TheRiov wrote:
Vindicarre wrote:
The Riov:
I'm guessing you're not familiar with Saenz v. Roe and Kent v. Dulles, nor the 4th amendment.
Could you provide evidence that the Gov't mandates an altitude of 5-7 miles? FAA Regs. Sec. 91.119 only mandates an altitude of 1000ft. above the highest obstacle within a horizontal radius of 2,000 feet of the aircraft.
They still have to file an FAA Aproved flight plan along specific flight corridors. I'm not a pilot (though I'll check with a few of my friends who are along with my Air Traffic Controller friend (though she's in the UK she may know))
I can shed a little bit of light on the altitudes of aircraft. Granted, I'm a turboprop not an airline jet pilot, and I fly in Northern Canada so the rules are different here than in the US where traffic is much more regulated.
First, today's turbofan engines perform much, much better at higher altitudes than at low altitudes. Their fuel efficiency is much improved up high, and airplanes enjoy a greater True Airspeed at higher altitudes than at low altitudes. True Airspeed is basically the speed at which an airplane is actually flying compared to the air around it; and is a function of the pressure altitude (altitude corrected for the barometric pressure) the aircraft is at with the outside air temperature. The airspeed displayed on an aircraft's instruments is not the actual speed at which is traveling (thats called Indicated Airspeed). I'm not the best at explaining the finer points of airplane dynamics, so maybe a trip to Wikipedia will explain it better haha. As an example, the twin-engined turboprop I used to fly would burn approximately 2500lbs of fuel per hour at 5500feet (slightly over 1 statue mile). If we climbed to 12,500' or 14,500', fuel burns would drop to 2000lbs/h or even slightly lower. Now, this is an older turbine-powered prop engine, but you can still see the advantage. Fuel is very high on any airlines cost structure, if not #1, so you can see why they would want to get the most efficient performance out of their engines. That is just a very basic explanation of the altitude mechanics, you could spend hours reading up on it. For example, look up "coffin corner", which is a pretty neat concept that aircrews have to keep in mind at cruising altitudes.
Another reason to fly up high is weather avoidance. Up at 35,000' there is pretty much no weather to worry about except for the top portions of large thunderstorms, which can be seen and avoided at that altitudes. Turbulence is usually pretty good at those altitudes also, with the exception of clear air turbulence, which I'm sure we've all been the victim of surprise turbulence at cruise level that has spilled our drinks haha. Obstacle clearance is also a non-issue at that height...well unless you're flying around Mount Everest haha. You also have to think about noise pollution from turbofan engines. A airliner cruising around at 1mile at cruise power will likely cause a few barking dogs and complaints from the neighbourhood haha. Up at 30,000', not much of a concern. In Canada we have a speed restriction of 250knots below 10,000' (just under 2 miles) and 200knots below 3000' within 5 miles (around there, can't remember exactly how many) or so of an airport. Obviously airliners can travel much faster than that hehe.
In North America, and I believe Europe but I can't be sure, above 29,000' is what is called Reduced Vertical Seperation Minimum (or RVSM) airspace for aircraft with certain equipment and requirements met. Below that altitude, aircraft need to have 2000' of seperation vertically from other aircraft. For aircraft meeting the equipment standards, and cruising above FL290 (Flight Level 290, aka 29,000'. Above 18,000' altitudes are assigned Flight Levels in 1000' increments), the seperation is reduced to 1000', hence allowing Air Traffic Control to have more aircraft operating safely in the same amount of airspace than before.
Anyways, that's a pretty basic explanation of altitude advantages for aircraft. As I said I'm still relatively inexperienced as a pilot (about 2,500hrs total time) but I still know a little bit about the industry