Thursday, May 31, 2007

Aerosol in Contrails?

I hate to even give these guys a forum, but you can find a link to their conspiracy-minded lunatic ravings here. In short, they believe that the government has a secret program to poison or control the populace through aerosol dispersal of chemicals via airplane. They use photos like those found on this website as their "evidence."

Let me say unequivocally that there is no such program! Contrails are a natural phenomenon that occur when air at the right temperature and moisture content is passed through a jet engine. The advent of high-bypass turbojets (what you see on virtually all airliners these days) makes them even bigger. Within the contrails are signs they were produced by a large machine. This guy believes there are "cores" in the contrails. Those are caused by the engines themselves. High-bypass turbofans have two stages...the large fan stage that provides the vast majority of the thrust, and the smaller, but much hotter, core stage that provides the power to spin the fan stage. Both turn on the same axis with the N2 stage being interior to the N1 stage. With the right atmospheric conditions, the N2 stage (the smaller one) can create these secondary trails within the primary. There can also be a pattern of disruption from the wake turbulence from the wingtips. How they behave after creation has to do mostly with upper wind action. Every one of the pictures this guy shows can be explained. One thing's for sure...they really are neat pictures! But his conclusions are that of someone needing to wear an aluminum hat to protect himself from the aliens!

The specifics of any particular contrail has to do with the condition of the atmosphere in which the plane is flying. Thus this guy's "control photographs" are nothing more than a plane in different atmospheric conditions. I do know from time spent in NM that the skies there are often fabulously blue. There are also a multitude of jet airways that overlay the state. As a result, there are many days when the contrails are numerous and happen to stay around a while. There are other days when I fly when there are no contrails present. It's up to the atmosphere. Period. The altitudes at which you can expect contrails can actually be predicted. The military does this because a fighter certainly doesn't want a large white trail pointing the enemy to his plane! When in enemy territory, they will avoid the contrail altitudes in order to avoid easy detection.

And on top of that...we as pilots know our planes inside and out. This is necessary in order to deal with any malfunctions that occur. If there were actually something on our planes that would distribute this material into the air, we would know about it so we could deal with it in the event it malfunctioned. That would mean that there are tens of thousands of pilots who are all keeping their mouths shut. Oh...and then this device would have to be serviced, both in terms of regular maintenance and in terms of loading it with whatever this "chemical" is supposed to be. That would mean thousands upon thousands more people involved. It's getting really, really hard to keep a lid on such a "secret" program with that many people involved!

Sorry...enjoy the contrails in NM...but you have nothing to worry about but fluffy white water vapor!

Thursday, March 22, 2007

A Bad Day at JFK Ground Control....

Here is a link to a website that has a recording of a period of time at New York's JFK airport ground control. It's obviously a zoo, and the controller is barely keeping things straight. Remember this the next time you think your job is stressful!

Sunday, February 11, 2007

Avoiding Midairs

I had a commenter ask how we in the airline world avoid midair collisions. Given the number of planes in the air at any given time, that is certainly a valid question...and a valid concern! Obviously the result of one would ruin the day of a lot of people.

Except for a few remote places, airliners always operate under IFR (Instrument Flight Rules) and are under the direct observation and control of ATC (Air Traffic Control). They have very, very strict separation criteria and there are stiff penalties to be had for the controller should he allow that separation to be lost. We also fly at altitudes appropriate for our direction of flight. Eastbound flights are at odd altitudes; Westbound flights at even altitudes.

And when all else fails, airliners are equipped with Traffic Collision Avoidance Systems (TCAS). TCAS puts a protective "bubble of time" around the plane and monitors all other nearby traffic, predicting whether or not they will enter that bubble. If it appears they will, it alerts us to the traffic. If it becomes more probable, it actually commands a climb or a descent in order to avoid a collision. But even cooler is that if the offending aircraft is also TCAS equipped, my TCAS will coordinate with the TCAS on the offending plane so that both aircraft maneuver away from each other. These maneuvers are not abrupt; TCAS has undoubtedly already saved countless lives...and the passengers never even knew it!

Saturday, January 06, 2007


Depending on where you are flying, deicing can be a routine event. The FAA requires that planes not attempt to takeoff with anything adhering to the upper sides of the wings and tail (there is a minor exception for the underside of the wing) because it can significantly effect the ability of the wing to generate lift. The way this is accomplished is through the application of deicing fluid prior to departure.

Many larger airports in climates where deicing is a major event have setups where the plane taxis to a pad near the departure runway and is deiced with its engines running. That way, there is minimal time between the deicing and the takeoff. These pads are also usually designed to recover excess deicing fluid both for reuse (after reprocessing) and to prevent it from entering the surrounding environment through runoff.

Anything on the wing is initially taken off through the application of what is known as "Type I" fluid. This is a heated glycol/water mixture that is very effective at removing any contaminants from the wing. Unfortunately, though, it doesn't do much when it comes to further accumulation.

Enter "Type II" and "Type IV" fluids. Now these are very cool! Their viscosity is directly proportional to the speed of the air passing over them! This means that at slow wind speeds, this fluid is "sludgy" and sits on the wing. Any snow or ice accumulates on top of the fluid. At about 60 knots of speed during the takeoff roll, this "sludge" becomes "liquid" and shears off the wing, taking any accumulated ice and snow with it. This allows for much safer operations when there is significant snowfall.

So now you know a little more about what they are doing during the next blizzard in Denver!