When spotting a flying 737 from the ground. How do you tell the difference from a -300 and a -500?
Thanks!

at first i thought you were asking what the difference was between them. That would be a stupid question.

I think one is longer. but you cant really tell between long and short from the ground.

different altitudes give you different illusions

low 737-300 may appear as a 737-500 to the untrained eye and viseversa

Then again i dont know anyone who can tell

You might learn which airline has 735, and which has 733. If one airline has both, you´ll have to get a feeling how short the 735 really is.
Daniel 

Lufthansa operate both into Heathrow which can be confusing but you only have to see the 2 letters on the tail to work out what type it is.Alex

When looking at them from sides, it's EZ (length, registration,...), but when looking to one, flying directly over you, it's definitely harder to tell. As a matter of fact, I'm not 100% able to tell whether it's a -300,-400 or -500, just by looking to a 737 flying over my head.

Ivan

Here is a couple side shots........

Click for large version

Photo © James Richard Covington, Jr

737-322 Standard legnth


Click for large version

Photo © James Richard Covington, Jr

737-522 Shorter-body

BTW 737-400 is longer than a 200/300 Series.

talking about the Lufthansa 737s... You can tell it very easy since on the 735 the name "Lufthansa" ends over the wing while on the 733 the titles end in front of the wing... Btw: the -400 is easy to tell because it has two exits over the wing. ...Well that could then also be an -800 or a -900...  

Generally, I look to the size of the forward set of windows ahead of the air conditioning duct. See for yourself.

Click for large version

Photo © Joe Fernandez - Aviation Photography of Miami

737-300 series


Click for large version

Photo © James Richard Covington, Jr

737-500 series

Notice there are about 1/2 as many windows on the -500. If you are looking at the aircraft at a perpendicular angle, you will also notice more windows aft of the wing, but it is much more defined in a comparative view with a -300. It is easiest, however, to just look at the forward set of windows ahead of the duct. If they look unusually small in number, then it's a -500. I believe the ratio is 12/6 for windows (as -300/-500) for the section forward of the a/c duct. That is a structural property and will not vary from customer to customer unless the windows have been plugged or it is a dedicated freighter. Therefore, if it is a passenger plane, the amount of windows is a sure bet to tell you which is which.

Never could tell between 3&500. But the 400 has 2 emergency exit windows over the wing, whereas the 300 and 500 only has one like the 200.

Im going to ask the stupid question, but what is the diff between the 300 and 500:?