Passenger jets

[Pootle]

Why do passenger aircraft fly at such high altitudes? Is is a noise issue, more economical or smoother ride? Thanks in advance

[Loosehead]

higher = less air = less resistance = less fuel = less dosh!

[MargeB]

It used to be for that reason, Loosehead, but modern aircraft design are not so much constrained by such issues as to make getting up to that height economical.

Pootle, it's mostly for safety. In the event of catastrophic engine failure, even a large aircraft can be safely glided down from 35,000-38,000 ft and safely landed. Until recently I trained and flew for Pudniw Airlines in Indonesia, and you cover this on Day 1 of training.

[Mattk]

is that right ? you can glide a plane weighing several hundred tonnes to earth ?

someone said this at work last week but i didnt believe them.

[MargeB]

Its absolutely correct. The wings are designed with extra lift capacity at the expense of overall speed/efficiency. Even a 777 will go for several hundred miles with no engines. We were trained to do this at the Lupgel in Germany, the European Aeronautics training centre.

[Tim Baxter]

Given the height I would imagine that a brick with cob-webs for wings could go for several hundred miles!  But.... what happens then?  What is the terminal speed having 'glided' for that distance.  I note that the Shuttle has to land almost upright to kill its speed before landing 'softly'.

Interestingly, to digress a little, did anyone see the bloke who body surfed (well, with bat wings) through the air over the channel recently?  Amazing!

[MargeB]

Still can't quite believe what I saw there, Tim. Batman? I'll give you BATMAN!