Hi to all,some days ago I've read a topic in this forum that now I can't succed to find where a "colleague" have doubts about the correct flight dynamics of PMDG 737 vs. the real bird regarding accelerarion during takeoff run and then about takeoff length itself and for this "based on personal sensations" he decided to modify the engine part of the AIR file....Apart that modyfing the air file based on "personal sensation based on a real flight as passenger" without having precise data to compare semms to me a nonsense I wanted to make an (ampiric) test:I started by using TOPCAT calculator and considering a very demanding situation: a takeoff from Firenze Peretola rwy 05 (LIRQ). LIRQ it's a very demanding airport, also in real life, with a short (1750meters/5950 feet) rwy and the bigger planes operating there are the A319s of Meridiana company. Others considerations are based on the fact that there are hills near the airport etc. (but I've not considered that).I used the meteo conditions existing two days ago: wind 040/05 qnh 1012 temp 35

hi Andrea1,

The first: a normal 2 engine takeoff: Seeing at the replay the plane began rotation at about 133-134 ktos and lifted off 3 second later at about 8-10 degrees of attitude and I had about 2-2,5 seconds before overflying the runway edge (let's say 150 meters that it's the margin worked out by TOPCAT) but the heigth I obtained was about 18-20 ft AGL not satisfactory considering that FAA and others Int.autorithies require 35' minimum.

FAA/FAR req says: 35' about the end of the TODA. Thats must not be the end of the runway.TODA= useable runway lenght + clearwayclearway: max. 50% of TORA (useable rwy lenght)Requirements for clearway: 75m to the right and left of extended rwy-centerline, max. 50% of TORA and a climb gradient of 1,25% starts at the end of the rwy.Trough this area no objects(exeeding 0.9m) may protrude.For LIRQ, you are climb/rwy limited, due to missing clearway and obstacles in vincinity of aerodrome. You could use for testing YBHM / Hamilton I. - Australia. There you have the best testing conditions^^Hope that help`sMfG