Hot answers tagged

69

Direct answer Air conditioning causes a large drop in cabin temperature, air humidity present in the air condensates into water droplets. It is similar to mist, fog and clouds. If water droplets enter in contact with a solid they form dew and moisture. Accurately, it is an aerosol of water droplets. Water droplets appear in air when air temperature is ...


28

I see several challenges with this design, both technological and not: Making that design safe enough will be difficult, the structure you add in the cabin would need to be strong enough to maintain rigidity in a crash. That much rigidity would add weight, and would add loads to the structure The pod walls will make it hard to get by people in the single ...


27

Modern airliners use HEPA filters to filter the air before re-circulation. This will remove almost all airborne pathogens like viruses: The overall risk of contracting a disease from an ill person onboard an airplane is similar to that in other confined areas with high occupant density, such as a bus, a subway, or movie theatre for a similar time of ...


26

IF the airliner has HEPA filtration yes, so pathogens floating in the air that happen to get drawn into the recric system would be trapped and not recirculated, so some of the total pathogen load in the cabin, but not all, would be removed. In theory, if you just added a fixed amount of pathogens at the start and just let it run, the concentration would ...


24

The problems I can see with that design: Increased structural weight: all things remaining the same, you will have less payload availability for luggage/cargo. Cabin servicing you either add an elevated kitchen (more weight) or you have to go up those stairs with the carts every time you want to service the cabin. Possible claustrophobia those modules look ...


22

It holds a life raft. In case of ditching in the ocean, the raft would be removed from that compartment and tossed into the water, where it would inflate.


15

In a jet it's going to be pretty much all above 100hz. Most of the noise at cruise is broad spectrum "white noise" from the air flow and the engine core exhaust. The fan however, running at, typically 4000 rpm, with 60 blades say, will be producing a 4000 Hz noise, and this along with the exhaust white noise will be the dominant sound prior to ...


15

What powers the airconditioning on most airliners is APU or main engine compressor bleed, which is being supplied at fairly high pressure, say, 80 psi, and temperature, around 3-400F, to the air conditioning packs. You normally have a choice to select APU or main engine bleed. You will obviously use APU bleed on the ground before engine start, but also may ...


11

Here is an illustration of how cabin pressure changes during a typical commercial flight: image source: http://aerosavvy.com/aircraft-pressurization/ Note how when the pressure outside the aircraft is changing, the pressure inside the aircraft is also changing, but not as much. During the flight shown here, you would experience about the same pressure ...


9

Normally there is some kind of barrier, a bulkhead or curtain, separating the business class and the common folk in steerage. In such a case the sign is to indicate that there is an exit somewhere down yonder beyond the bulkhead. In this case the curtain is not there so the sign kind of hangs there with its nonsensical implication that maybe there is an ...


8

From a luxury round the world flight on several different models of aircraft on several different airlines, a traveler used the exact same sound meter at his seat in either business or first class to measure ambient noise level during cruise. Here is a chart I made of his measurements, including carrier and age of aircraft. As you can see, long haul ...


7

The depicted seating configuration wouldn't fit in a typical wide body aircraft. It would require a jumbo platform, such as the 747 or 380. A wide body aircraft can only do 2+4+2 seating, whereas this configuration requires another 15" aisle. Further, this configuration appears to suggest additional walls and structural components that would increase the ...


7

The video shows the seat-pitch at 42". Current seat pitch is typically around 30-33". I'm pretty skeptical that you can increase seat-pitch by 10" and still increase seating, no matter how much seats are stacked on top of each other. Also, the video shows seating in a 2-2-2-2 configuration, with 3 aisles. Typical wide-body seating is 2-4-2, 2-5-2, 3-3-...


7

If you're talking about one of the jumpseats in the flight deck (as opposed to the ones FAs use in the passenger cabin,) then, no, it's definitely not allowed during flight, at least not in the U.S. or E.U. It may be allowed elsewhere, though. The United States Relevant regulations for the U.S.: 14 CFR 121.547 for domestic air carriers and 14 CFR 129.28 for ...


6

As a passenger: In the forward bulkhead section of economy class (lower deck) there is almost no engine noise in the A380. If you listen carefully, you can hear it. I was actually surprised at how quiet it was that I didn't need my noise cancelling headphones. In the upper deck, there is no engine noise to speak of. In the forward section of the 777 (...


