Hot answers tagged

52

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 dew, and more generally to fog (which is dew over the ground) which appears when humid air is close to a cooler ground. Dew and fog appear when air temperature is lowered below its dew point (see further ...


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 ...


23

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.


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 ...


11

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 cruise. In a ...


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 ...


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 ...


7

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 ...


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 (...


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

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 ...


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 ...


5

"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 ...


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

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. ...


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".


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

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 ...


3

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) ...


3

How do manufacturers select the cabin pressure? In principle, the optimal cabin pressure for people on board of an aircraft would be sea level pressure. However, this would create very large pressure differentials between the inside of the aircraft and the outside at high altitudes, which puts a lot of stress on the fuselage. One could build an aircraft ...


3

Yes you simply fly with the pressurization system set to a mode that holds the outflow valve open so the air conditioning air being pumped in can't "inflate" the cabin; it all just goes overboard. Most transport aircraft have a specific QRH procedure for "unpressurized flight", which among other things, limits the maximum altitude to 10000 ft, the altitude ...


2

This is a very difficult question to answer, but lets assume that you're flying during cruise, eliminating as much airframe noise as possible (landing gear, flaps, slats and spoilers) then the position of you in the aircraft is of importance as well. The further you go to the front the more silent your flight will be. Since the A380 also has an upper deck ...


2

If the engines are off, ie. durring boarding or while waiting at the gate, the APU can supply the necessary bleed air and electricity to operate the PACKs that supply air conditioning to the cabin. It is up to the crew to decide wether to use it or not, depending on ambient conditions: on a nice 21deg sunny day vs. a cold and snowing -4 deg. Now that APU ...


2

The aircraft when on ground and starts to board passengers is switched to ground power or auxiliary power which runs the air conditioning system. When disconnected, the engines supplies the power and bleed air for the cabin pressurization. "On the ground, the airplane is unpressurized and the outflow valve is wide open. During preflight, the pilot sets the ...


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