posted 07-19-2003 08:04 PM            

Yep, I'm absolutely sure that we'll get the same story from the debunker crowd that we've been getting for years.

This is something the crowd in the basement Rumpus Room can cut and paste...and giggle over.

"Perfectly Normal".

Heh Bart, what was that you said?

Oh, "You didn't see me do it, you can't prove a thing!"

posted 07-20-2003 12:35 AM            

Sorry about the topic spelling.

I've been having a lot of eye irritation recently...inflamed eye lids.

Local optometrist says she's been seeing a lot of people come in with this condition.

By the way, from my point of view, it appeared that there's been a major increase in artifical cloud cover recently.

SF Bay Area.

But then, that's just my opinion...and I'm strictly an amateur at this.

Not the trained "professional" that can instantly look at the above photo and say that it's just a "normal" holding pattern.

posted 07-20-2003 12:35 PM            

I interpret the following explanation to mean that Air Traffic Control places commercial airliners into pre-landing holding patterns at an altitude of 24,000 feet or lower:

How Air Traffic Control Works www.aviationboom.com/ATC/atc_works.shtml

Excerpt:

En Route and Descent

Once your plane has left TRACON airspace, it enters a sector of the ARTCC airspace, where it is monitored by at least two air traffic controllers. The radar associate controller receives the flight-plan information anywhere from five to 30 minutes prior to your plane entering that sector. The associate controller works with the radar controller in charge of that sector. The radar controller is in charge of all air-to-ground communication, maintains safe separation of aircraft within the sector and coordinates activities with other sectors and/or centers.

The controllers must monitor the airspace at **high altitude (above 24,000 ft/7320 m)** and **low altitude (below 24,000 ft).**

The center controllers provide your pilot with updated weather and air-traffic information. They also give directions to your pilot regarding such aspects as speed and altitude to maintain a safe separation between aircraft within their sector. They monitor your plane until it leaves their sector. Then they pass it off to another sector's controller.

Another controller, called the radar hand-off controller, assists the radar and associate radar controllers during times of heavy traffic, watching the radar screen and helping to maintain smooth air-traffic flow. While you are enjoying your meal, snack, in-flight movie or the view outside the window, your plane gets passed from sector to sector and center to center. In each sector, center controllers radio instructions to the pilots. The path of your plane may have to be changed from the original flight plan to move around bad weather or avoid a congested sector. Your pilots may request a change in altitude to avoid or reduce turbulence. This back and forth between pilots and center controllers continues until you are about 150 miles (241 km) from San Francisco (your destination).

At this point, the center controller directs all planes flying into San Francisco to move **from high altitudes to low altitudes** and merges the descending aircraft into a single file line toward the airport.

The controller gives instructions to your pilot, such as changes in heading, speed and altitude, to place your plane in line with these other aircraft. Depending on traffic conditions, the controller may have to place your plane into a holding pattern, which is a standard route around each airport, where you wait until the airport can handle your arrival. The controller continues to give directions to your pilot until your plane is within TRACON airspace. END excerpt.

Comment:

Normal contrails, we are repeatedly told, cannot form below an altitude of 25,000 feet because it's not cold enough below 25,000 feet for the contrail formation process to take place.

Commercial airliners, according to the above-referenced explanation, are placed by ATC into pre-landing holding patterns at what is considered "low altitude" - i.e. at 24,000 feet and lower.