As a retired firefighter I have to submit that allot of factors are involved in response time. Suppose the closest unit was on a call, so the second closest units( and a plane crash would call for multiple units) responded. From time of crash to time of on scene time could easily be 20 minutes.
It takes time for people to call 911 and answer questions, then dispatch units, then they run to the truck and start it and start the drive. Then traffic, including trains and other wrecks can influence the time.
Plus... a plane often crashes out of town..... so there is the time trying to find the incident. Just FYI
Some of those factors surely affected firefighters arrival time. Its just a good reminder for us to always be ready to fend for ourselves in the first critical minutes.