to accept some damage and depending on the runway. Is the runway level or uphill/downhill? If you could land uphill in a high wind that was almost all headwind, I believe you could either do it or would overrun the runway at a low speed. Airplanes slow down really ...


28

There is page by cryptome with documentation about AF1 rescue options. According to the "TECHNICAL ORDER 00-105E-9, 1 FEBRUARY 2006, REVISION 11." (15 April 2006), slide 71 "AIRSTAIR OPERATION VC-25A", Boeing VC-25 has only two exits equipped with own airstairs, only at doors from lower compartments. Doors at main deck have no integrated airstairs. Source ...


28

It's not as fuel-efficient as a twin engine aircraft and doesn't offer as much scheduling flexibility. Comparing the 747 in 1969 to the A380 today isn't really a good comparison. A better comparison would be comparing both of them today. In 1969, the 747 was revolutionary. It was the first large jet that could get a lot of people from one side of the world ...


28

There are many airlines still operating the 747 in passenger service. Lufthansa has bought the 747-8, the last delivery was in April 2015, so I'd expect that the 747 will be in passenger service for at least another 20 years. Here's your choice: KLM Lufthansa (both the Boeing 747-400 and 747-8) British Airways Thai Airways Virgin Atlantic Iran Air (747-...


28

There are still lots of 747's in scheduled passenger service and at least a few dozen of them will almost certainly remain so for the next 20+ years. 747-400 British Airways has 36 of them with retirement scheduled for 2024. Virgin Atlantic has 8 of them with retirement beginning in 2019. KLM has 14 of them Qantas has 10 of them China Airlines still has ...


27

The other answers are spot on, but I'd like to address one part, which is the "later down the runway." It is by no means "later." (YouTube) In the frame grab above of a 747-400 (taken at 1:12), the captain had already called out "takeoff thrust," the TO/GA system had set the pre-programmed thrust setting, and the 747 wasn't even at the piano keys. (...


26

They have seats for couriers, same as factory freighters, but roomier. Note: From the -400BCF type certificate: There are no provisions for the carriage of passengers. A maximum of 19 couriers can occupy the aft cabin of the upper deck as defined in AFM. Source: airplane-pictures.net Above is the upper deck of a -400BCF (converted freighter). And ...


25

Typically, a little gain is obtained. Larger airplanes use anti-skid technology. Anti-skid works by modulating brake pressure to ensure the tires never skid. It's important to understand the relation between a tire's load, brake pressure, and actual retarding force. First, look at this image : It shows how as you increase pressure and the wheel starts ...


25

The question speaks of a very old 747 landing tutorial. And as such I take that to mean it would be of a 747-100/200 aircraft, and that's the reference point I'm answering from. First, concerning the comments below the question that wonder whether you have to worry about unwanted objects on a runway at an international airport, there is no such thing as a ...


25

Fuel tanks take most of the space in aircraft wings, but not all. There are other things on wings too. They are ailerons, flaps, slats, air brakes. On most airliners, the engines are attached to the wings too, so their assembly takes up space. On the two aircraft of your interest, here are the pictures: A380 (its nickname is not jumbo, but superjumbo) ...


24

The descent angle helps to reduce the lift that the wing needs to provide, in two ways. It leads the aircraft into higher density air, where more absolute lift is possible at the same Mach number. That takes a while, but a more immediate effect comes from pointing the aircraft's nose downwards. Then, part of the gravity-induced forces can be counteracted by ...


24

In addition to what Ralph mentioned, up until the mid 1980s, regulations required that aircraft operating long over-water routes or other such routes with a lack of places to divert in the case of emergency must have at least 3 engines. Specifically, this applied to any route that was more than 60 minutes from a diversionary field in areas subject to FAA ...


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