Tuesday, June 25, 2013


I'm at an airport. I've been here before. Some of you have too, no doubt, and will recognize it from the following I know the essential things a transient pilot needs to know. I know the gate code to return to airside. It's a truncation of a famous mathematical constant. I know how to find the fueller. He often monitors the traffic frequency so if I announce my need for fuel exiting the runway, he'll probably park the fuel truck in front of the airplane as I shut down, but if that doesn't work, there's no specific FBO frequency. He has an office with an entrance inside the airline office, so I can ask the customer service agents at the airline counter to alert him for me. I know where the women's washroom is. It's downstairs past the stuffed bear. The men's is probably there too, but a sign implies there's a unisex accessible washroom on the main floor, for those who can't navigate stairs. I've filled my water bottle in the women's washroom before, but the water from there tastes terrible. Much better-tasting water, and baked snacks are available at the café.

On this particular occasion all my knowledge of this airport does not help us have a quicker turn because we are waiting here for something. I don't remember what we're waiting for. It' snot my job to decide when it's time to leave. It's my job to be ready to leave when I'm told it's time to leave, or to explain succinctly why we can't. On this occasion I am waiting in the café for whatever configuration of factors is required for it to be time to leave. I have eaten all the baked snacks that I require and am now entertaining myself by reading a book that someone has left at the café. I don't have a really discriminating taste in literature. I'm reading Maximum Boy starring in Attack of the Soggy Underwater People by Dan Greenburg. Its eleven year old male protagonist obtains superpowers from moon rocks. He also has to get his homework done. The story climax is predicated on an immediate need for ammonia at the north pole. Mr. Greenburg nursed my willing suspension of disbelief all the way through the scenes of conflict with the protagonist's sister, negotiations with the titular soggy underwear people and meetings with the president and then broke the whole concept by having Maximum Boy identify the the helicopter pilots (they were also at the north pole, but I won't spoil the whole story) as a potential source of ammonia. They use Windex to clean their helicopter windshields. Noooooo! It spoiled the story for me. It wasn't a detail. It was the pivotal moment in the story, and it was supposed to be a science teaching moment too. There's no way the helicopter pilots were using ammonia-based Windex to clean their acrylic windshields.

If you're cavalier with the integrity of your windshield you might use non-aviation specific products like Pledge furniture polish or acrylic polish marketed for the marine industry, but generally pilots use a product specifically designed and marketed for care of aviation windshields. The windshield allows us to see oncoming aircraft; it keeps the air inside pressurized cockpits and it protects us from the onrush of air and particulate matter we're flying through. If it fails in any one of these endeavours we could die of the results. Windshields and their care are kind of a big deal. I've heard and generally abide by the vertical strokes only rule too. The idea is that if you put a scratch in the window you definitely don't want it to be in a direction that would align with the wings of an oncoming aircraft.

I usually use 210 Polish, but if I run out and I'm in Winnipeg or something, I may have to settle for Prist (not to be confused with the fuel additive). Prist is foamier and doesn't work if you keep it in a cargo compartment where its temperature drops below freezing. And neither of them contains Windex. And that is why I am never supporting the Maximum Boy franchise again. I didn't think much of the new Star Trek either.


Anonymous said...

Never seen anybody use Coke to clean a windshield? They are real glass in the big jets, which is pretty much impervious to anything.

Also the newer Windex variants don't contain ammonia anymore, probably due to the spread of plastic windows. Only "Windex Original" is guaranteed to have ammonia.

Anonymous said...

You don't say why you would not use Windex (with ammonia) on your windscreen. I have just used Sensodyne toothpaste on my car windscreen to try to remove something embedded in it that causes it to blur in rain or cold temperatures. Acetone, thinners, carb soda, detergent etc. did not work. The pre-wash spray in car spray booths seems to etch glass and aluminium so I suspect that it has ammonia in it.

A Squared said...

Anonymous said: "The pre-wash spray in car spray booths seems to etch glass and aluminium so I suspect that it has ammonia in it."

About the only chemical I can think of which will etch glass is nitric acid, and I doubt that car washes are using that. For certain, Ammonia does not etch glass, that's why you'll find it in glass cleaner.

Curious Chemeng said...

Ammonia will turn acrylic opaque and unusable as a window.

As far as glass goes, there's a reason lab equipment is mostly glass - it'll resist nearly anything. HF (hydrofluoric acid) is a glass etchant and works very quickly. It'll also ruin pH probes, because those don't work very well when their glass sensing tip is etched.

Aviatrix said...

Thank you Chemeng. I was so consumed with the horror of Windex on an acrylic windscreen that I forgot to say why.

LocalFlightEast said...

The use of a "truncated mathematical constant" as a code must be a pilot thing.

Our airside gate is the same but I don't think we are talking about the same place. I would have noticed the bear I'm sure

Lukes2k said...

We used Windex to clean our helicopter windshields in the Army all the time. That being said, ours are made from glass. Not all helicopter windshields are acrylic.

Anonymous said...

A Squared: alkaline solutions will etch glass, and I just looked up what they use for presoaks, and they are specifically made to be alkaline. They even make acidic presoaks which contain HF (Presoak X by Chemquest), probably exactly to etch glass.

Aviatrix said...

Lukes2k, you saved the book! Huzzah!

majroj said...

Having washed or polished acres of VEHICLE (glass) windshields and faceshields (polycarbonate or acrylic) in the aviation firefighting business, the following:
1. Ultraviolet from the sun (especially at altitude) attacks some plastics such as are found in some safety glasses and so-called "bulletproof" laminated glasses. A UV shield is usually on the intended exterior side, and it can sometimes be subject to wear or chemical attack.
2. Abrasives (blowing sand, scouring powders, dust, high-speed bird strikes, dirty washstand tools /chamois/water) will definitely and rapidly cause damage to glass or plastic.
3. Abraded windscreens scatter light at night like a disco ball, or worse.


Traveller said...

I get annoyed by similar things when I am reading. I don't mind if the background star field is not correct in a movie, but I have little tolerance for basic, obvious errors. An otherwise good story in the Star Trek universe was ruined for me by the author having Chekov and Sulu swapped as to their jobs. Everything else was perfect.

BTW, my opinion of Abrams and the new Star Trek are not for polite company.