I’ve heard of many passengers complaining about the FAs locking the dim setting at different phases of the flight. Seems to be something the passengers definitely don’t like. And the passengers cannot change it. What is the reason for locking the window brightnesses?
Why do flight attendants on the 787 lock the dimmable windows at different phases of the flight?
11$\begingroup$ Do you mean for takeoff and landing? If so, this should answer your question: Why open up the window shades before takeoff and landing? $\endgroup$– BianfableJan 7, 2020 at 10:57
2$\begingroup$ @Bianfable while I have heard it for takeoff and landings, a vast majority also say during at cruise altitude. Others have said you can avoid it by suggesting your setting when the FA’s ask, but I don’t see why they would do that when it just defeats the entire purpose. $\endgroup$– George Clooney In a MooneyJan 7, 2020 at 10:59
3$\begingroup$ I don't understand the meaning of "dimmable". Please explain more. Is this some sort of electronic control over how transparent the window is? Does it involve a physical barrier (window shade), or not? A few extra words would help some of us understand the question much better, thank you. Or, I could always ask ASE in a separate question. $\endgroup$– quiet flyerJan 7, 2020 at 18:54
9$\begingroup$ The 787 has electronically-dimmable windows (I believe they use liquid crystals) to change how opaque they are without a physical shutter. $\endgroup$– SkylerJan 7, 2020 at 19:04
7$\begingroup$ @quietflyer The 787 has electrochromic windows (sometimes called "smart glass.") There's a control beneath each window where the passenger can change its opacity, but the cabin crew can override the controls and make them all transparent or opaque during flight phases when all of the windows need to be open or closed. There are no actual physical shades like on most other passenger aircraft. $\endgroup$– reirabJan 7, 2020 at 20:40
On long-haul flights, most passengers will want to sleep, often including when the aircraft is flying through daylight. It's especially common on East-West long-haul flights for lots of people to want to sleep when it's daylight outside the aircraft, since the aircraft will often be crossing many time zones (and, during the summer months, also often flying through regions where it's daylight all day or nearly all day.)
Even on aircraft without dimmable windows, the cabin crew will normally tell passengers to keep window shades closed after the first meal service when the cabin lights are turned out for that reason. On the 787, the crew will dim and lock all of the windows centrally instead of telling the individual passengers to do it and this also prevents a passenger from undimming it and waking everyone up. Unfortunately, that does happen from time to time on aircraft with normal window shades where the crew can't prevent it and it is really annoying when you're trying to sleep if you don't have an eyemask on.
Here are some common examples of the types of long-haul flights where many or most passengers will be trying to sleep during hours where the aircraft is flying through daylight:
Flights from East Asia to the U.S., even though they're typically at least nominally "overnight" flights, will actually spend much of the time flying through daylight. The actual darkness outside will only last a fraction of its usual time, since the aircraft is flying in the same direction as the Earth's rotation at a pretty significant fraction of Earth's rotational velocity.
Flights from Europe to North American typically occur entirely during daylight. While it's 'daytime' on these flights, these days are often (quite literally) long days for travelers, so many will want to try to nap during the middle of the flight.
Late flights from North America to Europe often leave North America within an hour or two of midnight and land in Europe around midday, even though it's only 6-8 hours later. The latter half of the flight takes place in daylight, but passengers will still be trying to sleep.
Summertime flights from North America to East Asia will typically experience midnight sun. Even though these flights often occur almost entirely during 'overnight' hours, their flight paths frequently take them well into the Arctic Circle — sometimes even near the North Pole — where it will be daylight outside, even though it may be near midnight local time. This typically occurs around the middle of the flight, when nearly everyone will be trying to sleep. As most readers of this site will know, the reason these flights fly so far North is because that's actually the shortest path, since Earth is a spheroid. For example, this map shows the shortest-distance path from New York's Kennedy Airport (JFK/KJFK) to Shanghai's Pudong Airport (PVG/ZSPD):
Shortest path from JFK to PVG, generated on gcmap.com
1$\begingroup$ to be exact, at latitudes beyond arctic circle, during summer there will be daylight 24 hours a day, as for a certain period of days depending on how high a latitude you are at, the sun will not set at all. Flying at high altitudes will make this better or worse, depending on whether you do or do not (respectively) like sunlight ;) $\endgroup$– Jpe61Jan 7, 2020 at 20:13
2$\begingroup$ I've known them want the shades down even on fully daytime flights. Sleeping pax are less likely to press the call button. $\endgroup$– RichJan 7, 2020 at 21:53
7$\begingroup$ I get very frustrated with this custom. I fly business or first class on long haul flights, and the amenity pack always includes eye shades. Why do the passengers who want to sleep not use them? My objective on a long haul flight is to adjust as quickly and completely as possible to the new time zone, and exposure to natural daylight when it is daytime there is the best way of doing that. $\endgroup$ Jan 7, 2020 at 23:56
1$\begingroup$ @PatriciaShanahan By nature of being part of the near-disposable amenity kit, the masks are "economy" quality, and I have yet to find a pair that fits comfortably on my face. $\endgroup$ Jan 8, 2020 at 0:06
2$\begingroup$ Also, the majority of the passengers are in economy, where the amenity kits typically aren't provided and it's already much harder to sleep, due to sitting with a slight recline rather than lying down in a flat-bed seat. $\endgroup$– reirabJan 8, 2020 at 0:11
For takeoff and landing, @bianfable pointed out the answer. For longer flights across timezones, they set them to dark in order to not disturb passengers who would like to sleep.
And yes, I personally hate it when they do that and avoid the 787 whenever possible.
1$\begingroup$ Or in my experience, at least, the people who'd rather watch the TV screens. $\endgroup$– jamesqfJan 7, 2020 at 19:00
6$\begingroup$ I hate the B787's electrochromic windows because they change color sooo slowly. When I see something interesting outside, it's impossible to untint the window quickly to take a good quality photo! $\endgroup$– NayukiJan 8, 2020 at 6:16