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Why does the Boeing 787 have fewer cockpit windows? The 787 has only 4 cockpit windows, whereas other airplanes have 6. Here is a comparison between the 787 and 777: enter image description here ^ 787 V.S. 777 v enter image description here

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    $\begingroup$ Related $\endgroup$ – Pondlife Dec 8 '17 at 15:51
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    $\begingroup$ That image orientation makes the 777 look huge! $\endgroup$ – dalearn Dec 8 '17 at 17:36
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    $\begingroup$ It's an Air France so it might have been carrying loads of croissants and other such baked goods. $\endgroup$ – Bob Jarvis Dec 8 '17 at 23:32
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    $\begingroup$ No @BobJarvis , sorry, it's KLM ! ;-) AirFrance planes don't have this color scheme (Yes, I did notice it is written "AF/KLM") $\endgroup$ – kebs Dec 8 '17 at 23:41
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    $\begingroup$ @dalearn might have something to do with the 777 being huge, $\endgroup$ – Harper Dec 9 '17 at 4:23
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It is because of the carbon fibre. This is the same reason that the 787 has bigger passenger windows. Here you can find a link explaining the polarized windows on the 787. Because of its higher tensile strength, you can have bigger windows. Windows are considered weak points in the fuselage where there is no structural reinforcement. This means that the windows have to be supported by the fuselage and structural components around the window. Boeing Pilots do not fly with their elbow out the window during flight, so Boeing removes that feature. They added bigger windows because they could. There is there separation for the six windows because there is support needed.

Hope this helps, Charlie

Carbon Fibre vs Aluminium

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    $\begingroup$ It looks like it's only me, but I don't see how this answers the question. Unless there is too big of a perspective difference, the photos make it like the 787 has less glass than the 777, and less panels, which is the question. With the reasoning about the stronger structure, I would expect more windows, no less; unless, like I said the picture are from such different angles that they don't show that the 787 has actually more glass than the 777. $\endgroup$ – Martin Argerami Dec 9 '17 at 15:47
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    $\begingroup$ @MartinArgerami: You're not alone. Unclear explanation involving the tensile strength (resistance to elongation) of the fuselage and "Boeing Pilots do not fly with their elbow out the window during flight, so Boeing removes that feature". At least the area of the windows and angle of view should be compared. $\endgroup$ – mins Dec 9 '17 at 18:52
  • $\begingroup$ "fly with elbows out the window" ... Hey, that's a ground feature. $\endgroup$ – Joshua Dec 10 '17 at 18:48
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The rules on visibility from the cockpit have been updated.

There are rules and regulations imposed on the view from the cockpit, for very good reasons - collision avoidance for instance. During approach, the pilots must be able to see the runway while on the glide slope, at any COG location. From Torenbeek:

enter image description here

The angle of view forward and downward must be sufficient to allow the pilot to see the approach and/or touchdown zone lights over a distance equal to the distance covered in 3 seconds at the landing speed when the aircraft is

  1. on a glide slope,
  2. at a decision height which places the lowest part of the aircraft at a height of 100 feet above the touchdown zone (see Fig. 3-25) ,
  3. yawing ± 10°,
  4. making an approach with 1,200 feet Runway Visual Range, and
  5. loaded to the most critical weight and center of gravity location.

Some additional requirements from British regulations were:

  • When taxiing, the pilot should be able to see the ground at a maximum of 130 ft trom the airplane, but preferably this distance should be 50 ft or less.
  • When climbing, the pilot should be able to see at least 10° below the horizon and preferably 15-20° below it.
  • When landing, the pilot should be able to see below the horizontal when the airplane is in the tail-down attitude .
  • Another desirable feature is that during taxiing the pilot should be able to see the wingtip on his side of the airplane.

enter image description here

The FAA made a proposed regulation on improved visibility from the cockpit in 1971. However, according to the aerospace industry, this would impose structural limitations on cockpit design with high weight and drag penalties. From FAA AC 25.773-1, published in 1993:

A majority of the commenters responding to Notice 71-2 objected to the proposed amendments. In general, the airplane manufacturers believed the proposed requirements were too stringent and exceeded the state-of-the-art, particularly with respect to the size of transparent panels, considering weight and structural strength necessary to provide clear vision in the specified areas.

The B777 was designed before 1993 and followed older regulations. The view from the cockpit for aircraft designed after 1993 (the 787 for instance) complies with the Advisory Circular 25.773-1, allowing a smaller field of view compared with earlier regulations.

enter image description here

The windows are curved because current technology allows for double curved surfaces that are strong enough for bird impact, although the B787 has had some problems with cracked windshields.. As @PeterKämpf points out, the flat panels of the past required using more of them to keep reasonable aerodynamics, drag and noise: if the panels must be flat, many small panels make for better aerodynamics than a few big panels.

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    $\begingroup$ Thanks for mentioning the curved nature of the newer windows. The flat panels required more sections in the past so the aerodynamics were still acceptable. Cockpit noise should be noticeably lower with curved panels, a clear indication of better aerodynamics. $\endgroup$ – Peter Kämpf Dec 9 '17 at 23:51
  • $\begingroup$ @PeterKämpf Valid point, have included in the answer. $\endgroup$ – Koyovis Dec 10 '17 at 0:07
  • $\begingroup$ This should be the accepted answer! $\endgroup$ – JakeRobb Dec 29 '17 at 15:00
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Having many cockpit windows is a relic of past times, where most of the work was VFR and there were no such things as a TCAS.

Let's take a look at the Boeing 707 for example:

B707 Image Source

As you can see, there are many big windows, even additional small ones at the top to make it easy to spot traffic.

However, IFR and systems like TCAS have made it unnecessary to use many big windows. Today, windows in the cockpit are only needed for take-off, landing and taxi. The rest works automatically.

And if you think: "Why bother, just let those windows in there, the better view is always better". Glass is significantly heavier than the other materials used on aircraft. And as you know, every pound counts in aviation.

This change happens slowly as you can see. That's why the 777 has still got quite big windows and the 787, the current Boeing flagship, smaller and less.

This trend will, of course, continue in the future, until the minimum for above-stated purposes is found.

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    $\begingroup$ There are minimal standards imposed on the view from the cockpit by CFR 14 Part 25. $\endgroup$ – Koyovis Dec 9 '17 at 19:20
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    $\begingroup$ Pilots are required to maintain a lookout for traffic even when IFR. TCAS is not intended to be a substitute for pilots looking out the window. When flying under IFR rules but under visual conditions, pilots may accept instructions which require them to maintain visual separation from traffic that they have in sight. In short, the windows are still very much required. $\endgroup$ – Wayne Conrad Dec 10 '17 at 3:29

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