Small Aircraft
Flight Crew Private
Other / Unknown; Communication Breakdown
Conflict NMAC
Flight Crew Took Evasive Action
Airport; Human Factors
Winds Light and variable; AMW runway 01 specified for no wind use. After runup; announced on CTAF taking runway [01] for departure. Another person on CTAF said they were lined up on runway 13 [which is closest to the ramp] -- said they wanted immediate departure. I said I would stay lined up on 01 and they could depart. I watched; lined up on 01; as the plane took off and watched it climb to about 500' and they announced turning crosswind to stay in the pattern. I said; I was rolling on 01. At about 10' AGL someone [unknown] said there are two planes taking off! I started looking toward runway 13/31 and couldn't see; my passenger pointed and the vintage aircraft was rapidly approaching the intersection of 13/31 [on Runway 13] and 01/19 at the same altitude as me. He was less than 100' away horizontally as I immediately pitched down (about 50' AGL at this time) and he flew over the top of me. I had to recover and pitch back up about 10' AGL and continue takeoff as I was hitting 100 kts and was not stabilized nor had enough runway to land on back on 01.I can only assume the pilot was NORDO or just not listening and assumed there was only 1 active runway. I listened and heard no reports on the radio from that plane.Factors in play were the NORDO pilot; or not using CTAF if he was equipped. The fact that some pilots use the closest runway in no-wind conditions when 01 is spelled out as the no-wind desired runway. Also beneficial was the one pilot who saw both planes departing and called out on the radio -- if this hadn't happened I don't know if I would have avoided the other plane. Also a factor is you can't really see the departure [approach?] end of 13 from 01 and vice-versa.
The reporter confirmed that the vintage aircraft was departing from Runway 13.
GA pilot departing using CTAF procedures reported a NMAC with a vintage aircraft departing on an adjacent runway without announcing on CTAF.