6

"they can obstruct evacuation in case of emergency situation." Thats the reason. "In my opinion, there is no safety risk" Please describe your qualifications and level of expertise to have a valid opinion. "Does it really pose a safety risk and compromise flight safety in a level flight?" If an emergency occurs at cruising altitude, and the plane begins an ...


6

Cost. Those would be expensive, and the business is bad already. Now, you might think that just any mesh, fabric or membrane would do, but but to be effective against the sperad of viruses, nope. Discomfort. Imagine how it would feel to be bagged up like that for hours. Again, despite the membrane being a "breathing" sort, it would still get rather ...


5

There's an option for a tail mounted camera for the passenger entertainment system (PES). It's the same one they use on widebody jets, but it's not hooked up to the cockpit for taxi purposes. Airbus press release says Designed for a private customer, this cabin seats just over 30 passengers and includes such features as touch-screen technology, advanced ...


5

Systems vary. Transport aircraft and larger biz aircraft have airpacks handling the AC and at flight idle power settings there is less bleed air, and pressurization is a priority. The packs simply do not have full power when in a flight idle descent on many aircraft. The aircraft I routinely fly have separate radial compressor driven refrigerant systems,...


5

A Reuters article confirms the humidity just comes from the passengers, on the 787 at anyway: (...) the air is dry and moisture comes mostly from passengers. And this Flight Global article: (...) the system does not add moisture through active humidifiers. This APEX article has no discussion of higher cabin pressure being an influence on humidity. ...


5

It's condensed water droplets. Outside air with high humidity is reduced in temperature from 28 - 20 ºC (after going through a compression - cooling - expansion cycle), and some of the water vapour condenses since colder air cannot contain as much water vapour as warmer air. The condenser is located before the expansion turbine. Indeed like @David Richerby ...


5

I can't definitively identify the true origin of the chimes; but the earliest reference to them I can find is in: ARINC Characteristic 715-3 Airborne Passenger Address Amplifier (PA AMP) This standard describes the characteristics of a PA AMP designed for installation in commercial aircraft. Its function is to amplify control voice, music and internally ...


5

See the FAA FAR Here for the full regulations but it says: (b) Except as provided in paragraphs (b)(1) and (b)(2) of this section, each person on board an airplane operated under this part shall occupy an approved seat or berth with a separate safety belt properly secured about him or her during movement on the surface, takeoff, and landing. the ...


5

I can tell you that in economy, the 777 noise was, in my opinion, almost unbearable. The A380 was almost silent. I have been on both on long haul to the uk, and their is a world of difference in the noise levels. Will never fly 777 again.


5

The 737-400, -800, and -900 have two cabin air conditioning zones plus the cockpit. The rest have one plus the cockpit. Both packs are on in normal operation because they are slightly more efficient at lower flow rates. It also is safer as no immediate action is necessary to prevent depressurization if a pack fails. Temperature is regulated separately. The ...


4

Yes, it is possible. It happened to me on KLM, on a flight from Singapore to Amsterdam maybe 15 years ago. I had booked business, but KLM had overbooked and offered me to choose between a much later flight or economy. This was the Jakarta - Singapore - Shipol flight with only 8 business seats, operated with a 747 combi. The economy seat was so small that I ...


4

As a generic answer, the only setting the crew inputs in most pressurization systems is the destination field elevation. This determines the pressure schedule on descent, and the system will use a cabin altitude descent rate that will put the pressure differential to near zero, usually slightly positive (that is, a hundred feet or so below field elevation) ...


4

A copy of the original image can be found here, which is about 5 'pagedowns' down this page, which has a number of other excellent Huey-model photos. It's a bit of structure to guide the rotor forces into the rest of the airframe, it would not be good if this bit went missing. Fwd/aft, left/right, up/down. The rotor provides the lifting forces and driving ...


3

There are a few things that could be causing it but chances are its not the aircraft. When on the ground, with the engines off, aircraft simply have exterior air circulating through them. In the hot weather they are often connected to an external AC unit similarly in the cold weather they are connected to a heater. Cabin smells tend to vary widely and I cant ...


3

When the aircraft descends for landing, the engines are running at near-idle thrust. So there is not much Bleed Air available to be sent through the packs into the Cabin. So the effect in the Cabin can be similar to "they switched the air-con off".


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