Yeh, I'm surprised by the lack of panic or even nervousness among the pax. If I were a PAX I certainly wouldn't be comfortable if I saw that at first...

 

Regards,

Ró.

Sure, I actually meant having packs off being mandatory would save engine life, no idea why pack to apu was never used.

 

Decided to check if anyone had made a recording on youtube. Found a video from the USA, the effect in the vid is nowhere near as bad compared to operating in extreme temps and humidity but it gives you an idea of the amount of mist pouring out of the vents.

 

 

Actually this is a much better example

 

http://www.youtube.com/watch?v=TpKcv3hv5U0

 

I actually saw mist pouring out of the vents exactly like in the first video while boarding a Jetstar A320 in Cairns. Was surprised and didn't know what to think, certainly didn't look like something that was "supposed" to be happening inside an aircraft :biggrin: But the captain announced over the PA that it is caused by the high humidity outside. Certainly quelled my nervous flyer mum's nerves as I'm sure many other passengers!

Any particular reason you push a large jet into a 6500 fpm climb rate????? Just curious!

 

They aren't pushed. It is their natural rate of climb. The 767, when not loaded up with fuel, has one of the best power to weight ratios out of PAX jets in the world.

 

I actually saw mist pouring out of the vents exactly like in the first video while boarding a Jetstar A320 in Cairns. Was surprised and didn't know what to think, certainly didn't look like something that was "supposed" to be happening inside an aircraft :biggrin: But the captain announced over the PA that it is caused by the high humidity outside. Certainly quelled my nervous flyer mum's nerves as I'm sure many other passengers!

 

Yes. I had it at BKK the other day. But I think the Thai A330-300 had a humidifier on board, as the air wasn't dry. The only carriers I knew which had them was British Airways, on their 747-400s.

I know Cathay Pacific don't have them, as the air gets pretty dry up their at night.

As far as I know BA only use humidifiers during the cruise. i.e. one hour after take-off and one hour before descent.

An interesting article on Humidity during flight.

 

http://www.flightglobal.com/news/articles/in-focus-manufacturers-aim-for-more-comfortable-cabin-climate-369425/

Also keep in mind that most climb profiles are based on using the most efficient climb speed and max climb power. When light, you will have a higher rates. Pressurization can become a factor in some aircraft. the systems are designed to give you about a 500ft per minute cabin climb schedule(comfort). Climb too fast and the system will will go off schedule. During the differential pressure phase, there is a chance that you may out climb the cabin causing the diff pressure to increase too fast. When i flew dc-10s, this would cause the 3 over pressurization valves to trip causing a load thump. The cabin climb would increase quickly and you would feel it. Not too bad of a thing, but it gets your attention causing none crew members to show concern. The Mx guys would give you a hard time because they would have to reset the 3 indicator tabs exposed on the outside of the aircraft. Another factor is passenger comfort. In my ops(G5/550), we use 2000 to 2500 vert speed if there are no obstacles based climb gradients. This keeps the deck angle at a comfortable level. When dealing with high climb gradients, I brief the principal about the climb profile. Personaly i'd rather use FLCH, but it's not my call. FLCH can get pitchy passing through temperature layers and when climbing in mach mode after mach change over. When flying without a VIP, i use FLCH all the time. Ive seen rates from 4000 to 6500 at 13,000. Big thing is to increase vert speed until the engines are at max climb and then select FLCH. The plane should'nt pitch at all when done right.

 

Lastly descents are another story. At high altitudes when descending from cruise, most descent profiles keep you on a economical path normally about a 2.5 descent path. More like a enroute descent. This keeps you up longer to minimize fuel burn at the lower altitudes. Even when ATC requests/gives me a min rate, I keep it to the minimum unless he has kept me up too long. I then bug them constantly. This situation does lead to higher descent rates. At high rates, speed becomes a issue. This leads to speed brakes, after all thats what they are there for..but it goes back to passenger comfort. At lower altitudes, 1500 fpm is the max you can get clean and maintain 250kts. This has been true in all of the jets i've flown. I use the 12 at 12 technique. Passing 12,000, i set 1200fpm and the jet will usually reach 250kts as i pass 10,000. Below 10,000 with slats or flaps(gufstreams) i've noticed that the max you see is about 2000fpm without speeding up and over speeding something. Big thing is getting slow enough to dirty up. Of course, you can fully configure and get more descent rates. I've had to do that when flying steep approaches or when slam dunked by ATC. As long as you are sure you can get the glide path by 1 mile, should be fine or just request the dreaded 360. S turns help but raises passenger concern.

 

Just my experiance of course.

Rich