What response status should write to the Apache2 log if nginx has 499?

Question

Nginx

Initial configuration
nginx 1.10.2, httpd 2.4.6
nginx -> proxy_pass -> httpd -> fcgid -> PHP
cloud service that controls website availability with GET / requests (if there is no response for 10 seconds, this is considered an error, "pinger" closes the connection)
nginx logs
with status 499, httpd with status 500 and script running time of 14-18 seconds
PHP errors are not in any accessible place (application log, PHP log in httpd error log)
everything is fine except for the running time
from this my suspicions outlined in Question
Question
Is it possible that when the connection to the visitor's browser is unexpectedly disconnected, nginx disconnects from httpd so that it logs a 500 error?
Or in other words: if the response is prepared, but nginx is not waiting for it in the httpd log, what is written? the same status 500?
About the unexpected termination of the connection with the browser, I found a lot of tales on the net when searching for status 499 for nginx. "Pingator" is the same browser for the site.