Thursday, August 06, 2009


I just read a post over at The Flying Pinto that reminded me of a past flight experience.

The smaller of Chicago's two major airports is Midway. Here's a view looking down on it.

A number of years ago, on a hot summer day, I boarded a very full plane leaving Midway for the west coast. This was after the heightened security changes which probably made passengers more attentive to announcements and activities before take-off.

As we settled down and waited for the last few passengers, they announced a handful of names and asked that they identify themselves. The requested people responded and shortly thereafter they collected their carry-ons and left the plane.

Why did this happen? The group didn't look related to each other. Nothing noticeably suspicious about the group. Most of the passengers started talking about what happened and asking what was going on.

The pilot came on the PA and tried to explain. I understood but the lady seated next to me was still puzzled. The pilot told us that they had a weight problem and needed to lighten the load some. Granted this is not a common experience, so being puzzled is understandable.

My first thought was "wow I'm lucky they didn't choose by weight because I tipped the scale more than some of those selected passengers".

So then the nice lady turns to me and with a concern tone says,
"Are they going to have enough fuel to make the trip?"

I reply,
"Oh sure, the fuel is not the problem. It's the take-off and NOT having a long enough runway."

The look on her face told me she didn't appreciate the correct answer!

Midway has shorter runways than many major airports. As you can see from the above picture, it's boxed in by the city streets and buildings. Only narrowbody planes like Boeing 737's can use the airport.

If you think about it, the weight increases the required power to get upto take-off speed. A longer runway gets you more time to reach that speed. Also, (I don't know the details) the temperature of the air has a negative effect. Hotter makes take-off harder.

The rest of the flight was uneventful.

Do you often wonder or ask WHY?

I think you should because that's important to learning more about the universe around us. You never stop learning.

A favorite scientist of mine, Richard P. Feynman wrote a book of short works titled, "The Pleasure of Finding Things Out".

He wrote:
" You investigate for curiosity, because it is unknown, not because you know the answer."



The Flying Pinto said...

Great post! I think your right most people just "accept" what is going on around them. It is good to keep learning! It keeps your mind young too: )

Bill Lisleman said...

@flying pinto - wow that was a quick turn around for getting you to visit. You must not be flying with cabin Wi-Fi right now. Of course checking your blog while on duty might be another problem all together.


Anonymous said...

Yep hotter means molecules are moving faster making the air less dense.

So on a given hot day, the engines are sucking less air producing lower thrust compared to a cooler day.

The aviation speak is "Density Altitude." You can read up on it here:


yorksnbeans said...

Sometimes I ask why too much! :-)

Bill Lisleman said...

@anonymous jay - thanks - Density Altitude - I'll try to remember that next time I fly and ask the pilot on the way out.

@yorksnbeans - no such thing as a dumb question - there are dumb answers though. Keep asking and wondering why.

Lisa said...

Neat picture, looks like a computer chip.

The folks that got off the airplane, they were well compensated I believe.

Bill Lisleman said...

@ocean girl - the pic is from some government survey agency. The removed passengers probably got a free ticket. I still wonder how the airlines made the selection.

how to become a beautician said...

i do!!!
i mean, i always ask WHY
whenever my curiosity tickles
my own playful mind..

and when i start asking WHY,
i can't sleep or stay put
until i know WHY..

Lisa said...

Hi lisleman, thank you for your help. I know it is confusing because the display is the outcome and not the how to. I will work on it and refer to the help page you suggested and also get help from my son (he probably knows how, not sure). Thank you.

Lilly said...

You always have interesting posts you know. I would have freaked out really. Surely they must have realised that before they booked people on the plane dont you think? I would ask then wouldnt beleive their answer and would ahve prayed all the way to my destination.

Bill Lisleman said...

@lilly - I get some of it from reading interesting blogs like yours and others. The airline would not have known much in advance because it depends on the current temperature and if everyone shows up. But they could of figured it out before everyone got aboard.

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