your contrails are probably connected to the light system but without guage control or they might be on the smokesystem
just try hitting the i key see if they turn off.. same with the lights
if so you need to configure a guage in the panel cfg..

at the end of the (VCockpit **) you need to add one of these
but with your contrail effect...you'll notice from this that i'm using the t38 wingtip effect for this perticular plane which is the a10 by the way....
[VCockpit15]
size_mm=512, 512
pixel_size=512,512
texture=$h_cluster
background_color=0,0,0
visible=0
gauge00=T38COF_FX!T38_WingtipSTROBE74R4, 3,3,1,1
gauge01=T38COF_FX!T38_FlaptipRECOG18, 2,2,1,1
gauge02=nn-gauges!NickSmokeFXControl2a.xml, 0,0