Stop Margin is based on OAT / FLEX Temp?
I was flying on an ordinary day and calculated the TO Data, using LPC Software provided by my company.
The stop margin calculated was 29 meters with the flex temp of 60.
I advised my captain if he wanted to take off with a lower flex temp of 59, as to achieve higher stop margin.
He refused, and without me knowing his reason I inserted the TO Data with the Flex temp of 60 in the FMGC.
A few mins into cruising he brought up why he doesn't want to take off with lower flex. I understand one of the reason was for engine life in the long term and I couldn't agree more with him.
But his statements that is still stuck in my head is about the stop margin...
He said the stop margin WILL ONLY be 29m ONLY IF the OUTSIDE AIR TEMPERATURE is 60 Degrees Celcius (As the FLEX TEMP is 60 Degrees). Of course I did not argue with him, but I kinda disagreed with him on that.
So from his explanation, this is his point of view....
What he's saying is the stop margin result of 29M will only be achieved IF the ACTUAL OUTSIDE AIR TEMPERATURE is MATCHED WITH the FLEX TEMP.
OAT at that time was 30 Celcius
I'm not sure if he's correct. However, this is my simple explanation of stop margin, correct me if I'm wrong...
The Stop margin (in my case, it was 29M) is the remaining distance of when the takeoff is rejected at the speed of V1 until it comes to a full stop before it reaches the end of the runway. Again, that is the simplest form of explanation that I can come up with.
Therefore, it brings me to the conclusion that the OUTSIDE AIR TEMPERATURE DOES NOT HAVE TO BE THE SAME AS THE FLEX TEMP, in order to achieve that STOP MARGIN.
While as my captain thinks that the result of the stop margin computed, is based on THE OUTSIDE AIR TEMPERATURE HAVE TO BE THE SAME AS THE FLEX TEMP that we insert on our FMGC.
I'm a new first officer and I'm still learning as I'm pretty sure most of you guys do here, so please enlighten me on which conclusion is right...