OK, don't laugh at this question. I should know this by now.I've noticed on sectional charts some numbers--a large number always followed by a smaller one. I've looked at online resources on sectionals and looked at the sectional legends, but still I am uncertain what these numbers mean. I have attached an example with the numbers circled in red:-John

Tallest obstruction or terrain altitudes (above sea level)...Big number = thousands,Little number = hundreds51 = 5,10073 = 7,300Fly above those altitudes in those particular grid squares and you're guaranteed not to hit anything that isn't already flying. :) -Greg

>OK, don't laugh at this question. I should know this by>now.>>I've noticed on sectional charts some numbers--a large number>always followed by a smaller one. I've looked at online>resources on sectionals and looked at the sectional legends,>but still I am uncertain what these numbers mean. I have>attached an example with the numbers circled in red:they are called MEF's (Maximum Elevation Figures).check out page 2 item #5.http://flighttraining.aopa.org/members/stu...art_Symbols.pdf

Thanks guys... I deleted the image I included given your answers since I didn't want a scanned sectional holding Avsim accountable for any copyright issues...-John

You can download the NACO Aeronautical Chart User's guide in .pdf format from the FAA NACO Web site: http://www.naco.faa.gov/index.asp?xml=naco/online/aero_guideThe guide explains all the symbols and terminology used on VFR and IFR charts published by FAA NACO.